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Trash or Recycling? Why Plastic Keeps Us Guessing. - The New York Times

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Trash or Recycling? Why Plastic Keeps Us Guessing. - The New York Times

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Hiroko Tabuchi and Winston Choi-SchagrinApril 21, 2022

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Trash or Recycling? Why Plastic Keeps Us Guessing.

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Did you know the “recycling” symbol doesn’t mean something is actually recyclable? Play our trashy garbage-sorting game, then read about why this is so tricky.

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The Circular Classroom: a Free Toolkit for Activating the Circular Economy through Experiential Learning | by Leyla Acaroglu | Disruptive Design | Medium

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The Circular Classroom: a Free Toolkit for Activating the Circular Economy through Experiential Learning | by Leyla Acaroglu | Disruptive Design | Medium

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Finland is, by many accounts, known as having the world's best education system, thanks to its no-homework, student-centric, interdisciplinary, life-skills teaching approach, and for its commitment to experiential and phenomena- based learning (more on this here, here and here).

So when I was invited last year to work on a progressive initiative to design curriculum focusing on the Circular Economy, sustainability, and creative problem solving for Finnish high schools, I was extremely excited by the potential for this project to have far-reaching educational impacts.

The Circular Classroom is a free, multilingual educational resource for students and teachers alike, designed to integrate circular thinking into high school and upper secondary classrooms in Finland, all packaged up in a fun, beautiful format. It offers the opportunity to think differently about how we design products, how the economy works, how we meet our needs as humans, and how to support the development of more creative professional roles that help to design a future that is about social, economic, and environmental benefits.

In this article, I have summarized the project development and outcomes, including an overview of the content, the design methods employed, and the framing of the curriculum through experiential education. We have to give thanks to Co-founders Ltd who initiated this, invited me, and managed the project, and to the Walki Group, who graciously funded its development and was happy to respond to my demand of keeping it as a free resource. It is always so great to see private-sector investment in progressive education, especially when it's about designing for a better future!

Introduction to the Circular Classroom

Designing for Change

The intention behind this entire project is to support young people in recognizing the exciting opportunity that redesigning products, services, and systems have for the future; for exploring how their engagement with the world today impacts the future; and for supporting their decisions around future professions. It's about making sure that they have the tools and agency to overcome the pessimistic worldview so often painted when global planetary issues are discussed. Furthermore, the resources support educators upskilling in this new and exciting (but immensely complex) arena of circular and sustainable activities.

I designed the Circular Classroom curriculum materials through a co-creation process utilizing the Disruptive Design Method. The outcome of this process (described in more detail below) includes three main knowledge-building modules, with each consisting of a short introductory YouTube-style video to establish core concepts, an extensive workbook filled with knowledge-building content, and activities for collaborative, experiential, real-world learning in the classroom.

Working with the very talented illustrator and designer, Emma Segal, we took great effort to create a visually beautiful and highly engaging design aesthetic and communication language for this project that would speak to the students. Her illustrations were designed to translate complex concepts into accessible and approachable visuals that help to reinforce and integrate the activities. Each of the 20+ in-class activities were created as an emergent outcome of engaging directly with students and teachers through a series of co-design workshops held in Finland.

Additional to the three main in-class modules, we created a valuable Teachers' Support Pack that includes details on how to integrate the content into the classroom, prompts for employing experiential learning activities into lesson planning (with a connection to the Finnish curriculum), and ideas for more complex conversations around circularity and sustainability.

The outcomes of the co-design workshops included a focus on activating both educators and students, as well as supporting the participants' collaborative development of new materials in the future. My goal is for teachers and students to work together to generate their own circular classroom content that will support other people learning circular thinking, too.

The Finnish Curriculum already focuses on sustainability and on active citizenship, themes that we really worked on elevating through the activities and reflective elements of the modules. Each module contains three core classroom activities and a series of extra ideas for in-class or take-home enrichment to help get students excited and motivated about the incredible opportunities that the Circular Economy offers us all. Once these have started to be integrated into the learning environment, teachers are encouraged to develop their own collaborative circular classroom tools with colleagues and students and then share them with the world.

Each workbook is developed to help teachers integrate the main concepts of circular thinking into the classroom; no matter what subject area they are already teaching, the Circular Classroom activities are interconnected with collaboration and integration across subjects. From biology to math, language, and philosophy, the activities are universal and applicable to each learning objective in the curriculum.

Module 1: From Linear to Circular Thinking

The first module focused on asking questions about the current linear economy and the possibility and potential of transitioning to a circular one where waste is designed out right from the start. The activities help the students explore what kinds of actions each person can take to help design a future that works better and what potential for solving complex problems a circular future holds. Watch the in-class video below to see the full framing of this topic area.

The learning module activities teach life cycle thinking, learning how to identify natural systems in the world around us and making comparisons around everyday consumption products that we all buy and use. Circularity is presented in different levels of the ecological, industrial, and personal arenas, encouraging students to think locally and globally alike while learning about the role of activities in the economy and how supply chains work.

Module 2: Systems and Sustainability

Module 2 is all about understanding how systems work in the world and what the concept of sustainability is really about. It challenges the students to learn how nature works as well as provides all the life-sustaining services that we all rely on.

Through the activities into systems thinking, the students explore an everyday phenomena to discover the dynamic interconnected relationships that make it possible and uncover what key terms such as 'biodegradable' mean. Extra activities cover what bicycles are and how to calculate each person's ecological footprint.

The activities in this module support learning how individual actions have cumulative impacts, identifying how individual changes can add up to help achieve bigger sustainability wins, and how we can apply aspects of the circular economy to our personal lives. The video above explains the core concepts covered in this module.

Module 3: Design and Creativity

Design is a powerful social influence that impacts every day of our lives. It's also an exciting profession that helps create many of the new industries we are seeing emerge. Creativity is a critical skill for the future, especially for addressing big complex problems like climate change and ocean plastic waste. So, this module is all about activating creative thinking and giving young people the tools to be agents of their own life and the future.

The introductory video blow shows how I unpack what design is and how it affects all of us, why humans design the world to work for the status quo, and how it can be redesigned to make a positive difference and create circular solutions.

All the activities in this module focus on learning to apply creative thinking to complex problems and to discover the power of collaboration and positive outlooks in building a better future.

Educators Support Module

The Educator Support Pack is designed to rapidly transfer knowledge in the areas of the circular economy, systems thinking, and sustainability, along with support the educators' lesson planning while providing connections to the Finnish curriculum. These types of support tools were requested by the educators through the co-design sessions, so we wanted to make sure that they felt supported and equipped to deliver the content in their own unique ways.

The video below explains what is covered and shares a quick intro on how to use the materials in the Circular Classroom modules.

Why the focus on Circular Thinking and Creativity?

The Circular Economy is a growing movement to redesign our global economy from a linear state of unsustainable extraction to a more sustainable and regenerative circular model, where goods and services are designed within beautiful systems that maintain the value of materials and resources over longer periods of time.

In breaking these more abstract and complex subjects down, I created the content for these three modules so that the students can go from the big picture through to their individual actions. This empowers agency and supports identity around the themes to also show that there is an exciting opportunity in engaging with redesigning the problems.

I sought to find ways of genuinely relating it to the creative and curious minds of young adults and shared examples of everyday things to help trigger relationships between their own lives and the bigger world at play around them. The activities are all designed to further support 'in-life' learning outside of the classroom and to provide educators with a suite of resources so that they can design their own lesson plans.

The Disruptive Design Method

I developed the Disruptive Design Method as a scaffolding to support the development of international interventions into existing systems in respectful and game-changing ways. The three-part process of Mining, Landscaping, and Building supports creative changemakers in deeply understanding a problem or phenomenon before they attempt to solve it by diving deep under the obvious parts and seeking out all the experiential information they need to then put together a bird's eye view of the opportunities, issues, and potential arena for change (which is the Landscaping phase). Then, from that, they can build creative interventions that respectfully challenge the status quo or contribute to bright spots that desire to be enhanced (the Building phase).

In this case, the Mining phase was all about understanding what the current knowledge and commitment to the core topic area was, and then building on strengths and contributing new approaches. Ideas were micro-tested during the project development phase through design workshops that I facilitated with 40 Finnish students and teachers.

Through this, I was able to prototype out several of the main activities I had developed as a result of the first round of workshops. During the Building phase, I also ran an ideation session with this mixed group of students and teachers, challenging them to co-create their own activities that would be relevant in the classroom. The students and teachers came up with many brilliant ideas, and several of them have been included as the extra activities in the workbooks, now live on the Circular Classroom website.

I came to the conclusion early on in this project that the key thing is to give people agency around the content, and whilst I have a body of knowledge that I can share, this is just a seed. It's a starting point to encourage and motivate many other people to generate educational content and initiatives on how they are embracing circular thinking and how they bring experiential and reflective thinking about our shared future on the planet into the classroom. I want to encourage all educators and students to work together to create their own Circular Classroom content, and through that, to take action in helping to design a future that works better for all of us. Hopefully, this will help not just Finnish students, but young people around the world to see how they can contribute to a more sustainable, equitable, and effective future through the actions that they take today.

Experiential and phenomena-based learning

The idea of experiential and phenomena-based learning is not new; educational protagonists like Paulo Freire and more recently, Sir Ken Robinson, have been loudly challenging for critical changes to the educational format for decades.

The work of Kolb and other educational theorists have provided many new insights into the learning mind, and it's a surprise we have not seen a full redesign of how we, as a society, educate our young and prepare them for adult life. This is why the Finnish system is so exciting - they are willing to challenge the dominant mode of teaching and bring experiential education to the forefront. Furthermore, teachers are urged to use their initiative to figure out what each student needs to succeed.

You can read more about the main approaches here:

You can access and download all of the content for free on the website:

All the videos in Finnish, Swedish and English can be found here

All the workbooks can be downloaded for free here

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The Circular Classroom: a Free Toolkit for Activating the Circular Economy through Experiential Learning

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Finland is, by many accounts, known as having the world's best education system, thanks to its no-homework, student-centric, interdisciplinary, life-skills teaching approach, and for its commitment to experiential and phenomena- based learning (more on this here, here and here).

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Make your own Copper Patina for Lead and Solder | Chatter Glass

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Make your own Copper Patina for Lead and Solder | Chatter Glass

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Chatter Glass | A WordPress.com site with chatter about stained glass crafts.

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Chatter Glass | A WordPress.com site with chatter about stained glass crafts.

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Iron Oxides Approved by the FDA - Sensient Food Colors : Sensient Food Colors

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Iron Oxides Approved by the FDA - Sensient Food Colors : Sensient Food Colors

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On March 20th, 2015; Red, Yellow and Black Iron Oxides were approved as 'Exempt from Certification'
(i.e. Natural) colors by the FDA for use in soft and hard candy, mints, and chewing gum. This action is in response to a petition filed by Wm. Wrigley Jr. Company.

Natural Colors can often face stability issues, in some cases creating formulation challenges. Iron Oxides
are excellent replacements for synthetic FD&C colors in terms of stability, shade and cost-in-use.

Stability:
Iron Oxides, which have been approved in Europe for use in food for years, are extremely stable. They have no chemical or physical reaction to acid, heat, light, moisture, oils, oxygen, or pH. This makes them ideal for confection applications because of the differing process variables involved.

Shade:

Red Iron Oxide is a very close shade match to FD&C Red #40.

Yellow Iron Oxide is not quite as bright as Yellow #5, but it produces a mustard yellow shade.

Black Iron Oxide is a 'TRUE' black, meaning it completely absorbs all light wave lengths. In contrast a Synthetic blend of Red #40, Yellow #5 and Blue #1 will not absorb all light wavelengths, keeping it from being a 'TRUE' black.

Red, Yellow and Black Iron Oxides can be blended with each other and any other natural color to achieve a wide range of color shades. Because they function as pigments, the door is now open to natural colors for direct contact, solvent-based, confectionery inks.

Cost-in-use:
Iron Oxides are very economical compared not only to other natural colors but also synthetic colors due to their strong tinting strength, which lowers the cost-in-use. Usage levels are self-limiting as long as they are consistent with GMP (Good Manufacturing Practice).

Iron Oxides have similar plating characteristics to a Synthetic Lake, which makes them great for use in compressed tablets and compound coatings. Additionally, the pigments are perfect for panning, hard candy, gummies, liquorice and chewing gum.

Iron Oxides may not be a match for every brand, because consumer perception of them are not as favorable as colors derived from botanical sources. However, they do offer new options that will make natural color conversion for some confection brands more efficient.

Continue to follow my blog for future confection color developments.

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Iron Oxides Approved by the FDA - Sensient Food Colors

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On March 20th, 2015; Red, Yellow and Black Iron Oxides were approved as 'Exempt from Certification' (i.e. Natural) colors by the FDA for use in soft and hard candy, mints, and chewing gum. This action is in response to a petition filed by Wm. Wrigley Jr. Company.

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Make: DIY Projects and Ideas for Makers |

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Make: DIY Projects and Ideas for Makers |

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Magazine that celebrates your right to tweak, hack, and bend any technology to your own will.

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Stained Glass That Breaks All the Rules - The New York Times

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Stained Glass That Breaks All the Rules - The New York Times

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Los Angeles's oldest stained glass studio, Judson, is collaborating with emerging and established artists to modernize a medieval craft.

"Kobe, 2017," a collaboration of Tim Carey's design and fabrication at Judson, Los Angeles's oldest stained glass studio. It will be on view at Forest Lawn starting next week. Credit... Tim Carey and Judson Studios

LOS ANGELES - In 1893, an itinerant plein-airEnglishpainter came to the West Coast to die. At 51, William Lees Judson could look back on a life full of adventure: trans-Atlantic crossings, farming Ontario's plains, fighting under Ulysses S. Grant in the Civil War, Beaux-Arts immersion at Paris's Académie Julian. When his wife died suddenly and his own health soured, doctors advised him to take the "California cure" and spend his last days in the Golden State's hot, dry air.

"Instead, he lived another 35 years, started U.S.C.'s College of Fine Arts in this building, and helped launch the Arts and Crafts movement," his great-great-grandchild David Judson said recently at the stained glass studio the elder Judson founded in 1897.

From the studio in Highland Park, with its views of the San Gabriel Mountains and Arroyo Seco, its original crown moldings, terra cotta portico, light fixtures and over 500 types of colored glass on display - a palette of sorts for the studio's artisans to choose from - one can nearly picture Los Angeles as the sleepy cow town it once was.

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In the studio in Highland Park, a stained glass color palette hanging over a panel for New Mount Carmel Monastery in Meeteetse, Wyo. Judson Studios is steeped in a tradition of leaded glass, but also excels at a process which fuses multiple pieces and forms new colors. Credit... Yudi Ela for The New York Times

Five generations of Judsons would fabricate stained glass windows for Craftsman homes in Pasadena and Hollywood, including Frank Lloyd Wright's Ennis and Hollyhock Houses - the Hollyhock is a UNESCO site whose windows were angle-heavy glass abstractions that Wright called "light screens" - as well as glass murals at Grauman's Egyptian Theater, the globe chandelier at the historic Central Public Library in Los Angeles and countless churches, synagogues and museums.

Beyond California, the studio's best known work includes the space-age glass at the U.S. Air Force Academy's Cadet Chapel, a midcentury marvel in Colorado; and the 100-foot-wide, $3.4 million fused-glass window at the Church of the Resurrection in Leawood, Kan. Artisans created 30,000 pounds of 17 colored glass pieces for the Burj Al-Arab hotel's lavish atrium fountain in Dubai - and bronze-colored glass for Kelly Wearstler-designed cabinets and sliced-agate glass door panels for Christina Aguilera.

Stained glass was born in the churches of medieval Europe and is mouth blown, then hand-cut and assembled with strips of lead. Judson is steeped in the tradition of leaded glass, but also excels at a process in which glass is heated to more than 1,000 degrees Fahrenheit, which fuses multiple pieces and forms new colors. The most expensive color is pink, Judson said, because it is made using gold flakes.

The studio has over the last four years teamed up with a cadre of local emerging and established artists who designedmurals, streetscapes, even sculpture, which Judson fabricated for a debut show that was scuttled because of the pandemic.

"World War I, the 1918 pandemic, World War II, we were open for all of that," said Judson, who closed for three months last year because of Covid-19. (The staff was cut to 18 employees from 30.)

This pause presented something unexpected which helped the show come to fruition: time to perfect the multiyear, labor-intensive undertakings, which take eight to 10 hours to design and paint per square foot. Next week, those pieces that the artists started years ago will be unveiled in the debut exhibition - "Judson Studios: Stained Glass From Gothic to Street Style" - at Forest Lawn, a museum that doubles as a memorial cemetery and park, and is also known as a Los Angeles landmark.

Glass portraits of a deified Kobe Bryant, gothic script mosaics and abstract sculptures are among the fusions from Tim Carey, who worked with the Mexican-Italian artist Narcissus Quagliata on the Resurrection window; David Flores, known for Pop Art murals and commercial work; Miles MacGregor, a.k.a. EL MAC, an acrylic painter with murals in Cuba and Cambodia; Marco Zamora, known for paintings of the blue-collar side of town; and the experimental filmmaker Alice Wang, whose work is influenced by the La Brea Tar Pits.

The collaborations break "all the rules of stained glass," said James Fishburne, the director of the Forest Lawn Museum. The venue breaks rules too, said Zamora, who called Forest Lawn an "unexpected place to show" in an "unexpected" year.

The show, which is free, runs from April 28 to Sept. 12 and includes nearly 100 original pieces. It also reveals the medieval stained glass built into Forest Lawn's walls, including some designed by Albrecht Dürer. Many of the glass pieces in Forest Lawn's collection that will be part of the show were created between the 12th and 16th centuries in France and Germany and bought from the collection of William Randolph Hearst.

"We're a hidden gem and we're trying to unhide it," Fishburne said.

Judson Studios began working with Forest Lawn in 1920 on a group of ceiling lights and windows for its Great Mausoleum.

There are many steps in creating windows, Judson explained, and that means ample room for errors. That was especially pointed for what may be the studio's most ambitious project: "Pagoda," a massive glass dome from the Taiwanese-American fine artist James Jean. Design, framing, materials, construction, data analysis and structural engineering brought the out-of-pocket cost to $1.5 million.

"When I started working with Judson, we used the technique of water-jet cutting and bringing in airbrushing and building 3-D elements," said Jean, who worked with Judson on an earlier project, a glass sculpture, " Gaia," which is now at a South Korean museum. The partnership led to the immersive "Pagoda" that allows viewers "to step in and be completely enveloped in color and light and it will shift and change as the light changes," Jean said. Panels from that work will be shown by late summer.

A recent trip to the cemetery, perched on a hill overlooking the urban jungle, was a scene of juxtapositions: Fishburne is ready to show off the museum, a hodgepodge of a Frederic Remington cowboy, Mark Twain maquette, Easter Island moai and classical reproduction, while horse-drawn funeral carriages and mourners are just outside.That scene was a somber reminder of the place and time that makes Fishburne remark that he "hopes the public comes."

"Now that we're opening, it's exciting, but you don't know what to expect," said Fishburne.

Still, having something to look forward to is a major unifier.

"We're basically graffiti, street artists, so to have us come through to Forest Lawn, it feels really good," said the artist Flores, who grew up in Tulare, Calif., where "there was no stained glass," and fell in love with the medium on trips to Spain during long contemplations in medieval churches.

Flores at one point spent two days a week at the studio learning to cut and snap glass into form with Judson's artisans, whom he credits with immense patience.

"There's a special type of discipline needed for this kind of work," he said, a resolve he admits he lacks. "I hope people show up and give it a chance."

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Los Angeles's oldest stained glass studio, Judson, is collaborating with emerging and established artists to modernize a medieval craft. LOS ANGELES - In 1893, an itinerant plein-airEnglishpainter came to the West Coast to die. At 51, William Lees Judson could look back on a life full of adventure: trans-Atlantic crossings, farming Ontario's plains, fighting under Ulysses S.

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14.1 Groundwater and Aquifers – Physical Geology

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14.1 Groundwater and Aquifers – Physical Geology

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Groundwater is stored in the open spaces within rocks and within unconsolidated sediments. Rocks and sediments near the surface are under less pressure than those at significant depth and therefore tend to have more open space. For this reason, and because it's expensive to drill deep wells, most of the groundwater that is accessed by individual users is within the first 100 m of the surface. Some municipal, agricultural, and industrial groundwater users get their water from greater depth, but deeper groundwater tends to be of lower quality than shallow groundwater, so there is a limit as to how deep we can go.

Porosity is the percentage of open space within an unconsolidated sediment or a rock. Primary porosity is represented by the spaces between grains in a sediment or sedimentary rock. Secondary porosity is porosity that has developed after the rock has formed. It can include fracture porosity - space within fractures in any kind of rock. Some volcanic rock has a special type of porosity related to vesicles, and some limestone has extra porosity related to cavities within fossils.

Porosity is expressed as a percentage calculated from the volume of open space in a rock compared with the total volume of rock. The typical ranges in porosity of a number of different geological materials are shown in Figure 14.2. Unconsolidated sediments tend to have higher porosity than consolidated ones because they have no cement, and most have not been strongly compressed. Finer-grained materials (e.g., silt and clay) tend to have greater porosity - some as high as 70% - than coarser materials (e.g., gravel). Primary porosity tends to be higher in well-sorted sediments compared to poorly sorted sediments, where there is a range of smaller particles to fill the spaces made by the larger particles. Glacial till, which has a wide range of grain sizes and is typically formed under compression beneath glacial ice, has relatively low porosity.

Consolidation and cementation during the process of lithification of unconsolidated sediments into sedimentary rocks reduces primary porosity. Sedimentary rocks generally have porosities in the range of 10% to 30%, some of which may be secondary (fracture) porosity. The grain size, sorting, compaction, and degree of cementation of the rocks all influence primary porosity. For example, poorly sorted and well-cemented sandstone and well-compressed mudstone can have very low porosity. Igneous or metamorphic rocks have the lowest primary porosity because they commonly form at depth and have interlocking crystals. Most of their porosity comes in the form of secondary porosity in fractures. Of the consolidated rocks, well-fractured volcanic rocks and limestone that has cavernous openings produced by dissolution have the highest potential porosity, while intrusive igneous and metamorphic rocks, which formed under great pressure, have the lowest.

Porosity is a measure of how much water can be stored in geological materials. Almost all rocks contain some porosity and therefore contain groundwater. Groundwater is found under your feet and everywhere on the planet. Considering that sedimentary rocks and unconsolidated sediments cover about 75% of the continental crust with an average thickness of a few hundred metres, and that they are likely to have around 20% porosity on average, it is easy to see that a huge volume of water can be stored in the ground.

Porosity is a description of how much space there could be to hold water under the ground, and permeability describes how those pores are shaped and interconnected. This determines how easy it is for water to flow from one pore to the next. Larger pores mean there is less friction between flowing water and the sides of the pores. Smaller pores mean more friction along pore walls, but also more twists and turns for the water to have to flow-through. A permeable material has a greater number of larger, well-connected pores spaces, whereas an impermeable material has fewer, smaller pores that are poorly connected. Permeability is the most important variable in groundwater. Permeability describes how easily water can flow through the rock or unconsolidated sediment and how easy it will be to extract the water for our purposes. The characteristic of permeability of a geological material is quantified by geoscientists and engineers using a number of different units, but the most common is the hydraulic conductivity. The symbol used for hydraulic conductivity is K. Although hydraulic conductivity can be expressed in a range of different units, in this book, we will always use m/s.

The materials in Figure 14.3 show that there is a wide range of permeability in geological materials from 10-12 m/s (0.000000000001 m/s) to around 1 m/s. Unconsolidated materials are generally more permeable than the corresponding rocks (compare sand with sandstone, for example), and the coarser materials are much more permeable than the finer ones. The least permeable rocks are unfractured intrusive igneous and metamorphic rocks, followed by unfractured mudstone, sandstone, and limestone. The permeability of sandstone can vary widely depending on the degree of sorting and the amount of cement that is present. Fractured igneous and metamorphic rocks, and especially fractured volcanic rocks, can be highly permeable, as can limestone that has been dissolved along fractures and bedding planes to create solutional openings.

Both sand and clay deposits (and sandstone and mudstone) are quite porous (30% to 50% for sand and 40% to 70% for silt and clay), but while sand can be quite permeable, clay and mudstone are not.

The surface of most silicate mineral grains has a slight negative charge due to imperfections in the mineral structure. Water (H2O) is a polar molecule. This means that while it has no overall electrical charge, one side of the molecule has a slight positive charge (the side with the two hydrogens), compared to a slight negative charge on the other side. Water is strongly attracted to all mineral grains and water within that bound water layer (a few microns around each grain) is not able to move and flow along with the rest of the groundwater. In the lower diagrams shown here, the bound water is represented by dark blue lines around each grain and the water that can move is light blue. In the sand, there is still a lot of water that is able to move through the sediment, but in the clay/silt almost all of the water is held tightly to the grains and this reduces the permeability. [SE]

We have now seen that there is a wide range of porosity in geological materials and an even wider range of permeability. Groundwater exists everywhere there is porosity. However, whether that groundwater is able to flow in significant quantities depends on the permeability. An aquifer is defined as a body of rock or unconsolidated sediment that has sufficient permeability to allow water to flow through it. Unconsolidated materials like gravel, sand, and even silt make relatively good aquifers, as do rocks like sandstone. Other rocks can be good aquifers if they are well fractured. An aquitard is a body that does not allow transmission of a significant amount of water, such as a clay, a till, or a poorly fractured igneous or metamorphic rock. These are relative terms, not absolute, and are usually defined based on someone's desire to pump groundwater; what is an aquifer to someone who does not need a lot of water, may be an aquitard to someone else who does. An aquifer that is exposed at the ground surface is called an unconfined aquifer. An aquifer where there is a lower permeability material between the aquifer and the ground surface is known as a confined aquifer, and the aquitard separating ground surface and the aquifer is known as the confining layer.

Figure 14.4 shows a cross-section of a series of rocks and unconsolidated materials, some of which might serve as aquifers and others as aquitards or confining layers. The granite is much less permeable than the other materials, and so is an aquitard in this context. The yellow layer is very permeable and would make an ideal aquifer. The overlying grey layer is a confining layer.

The upper buff-coloured layer ( K = 10-2 m/s) does not have a confining layer and is an unconfined aquifer. The yellow layer ( K = 10-1 m/s) is "confined" by the confining layer ( K = 10-4 m/s), and is a confined aquifer. The confined aquifer gets most of its water from the upper part of the hill where it is exposed at the surface, and relatively little by seepage through the fine silt layer.

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Groundwater is stored in the open spaces within rocks and within unconsolidated sediments. Rocks and sediments near the surface are under less pressure than those at significant depth and therefore tend to have more open space.

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How Hydraulic Fracturing Works | National Geographic Society

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How Hydraulic Fracturing Works | National Geographic Society

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The video above is from the March 2013 iPad edition of National Geographic magazine.

Hydraulic fracturing, or fracking, is a drilling method used to extract petroleum (oil) or natural gas from deep in the Earth. In the fracking process, cracks in and below the Earth's surface are opened and widened by injecting water, chemicals, and sand at high pressure.

Some resources extracted through fracking are called "tight oil" or "tight gas," because these pockets of fossil fuels are tightly trapped in hard shale rock formations. By accessing tight oil and tight gas, the sophisticated technologies used in fracking are rapidly expanding petroleum and natural gas production in the United States.

This video explains the technology of fracking using the example of the Iverson oil well, which drills into the Bakken shale formation near Williston, North Dakota.

A handful of other nations are investing in hydraulic fracturing to extract petroleum and natural gas.

Fracking is used to extract natural gas from the Montney shale formation in Alberta and British Columbia, Canada.

Fracking is used to extract natural gas from the Sichuan basin in China.

Fracking is used to extract petroleum from the Taranaki shale formation in New Zealand.

One of the most active sites of fracking for oil is the Bakken shale formation, stretching from western North Dakota and Montana through the southern part of the Canadian province of Saskatchewan.

Fracking is used to extract natural gas from the Marcellus shale formation in the northern Appalachian Basin, extending through the states of New York, Pennsylvania, Ohio, Maryland, West Virginia, and Virginia.

One of the first places hydraulic fracturing technology was used was the Barnett shale formation in northern Texas.

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Caryl-Sue, National Geographic Society

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Samantha Zuhlke, National Geographic Society

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Caryl-Sue, National Geographic Society

Last Updated

April 1, 2013

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A handful of other nations are investing in hydraulic fracturing to extract petroleum and natural gas.

Fracking is used to extract natural gas from the Montney shale formation in Alberta and British Columbia, Canada.

Fracking is used to extract natural gas from the Sichuan basin in China.

Fracking is used to extract petroleum from the Taranaki shale formation in New Zealand.

One of the most active sites of fracking for oil is the Bakken shale formation, stretching from western North Dakota and Montana through the southern part of the Canadian province of Saskatchewan.

Fracking is used to extract natural gas from the Marcellus shale formation in the northern Appalachian Basin, extending through the states of New York, Pennsylvania, Ohio, Maryland, West Virginia, and Virginia.

One of the first places hydraulic fracturing technology was used was the Barnett shale formation in northern Texas.

Writer

Caryl-Sue, National Geographic Society

Editor

Samantha Zuhlke, National Geographic Society

Producer

Caryl-Sue, National Geographic Society

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The video above is from the March 2013 iPad edition of National Geographic magazine. Hydraulic fracturing, or fracking, is a drilling method used to extract petroleum (oil) or natural gas from deep in the Earth. In the fracking process, cracks in and below the Earth's surface are opened and widened by injecting water, chemicals, and sand at high pressure.

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Are Orbeez Biodegradable and How to Dispose of Them? | KidsBaron

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Are Orbeez Biodegradable and How to Dispose of Them? | KidsBaron

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Are Orbeez Biodegradable and How to Dispose of Them? | KidsBaron

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The best thing of all is that Orbeez are absolutely safe to play with. They are non-toxic and even if your kids swallow one bead, you should not have...

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Shrinky Dinks - Gelfand Center - Carnegie Mellon University

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Shrinky Dinks - Gelfand Center - Carnegie Mellon University

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Shrinky Dinks® are an art/craft toy invented in 1973 by Betty Morris of Brookfield, Wisconsin. These toys reached the height of their popularity in the 1980s. Shrinky Dinks® consist of thin, flexible sheets of polystyrene, a common polymer. Prior to heating, the thin, flexible sheets can be colored and cut into shapes. When heated in the oven, the plastic shrinks to approximately 1/3 of its original size, and becomes 9 times thicker and more rigid, while retaining the colored design.

Shrinky Dinks® can be purchased from a number of retailers such as JoAnn™ Fabrics, Michaels©, etc. However, they can also be easily obtained from polystyrene containers (recycled plastic #6), especially the clear "clamshells" used for sandwiches, salads, etc. These containers can be cut, sanded, and decorated just like Shrinky Dinks®. The special properties of this product are due to the manufacturing process used to form polystyrene into thin sheets.

The properties of all solid materials, including polymers, depend on their processing history. The temperature, method, and speed of processing are key variables. Processing refers to the technology used to convert a raw material (a polymer, for example) into an article of a certain shape. Most plastic films and sheets are produced by extrusion.

In the extrusion process, the raw material is conveyed down a heated barrel by a rotating screw. The material melts as it proceeds down the barrel and is forced through a die which gives it its final shape. The raw polystyrene is melted at 190°C and extruded through a slot die. The resulting film exits the die at a temperature above its glassy transition point (around 100°C). This means the material is soft and rubbery. The forced flow through the die causes stretching in the direction of flow, but to produce a biaxially stretched film, further stretching in the direction perpendicular to the machine direction is required. The stretched film is then taken up by several rollers. These rollers are usually chilled to quickly cool (quench) the rubbery film.

The rapid cooling of the film maintains the stretched shape. When the film is heated, the polystyrene chains return to their more random configuration. The polystyrene chains are said to "remember" their most stable (random) configuration, even though they can be "frozen" into a less stable configuration by rapid cooling during manufacture. The behavior of the biaxially-oriented polystyrene is unusual. Most objects soften or melt when heated, or sometimes they decompose if the temperature is high. The polystyrene shrinks dramatically, but its mass stays the same. The decrease in the area is compensated for by an increase in the thickness.

The following experiment demonstrates the phenomenon described above.

SAFETY NOTE: Adult supervision is required during cutting and baking!

Supplies needed:

Shrinky Dinks® plastic sheets

Colored pencils or permanent markers

Scissors and paper punch

Toaster oven or conventional oven

Aluminum foil or brown paper

Procedure:

1. Design and decorate the plastic sheets as desired. Colored pencils can be used on the frosted (pre-sanded) product. If using the transparent (non-sanded) sheets, permanent markers will be needed.

2. Pieces can be cut before or after decorating. Cut sheets in circles or shapes as smoothly as possible. Edges become sharper after shrinking, so round corners a little. You can create fancy edges with designer scissors, or use small manicure scissors to do detailed cut work.

3. Punch a hole before baking. Remember that the hole will shrink, so make it large enough for your application. A standard size paper punch is ideal for most projects.

4. Bake in a toaster oven or conventional oven. Shrinky Dinks® do not work with microwave ovens! Place Shrinky Dinks® pieces, colored side up, on tray or cookie sheet covered with foil or brown paper. Heat at 325°F (163°C) for 1 to 3 minutes. Watch as the Shrinky Dinks® shrink. After the pieces lay flat, allow an additional 30 seconds of baking time to complete the process.

5. Remove from the oven and lightly press down to flatten completely. Occasionally a piece may stick to itself. If this happens, reach into the oven carefully, and pull apart gently with a knife.

6. Allow pieces to cool before handling (about 3-5 minutes).

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Shrinky Dinks - Gelfand Center - Carnegie Mellon University

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Shrinky Dinks® are an art/craft toy invented in 1973 by Betty Morris of Brookfield, Wisconsin. These toys reached the height of their popularity in the 1980s. Shrinky Dinks® consist of thin, flexible sheets of polystyrene, a common polymer. Prior to heating, the thin, flexible sheets can be colored and cut into shapes.

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Super-Absorbing Polymer Powder - Gelfand Center - Carnegie Mellon University

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Super-Absorbing Polymer Powder - Gelfand Center - Carnegie Mellon University

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Sodium polyacrylate is an example of a super-absorbing polymer. It is a cross-linked (network) polymer that contains sodium atoms. It absorbs water by a process called osmosis. When the (sodium-containing) polymer is placed in contact with water, there is a tendency for the sodium to distribute equally between the network and the water. That means, some of the sodium atoms want to leave the network and move to the water. When these sodium atoms leave, they are replaced with water molecules. Water swells the polymer network to try to keep the sodium concentration balanced between the polymer and the water. The cross-links that connect the chains together prevent them from dissolving/breaking apart in the water. Sodium polyacrylate can absorb 800 times its weight in distilled water, but only 300 times its weight in tap water, since tap water contains some sodium, calcium and other mineral salts.

The experiment below will illustrate this phenomenon.

Supplies needed:

Sodium Polyacrylate powder (available from Flinn Scientific Inc.)

PolySnow™ powder (available from Flinn Scientific Inc.)

2 - 10 oz clear plastic cups

Distilled water

Squeeze bottles or containers of known volume

Salt

Procedure:

1. Place 1/8 teaspoon of sodium polyacrylate powder in a plastic cup
2. Place 1/4 teaspoon of PolySnow™ in another cup.

3. Using a 4 oz. squeeze bottle, slowly add distilled water to each of the powders, stirring gently; letting each powder absorb the water before adding more.

4. Continue adding water to both cups until absorption seems to stop.

Observations:

Gently touch the polymers in the cups. What do they look and feel like?

Are they a solid or a liquid?

How does PolySnow™ differ in appearance from the sodium polyacrylate?

Does PolySnow™ absorb as much water as the sodium polyacrylate?

Add a teaspoon of table salt (NaCl) or calcium chloride to both the swollen polymers. Observe what happens?

Did the addition of salt have the same effect on the PolySnow™ as with the sodium polyacrylate?

Super-absorber Power Calculations:

In the case of the sodium polyacrylate, 1/8 teaspoon of the powdered polymer weighs 0.35 grams; 4 oz. of water weigh 120 grams. How many times its own weight in water did the polymer absorb?

Answer: 120g/0.35g=342.86 or approximately 343 times its weight!

Sodium polyacrylate and PolySnow™ are both forms of the same material and are both examples of super-absorbing polymers. The amount of cross-linking, called the crosslink density, determines the properties of the super absorber. Sodium polyacrylate and PolySnow™ differ in the amount of cross-linking. Sodium polyacrylate has fewer cross-links, and therefore can absorb more water than the PolySnow™. PolySnow™ gets its name from the fact that, within a certain concentration range, it absorbs water to form not the usual gel, but white particles that resemble snowflakes.

Sodium polyacrylate is the main ingredient in baby diapers used to "keep baby dry". It can absorb about 30 times its own weight in urine. An extension of this experiment involves taking a baby diaper apart to determine which part of the diaper "keeps baby dry".

Addition of salts of sodium or calcium reverses the swelling process. Water is no longer needed inside the polymer to balance the salt concentration, so the structure collapses or deflates.

SAFETY NOTE:

Polyacrylate is non-toxic. It is, however, irritating to the eye and nasal membranes. Always wear chemical splash goggles when using this material. The gelled material can be disposed of in the trash. Do not put it in the sink, as it may clog the drain!

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Super-Absorbing Polymer Powder - Gelfand Center - Carnegie Mellon University

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Sodium polyacrylate is an example of a super-absorbing polymer. It is a cross-linked (network) polymer that contains sodium atoms. It absorbs water by a process called osmosis. When the (sodium-containing) polymer is placed in contact with water, there is a tendency for the sodium to distribute equally between the network and the water.

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A Materials Recovery Facility, MRF, is where recycling goes after it is picked up by a hauler. Multiple haulers can use the same MRF, as they are usually not hauler specific facilities. The visual below shows the process of how a mixed recycling stream is sorted at a MRF.

1) Recycling is picked up throughout an area at residential homes and businesses by a hauler.

2) Various haulers in the area then bring the recycling they have collected to a Materials Recovery Facility.

3) At the Materials Recovery Facility, the recycling gets loaded onto a conveyor belt where workers manually remove contamination. The contaminates usually are plastic film like plastic bags and candy wrappers, but also wires, textiles, and organics. This is an important step because if not removed, these items can cause severe damage to the sorting equipment.

4) Cardboard and paper products are the first recyclables to be separated. As the recycling stream moves down the conveyor belt, large wheels divert and propel the cardboard and paper up as the heavier items fall through.

5) As the lightweight paper materials is sorted out, the remaining glass, metals, and plastics continue down the conveyor belt.

6) The metals are the next material to be removed. Large magnets collect steel cans and other magnetic metal as it passes by.

7) After the steel is drawn out by magnets, an eddy current is created by a magnet field which repels aluminum and other non-ferrous metals into a separate bin.

8) Glass bottles and jars are then separated from the remaining plastics using a density blower. A jet air stream hits each item, blowing the lightweight plastics onto a different route.

9) The heavier glass does not get redirected by the air and continues down the original conveyor belt to be hammered or grinded into finely crushed glass, known as cullet.

10) The remaining plastic is sorted by optical lasers that determine the resin type and sort each plastic into its appropriate bin.

Once the separating process is complete there are six different collections of recyclables: cardboard and paper, steel, aluminum, glass, and plastic. Each material is compacted and bailed and sent to specific materials recycling facilities where they are further processed in order to become suitable for use in manufacturing.

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A Materials Recovery Facility, MRF, is where recycling goes after it is picked up by a hauler. Multiple haulers can use the same MRF, as they are usually not hauler specific facilities. The visual below shows the process of how a mixed recycling stream is sorted at a MRF.

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Assignments

Design a 3D mold.machine it, and use it to cast parts

Machine it, and use it to cast parts

Review the safety data sheets for each of your molding and casting materials.

So in this weel we are going to make molds and cast materials. Moulding is a commonly used manufacturing process that used for multimodelling or long life processes.A mold or mould is a hollowed-out block that is filled with a liquid or pliable material such as plastic, glass, metal, or ceramic raw material.[2] The liquid hardens or sets inside the mold, adopting its shape. A mold is the counterpart to a cast. The very common bi-valve molding process uses two molds, one for each half of the object. So let's see different moulding processes...

Rotational Molding

Rotational Molding Rotational Molding, also called rotomolding, is a manufacturing process for producing large hollow parts and products by placing a powder or liquid resin into a metal mold and rotating it in an oven until the resin coats the inside of the mold. The constant rotation of the mold creates centrifugal force forming even-walled products. Once the mold cools, the hardened plastic is removed from the mold.

Very little material is wasted during the process, and excess material is often re-used, making it economical and environmentally friendly.

Injection Molding

Injection molding is the process of making custom plastic parts by injecting molten plastic material at high pressure into a metal mold. Just like other forms of plastic molding, after the molten plastic is injected into the mold, the mold is cooled and opened to reveal a solid plastic part.

The process is similar to a Jello mold which is filled then cooled to create the final product.

Blow Molding

Blow molding is a method of making hollow, thin-walled, custom plastic parts. It is primarily used for making products with a uniform wall thickness and where the shape is important. The process is based upon the same principle as glass blowing.

Blow molding machines heat up plastic and inject air blowing up the hot plastic like a balloon. The plastic is blown into a mold and as it expands, it presses against the walls of the mold taking its shape. After the plastic "balloon" fills the mold, it is cooled and hardened, and the part is ejected. The whole process takes less than two minutes so an average 12 hour day can produce around 1440 pieces

Compression Molding

Compression molding is done exactly like the name suggests. A heated plastic material is placed into a heated mold and then pressed into a specific shape. Usually, the plastic comes in sheets, but can also be in bulk. Once the plastic is compressed into the right shape, the heating process ensures that the plastic retains maximum strength. The final steps in this process involve cooling, trimming, and then removing the plastic part from the mold.

Extrusion Molding

Extrusion molding is similar to injection molding except that a long continuous shape is produced. Another difference in extrusion molding is that the process uses a "die" not a "mold." Extruded parts are made by squeezing hot raw material through a custom die. A simplistic visualization would be like squeezing Play Doh through a shaped hole.

While other forms of molding use extrusion to get the plastic resins into a mold, this process extrudes the melted plastic directly into a die. The die shape, not a mold, determines the shape of the final product.

Thermoforming

hermoforming is a manufacturing process where a plastic sheet called thermoplastic is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product.Thermoplastic comes in a wide variety of materials, colors, finishes, and thickness.

Thermoforming uses several different types of molds and processes in order to achieve the final product. To create 3D products, the mold is typically a single 3D form made out of aluminum. Because thermoforming uses low pressures, molds can be produced for a low cost using inexpensive materials.(Source:https://fibertechinc.net/custom-rotational-molding/a-simple-guide-to-plastic-molding/)

Designing 3D mold

So for molding this week, have chose to design a "Ghost" face in fusion360.I started the work woth a rough sketch in fusion

Extruded the sketech according to the shape I needed to the thickness of 20mm.

Now add fillet of 3mm to eyes and nose

Now the Ghost face is done. Now we need to make the background box. For that make a box and offset to 3mm

Now extrude it to fill the shape.

Now I need to make an .stl file to complete the work. For that Select the Make option and click 3D print. Now select the body and click on "Preview mesh". After that click Ok.

Save the .stl file to desired folder and load it to fab modules. Now we have to set up the machine for milling.
You can download the desigmn files from Here.

Setting-Up Modella

For milling, we are going to use a "1/8 inch" ball end 4 flute bit

Now take a wax block and attach double sided tape to the back of the wax block

Now stick it on to the bed of the CNC. Set the bit like we did in Week 5.

Fab Modules

Open fab modules for modella MDX20 by following these steps

Select file format (mesh .stl)

Select machine as "Roland MDX-20 Mill"

click "make rml"

Now we have to upload the .stl

Select "load stl" and select the required file

Select process as "mm, 1/8, wax, rough"

Select "make png"

Select "make path"

Select "make rml"

Select "send it"

Now we can see the machine has started milling

After finishing the rouhcut, we have to start the finishing cut. So follow below steps

change bit process to "mm, 1/8, wax, finish"

select "make path"

select "make rml"

Select "send it"

machine start the work again. After finishing, it will look like this

There was a miske in the designing part. I did'nt leave a top cavity for filling the resin. So I had to make a boundary for the filling of resin

Preparing resin

Now we have to create a negetive mold. For that we take a smooth cast

there are two parts of resin. Part A and Part B. The proportion to mix both of them is "1:1". But first we need to measure the amount of resin needed for the negetive mold making. For that pour some water into the mold and pour it back to the glass and mark the level.

Now pour equal amount of Part A and Part B of the resin into the cup

Now mix the well and pour into the mold. I used a hand dril attached with a acrylic rod to stir up the mixture. Because it was difficult to do with hands

Pour the resin into the mold..

Tap it to the ground so that the air bubbles come up. Wait for 6 hour in order to set the resins.

Please care full while you design you design. Because it can be very trick when it comes to mold. So after waiting for about 6 hours the mold is ready to use. Remove the negetive mold from the wax mold.

The first atempt was a failure. The ratio I mixed the molding resin was wrong and I got an in-complete mold. So tried again with correct ratio. this tome I got it correct

Now I need to cast the oringinal shape..

So we are goint to cast the shape of our "Ghost". For that I took Easy cast epoxy resin

It also have a mixing ratio in which we have to mix the resins. It specifically said that the ratio is 2:1 accoring to grams. So first I look some water in the mold and weight it on the weing machine.

After that I accuratly measure the required resin. I took some more than actual weight...

I mix both parts and stir it using a stick

Now it is mixed very well. Now pour it into the mold that created before (Ghost mold).

Now wait it to settle down and cure. Accoring to datasheet it will take about 6 hours to get cure. But it took almost 12 hour to hardendown to the solid piece. Afer curing, I gently remove the part from the mold.

Hero Shot

Use gloves before using molding and casting agents.

Do not use work table for making molds and casts.

Don't depend on guess to mix the resins.

Group Assignment

Review the safety data sheets for each of your molding and casting materials, then make and compare test casts with each of them

Smooth Cast

The Smooth-Cast™ 300 Series of liquid plastics are ultra-low viscosity casting resins that yield castings that are bright white and virtually bubble free. Vacuum degassing is not necessary. They offer the convenience of a 1A:1B by volume or 100A:90B by weight mix ratio. The differences between them are pot life and demold time

Instructions

Safety - Materials should be stored and used in a warm environment (73° F / 23° C). These products have a limited shelf life and should be used as soon as possible. All liquid urethanes are moisture sensitive and will absorb atmospheric moisture. Mixing tools and containers should be clean and made of metal, glass or plastic. Mixing should be done in a well-ventilated area. Wear safety glasses, long sleeves and rubber gloves to minimize contamination risk. Because no two applications are quite the same, a small test application to determine suitability for your project is recommended if performance of this material is in question.

Applying A Release Agent - A release agent is necessary to facilitate demolding when casting into or over most surfaces. Use a release agent made specifically for mold making (Universal® Mold Release or Mann's Ease Release® 200 available from Smooth-On or your Smooth-On distributor). A liberal coat of release agent should be applied onto all surfaces that will contact the plastic.

IMPORTANT:To ensure thorough coverage, apply release and brush with a soft brush over all surfaces. Follow with a light mist coating and let the release agent dry for 30 minutes. Smooth-On silicone rubber molds usually do not require a release agent unless casting silicone into the mold. Applying a release agent will prolong the life of the mold.

MEASURING & MIXING... Liquid urethanes are moisture sensitive and will absorb atmospheric moisture. Mixing tools and containers should be clean and made of metal, glass or plastic. Materials should be stored and used in a warm environment (73°F/23°C). Stir or shake both Part A & Part B thoroughly before dispensing. After dispensing equal amounts of Parts A and B into mixing container (100A:90B by weight) and mix thoroughly. Stir deliberately making sure that you scrape the sides and bottom of the mixing container several times. Be careful not to splash low viscosity material out of the container.

POURING, CURING & PERFORMANCE... Pour your mixture in a single spot at the lowest point of the containment field and let the mixture seek its level. This will help minimize air entrapment.Best results are obtained using a pressure casting technique. After pouring the mixed compound, the entire casting assembly (mold, dam structure, etc.) is placed in a pressure chamber and subjected to 60 PSI (4.2 kg/cm2) air pressure for the full cure time of the material.Use this product with at least room size ventilation or in proximity to a forced outlet air vent and do not inhale/breath fumes. Fumes, which may be visible with a significant mass concentration, will quickly dissipate with adequate ventilation. Castings with significant mass may be hot to the touch and irritate skin immediately following cure. Let casting cool to room temperature before handling.

(Source:https://www.smooth-on.com/products/smooth-cast-300/)

Inhalation: Remove source(s) of contamination and move victim to fresh air. If breathing has stopped, give artificial respiration, then oxygen if needed. Contact physician immediately.

Eye Contact: Flush eyes with plenty of water. If irritation persists, seek medical attention. Skin Contact: In case of skin contact, wash thoroughly with soap and water.

Ingestion: Do not induce vomiting unless instructed by a physician. Never give anything by mouth to an unconscious person.

The material safety data sheet you find Here

Casting Resin

For casting we are using Aditya Easy Cast Transparent Epoxy Resin - 33-750gm. It is very easy to use.

Description

Aditya Transparent Epoxy Resin is specially created for embedding and making small statue's casting. Ratio in Grams not ml....A Part 100 grams : B Part 50 Grams

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Assignments Design a 3D mold.machine it, and use it to cast parts Machine it, and use it to cast parts Review the safety data sheets for each of your molding and casting materials. So in this weel we are going to make molds and cast materials.

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Build robots, solve real world problems, and work next to scientists at cutting edge DoD Laboratories and Centers.

Did you know that DoD STEM offers opportunities for potential students, educators, and the current workforce to work on cutting-edge projects solving real-world problems alongside DoD STEM Professionals, including scientists, engineers, manufacturers, and more! Check out these opportunities below.

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Did you know that DoD STEM offers opportunities for potential students, educators, and the current workforce to work on cutting-edge projects solving real-world problems alongside DoD STEM Professionals, including scientists, engineers, manufacturers, and more! Check out these opportunities below. Your filter or search returned no results. Please try again.

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Featured Video

Color Writing: Analyzing Fuel to Keep Jets Flying High

Using a process called chromatography (or color writing), chemists are able to break out all the components in a mixture. Dye makers use this technique to separate the different pigments in their dyes, but the process is also valuable in crime and environmental research. In an Air Force research laboratory in Dayton, Ohio, scientists are using chromatography to analyze the hundreds of different compounds in jet fuel. Most are hydrocarbon chains-carbons with hydrogens-and jet fuels need to be a precise blend of these. Using chromatography, chemists are helping to develop more efficient fuels for the Air Force. "I like what I do because I can see where my research goes," says research chemist Milissa Lawson. "I can look up in the sky and see a jet plane and you know that some of what you did is what is on that plane."

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Featured Video Using a process called chromatography (or color writing), chemists are able to break out all the components in a mixture. Dye makers use this technique to separate the different pigments in their dyes, but the process is also valuable in crime and environmental research.

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Waste and recycling information, events, commerce and education

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ASM International is the world's largest association of materials-centric engineers and scientists. We are dedicated to informing, educating, and connecting the materials community to solve problems and stimulate innovation around the world.

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Alcohol Chemistry(19) Analytical Chemistry(9) Aroma Chemistry(21) Atmospheric Chemistry(13) Biochemistry(70) Biology(13) Book(5) C&EN(84) Chemical Concerns(9) Chemical Reactions(6) Chemical Warfare(5) Chemistry Advent(5) Chemistry History(30) Chemistry in the News(44) ChemMonthly(3) Chemunicate(13) ChemVsCOVID(8) Christmas Chemistry(13) Cleaning Chemistry(2) Climate Crisis(1) Cocktail Chemistry(1) Colourful Chemistry(21) Coronavirus(17) Cosmetic Chemistry(11) Crime Scene Chemistry(2) Elements(8) Environmental Chemistry(7) Everyday Compounds(10) Food Chemistry(71) General Chemistry(28) Geochemistry(1)...

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Periodic Table – Royal Society of Chemistry

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Periodic Table – Royal Society of Chemistry

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The Royal Society of Chemistry's interactive periodic table features history, alchemy, podcasts, videos, and data trends across the periodic table. Click the tabs at the top to explore each section. Use the buttons above to change your view of the periodic table and view Murray Robertson's stunning Visual Elements artwork. Click each element to read detailed information.

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Periodic Table - Royal Society of Chemistry

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Interactive periodic table with element scarcity (SRI), discovery dates, melting and boiling points, group, block and period information.

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Best trick for learning the seven crystal systems | Lucky Sci

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Best trick for learning the seven crystal systems | Lucky Sci

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You can find various websites discussing the crystal systems (see my short list below), but in all honesty, the best way to mastering these systems is to deal with them in 3D.

Print out these sheets and build your own unit cells (the building blocks of a crystal) to get a 3D, tactile representation of how the systems work. Write down the relevant information (such as the name and the angle and length relationships) on each crystal. Rotate them to get an understanding of their symmetry.

To increase durability, I pasted my print-outs onto cereal boxes and then cut them out and folded them, using clear packing tape to keep the sides together (see my photo to the right).
Download the Unit Cell Models template. →
Further resources

VIDEO LECTURES: Dr. Haywick of the University of Southern Alabama has shared lectures from his crystallography and mineralogy course on YouTube (27 videos, ~0.5-1 hr each).

As always, Wikipedia is a good place to start.

The University of Liverpool has a flash animation that visually shows how the crystal systems relate to each other. Their pages feature simple, easy-to-understand paragraphs . Click "Next" and "Previous" to navigate through their topics.

If you're looking to see which minerals fall into which system, check out CrystalAge.

AllAboutGemstones has good images of actual minerals crystallizing into system shapes (used above).

Boomeria also has photos of which minerals fall into, in addition to visual slides on crystallography.

About Cortney

Hydrogeologist. A.B., M.S., earth science.

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Best trick for learning the seven crystal systems

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You can find various websites discussing the crystal systems (see my short list below), but in all honesty, the best way to mastering these systems is to deal with them in 3D. Print out these sheets and build your own unit cells (the building blocks of a crystal) to get a 3D, tactile representation of how the systems work.

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8 Chemistry Trends Across The Periodic Table Explained

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8 Chemistry Trends Across The Periodic Table Explained

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8 Chemistry Trends Across The Periodic Table Explained

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"8 Chemistry Trends Across The Periodic Table Explained" is published by Ernest Wolfe in countdown.education

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The Best 55 Online Periodic Tables - Triple Point

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The Best 55 Online Periodic Tables - Triple Point

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Since its beginning, Triple Point has a category devoted to Periodic Tables where I write about the best periodic tables on the Internet. The idea of building a ranking like this begun before the hiatus this blog has suffered. I started collecting URLs of some interesting periodic tables and found myself with a huge list of addresses. My plan was to present a top 10 or a top 20 so I started cutting. My selection was based on factors like content, design, originality and usefulness. At the end I've got a list of not 10, neither 20 but 55 great online periodic tables!
I've selected periodic tables written only in English or Portuguese, so I intentionally left out many periodic tables written in Spanish, German, Chinese or Japanese, for instance. However many ranked periodic tables have versions in several languages.
This is not a final choice. This post will stay permanently open and I expect to update it very often with more high quality periodic tables. More, I would like to hear your suggestions. If you use or know periodic tables that you think should integrate this ranking write to me or leave a comment. Thanks.
So, let's go to the ranking of the best periodic tables:

1. WebElements Periodic Table

2. Visual Elements Periodic Table

3. Merck Interactive Periodic Table of the Elements

4. Periodic Table Live!

5. EnvironmentalChemistry Periodic Table of Elements

6. The Wooden Periodic Table Table

7. It's Elemental - The Periodic Table of Elements

8. Animated Periodic Table

9. Interactive Periodic Table

10. NIST Elemental Data Index

11. Elementymology & Elements Multidict

12. Radiochemistry Society Periodic Table of the Elements

13. Wikipedia Periodic Table

14. Chemical Elements Interactive Periodic Table of the Elements

15. Los Alamos National Laboratory's Periodic Table

16. Genesis Education: Modeling the Periodic Table Interactive Simulation

17. Eni Generalic Periodic Table of the Elements

18. Mokeur's Periodic Table

19. APSIDIUM Extended Periodic Table

20. Integral Scientist Modern Standard Periodic Table

21. Chemi Cool Periodic Table

22. Visual Entities Periodic Table Applet

23. ACS Periodic Table

24. Kostas Tsigaridis Periodic Table of Elements

25. CRC Periodic Table Online

26. Michael Dayah's Periodic Table of Elements

27. Corrosion Source Periodic Table of Elements

28. Jalenack's AJAX Periodic Table of the Elements

29. David's Whizzy Periodic Table

30. IUPAC Periodic Table

31. WebQC Periodic Table of Chemical Elements

32. Rembar Periodic Table of the Elements

1. Periodic Table of Elements in the Ocean

2. Periodic Table of the Elements with Biological Roles

3. Minerals Composition Periodic Table

4. Periodic Table of the Isotopes

5. Nuclear Periodic Table

6. Cosmochemical Periodic Table of the Elements in the Solar System

7. Enhanced NMR Periodic Table

8. Elemental Spectra

9. X-Ray Periodic Table

10. Periodic Table of the Fermi Surfaces of Elemental Solids

In Portuguese

1. Merck - Tabela Periódica Interactiva

2. SoftCiências: Tabela Periódica v2.5

3. Wikipedia: Tabela Periódica

4. Enciclopedia Universal de Física e Química: Tabela Periódica

1. Periodic Table of ComicBooks

2. Poetic Table of Elements

3. Sci Fiction: Periodic Table

4. Dartmouth College Periodic Puzzle

5. "The Elements" song by Tom Lehrer

1. Idiotic Table of the Elements - Uncyclopedia

2. Table of Condiments That Periodically Go Bad

3. Periodic Table of the Operators

4. The SU Periodic Table - A Collaborative Photo Project

Further Reading

1. Dmitriy Mendeleev Online

2. C&EN It's Elemental: The Periodic Table

3. Periodic Table Data Mapping

4. Origin of the Elements and Formation of the Solar System

5. Printable Periodic Tables

6. The Most Beautiful Periodic Table Displays in the World

This entry was posted in Periodic Tables and tagged Periodic Tables, Rankings on by .

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The Best 55 Online Periodic Tables - Triple Point

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Since its beginning, Triple Point has a category devoted to Periodic Tables where I write about the best periodic tables on the Internet. The idea of building a ranking like this begun before the hiatus this blog has suffered. I started collecting URLs of some interesting periodic tables and found myself with a huge list of addresses.

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The Wooden Periodic Table Table by Theodore Gray

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The Flavor Rundown: Natural vs. Artificial Flavors - Science in the News

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The Flavor Rundown: Natural vs. Artificial Flavors - Science in the News

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by C. Rose Kennedy
figures by Kaitlyn Choi

What's in a Flavor?

The word "flavor" pervades our daily vocabulary, evoking associations of rich or vivid experiences beyond the experience of eating. Even in the literal context, theFlavor Extract Manufacturers Association (FEMA)describes flavor as "the entire range of sensations that we perceive when we eat a food or drink a beverage. Flavor encompasses a substance's taste, smell, and any physical traits we perceive" [1]. While foods do intrinsically contain flavoring substances, 90% of Americans' grocery purchases also contain added flavors [2]. These flavors are used to amplify or modulate the sensory experience associated with existing qualities of a product. Furthermore, they may also be used to make healthy yet bland options (like those lacking an excess of sugar or trans-fats) more appealing. For example, flavor agents may make reduced-fat foods seem rich and creamy, or add salty zest to low-sodium products.It's obvious that flavors have immense power to influence our gustatory experiences, but what are they and where do they come from?

All flavors, including those intrinsically present in food, as well as natural and artificial flavor additives, are small chemical compounds or mixtures of compounds (Figure 1). While chemicals often evoke negative associations, it's important to remember that all of the components of our food, our bodies, and the world around us are actually chemicals. Even things like water (dihydrogen monoxide), table sugar (sucrose, or alpha-D-glucopyranosyl-(1à2)-beta-D-fructofuranoside), and baking soda (sodium bicarbonate) are chemical compounds. In fact, the chemical properties and structures of flavoring substances are exactly what enable them to react with each other during cooking (think of that distinctive grilled flavor) bind with the taste receptors in our mouths.

The FDA broadly defines natural flavors to include any flavor isolated from natural sources like plant material (fruits, roots, bark, herbs, etc.) or animal products (meat, dairy, etc.) [3]. Artificial flavors are any flavors that are not defined as natural, even if they have the exact same chemical composition as flavors isolated directly from nature [1]. This distinction between the origins of flavors has no bearing on how safe, healthy, or delicious they are. In fact, flavor agents produced in a controlled laboratory setting undergo rigorous quality control at every stage, and do not require a lengthy, labor- and resource-intensive extraction process or acquisition of naturally rare or difficult-to-cultivate materials. As such, many nature-identical artificial flavors are actually available in higher purity than their natural congeners and may be obtained with less damage to the environment [4].

These artificial flavors are prepared by an elite group of highly trained professionals known as flavorists or flavor chemists, who must proceed through a rigorous seven-year apprenticeship (following university education) before they can become certified by the Society of Flavor Chemists [5, 6]. It is estimated that there are only roughly 500 certified flavorists worldwide [2]. Flavorists prepare mixtures of flavors to meet consumer flavor preferences, all while following a stringent set of safety and efficiency guidelines. Furthermore, because they are considered ingredient manufacturers flavorists and flavor production companies must comply with all the same FDA and USDA rules developed for food production [5].

To aid this process, a panel of scientific and medical experts (representing fields including chemistry, toxicology, pharmacology, medicine, pathology, and statistics) serving the Flavor Extract Manufacturers Association (FEMA) has compiled a list of thoroughly vetted flavor compounds that are "generally recognized as safe (GRAS)" [7]. The FEMA Expert Panel communicates their findings and all scientific data with the FDA, with international scientific and regulatory bodies, and in the scientific literature [8, 9]. Flavor companies are not required to disclose application of flavor ingredients that have already passed this rigorous review, but any novel flavor substances that have not yet made it onto the list require rigorous testing and approval to demonstrate safety before they may be incorporated into consumer products.

Let's consider a few cases of flavor chemistry in action!

Vanillin Dreams

Vanilla is the most popular flavor worldwide. Not only is it used in favorites like ice cream, candies, cakes, and cookies, but vanilla also enhances perception of sweetness and other flavors (like those in chocolate, coffee, fruit, and nuts) [10].

Natural vanilla extract is obtained by steeping vanilla beans in alcohol to afford a solution of vanillin and other minor components that may be used in cooking and baking. While as many as 250 taste and aroma components have been detected in vanilla extract, most of these are destroyed upon exposure to elevated temperature, causing the complexity of the vanilla flavor to diminish upon baking. Furthermore, vanilla beans can only be obtained from hand-pollinated flowering orchids in a handful of tropical areas, making them precious commodities, especially given the vast demand for vanilla (over 16,000 metric tons annually) worldwide [19]. To meet this demand, flavor companies like International Flavors and Fragrances, Inc. and Givaudan have entire production lines devoted to development of high-quality substitutes for natural vanilla extract [11], [12].

One of these substitutes is castoreum extract. Castoreum is a secretion from the anal glands and castor sacs of beavers, which use it to mark their territorial claims. Castoreum extract possesses a warm, sweet odor and may be used as a stand-in for vanilla extract in many dairy products and baked goods [13]. Following rigorous evaluation, castoreum and its extracts have earned a place on the GRAS List; however, worldwide consumption is relatively low (only about 300 pounds annually). It is interesting to note, though, that because castoreum is extracted from an animal source, it is considered a natural flavor, not an artificial flavor.

The bulk of vanilla substitutes are actually nature-identical vanillin and vanillin derivatives synthesized on multi-ton scale from guaiacol or lignin extracts, which can be isolated from wood pulp (Figure 2) [14], [15]. In addition to providing an inexpensive source of vanillin-in higher purity than one could obtain from natural vanilla extract-this synthesis enables production of vanillin derivatives possessing desirable qualities, like increased flavor potency and thermal stability. For example adding one extra carbon atom to vanillin affords ethyl vanillin, which is 2-4 times more flavorful than vanillin itself. Due to this desirable property and its long-standing status on the GRAS list, ethyl vanillin has been used in some vanilla flavoring since the 1930s. [16] Perhaps it should come as no surprise, then, that in blind taste-tests, tasters preferred the artificial vanilla flavoring (including industrially produced vanillin and its analogues) in treats like cookies that must be baked at the high temperatures that cause many of the minor components of natural vanilla extract to decompose [10].

Butter Me Up

The rich, smooth flavor of butter is another consumer favorite, adding body and depth to cooking sprays, sauces, baked goods, and (of course) popcorn. This flavor arises from the production of diacetyl and acetoin as byproducts of sugar fermentation in the production of cultured dairy products like cultured butter, buttermilk, and sour cream [17].

While small quantities of these compounds can be isolated from these consumer-based dairy products, the very low efficiency of the extraction limits its practicality. Instead, these flavor additives are generally produced through chemical synthesis or industrial fermentation on specialized culture, which is optimized for flavor production, but is not the sort of media people generally like to eat (Figure 3) [18]. When produced through this culturing technique, diacetyl and acetoin are listed as "natural butter flavoring," but when they are produced through controlled laboratory synthesis, the very same components are listed as "artificial butter flavoring" [19].

You may have heard reports about "popcorn worker's lung," in which a handful of cases of lung disease have been linked to inhalation of very high levels of diacetyl in some microwave popcorn production facilities [20]. However, both diacetyl and acetoin are long-standing members of the GRAS list. It is essential to remember that a high dose of anything can be toxic! For example, there have been numerous cases of deaths related to overdosing on water (not drowning, actually just drinking far too much) [21], [22]. The FDA and OSHA have investigated concerns regarding aerosolized diacetyl carefully and have developed new standards to limit exposure to airborne particles in occupational settings [23]. Additionally, their reports reiterate that the levels to which general consumers are exposed is far below the risk threshold. Furthermore, ingesting flavor agents like diacetyl routes these substances to the stomach (rather than the lungs), which is perfectly equipped to process these molecules. So go ahead, have your butter (flavor) and eat it too!

A Flavor Like You've Never Dreamed

As a few of our classic flavor favorites illustrate, flavor chemistry is both an art and a science dedicated to safely producing robust and resource-efficient natural and artificial flavors for your enjoyment. Perhaps the most exciting aspect, however, is the opportunity to combine known flavors in novel ways to explore flavors beyond what we've ever experienced.Flavorists seek to identify and fill "white spaces," which are combinations of flavor qualities that consumer may enjoy but are unrepresented in products on the market. So next time you try an out-of-this-world treat like Juicy Fruit™ gum, a novel jelly bean, or your favorite sports drink, remember the labor of love that went into its development [23]. For in the memorable words of Willy Wonka: "Invention, my dear friends, is 93% perspiration, 6% electricity, 4% evaporation, and 2% butterscotch ripple."
C. Rose Kennedy is a Ph.D. candidate in the Department of Chemistry and Chemical Biology at Harvard University.
References

[1] Flavor Facts. Flavor Extract Manufacturers Association (FEMA) http://www.flavorfacts.org (accessed August 23, 2015)

[2] "The Tastemakers" La Gorce, T. New Jersey Monthly. January 17, 2011. http://njmonthly.com/articles/eat-drink/the-tastemakers/ (accessed August 23, 2015)

[3] "Section 101.22 Foods; labeling of spices, flavorings, colorings and chemical preservatives." Code of Federal Regulations. Title 21 - Food and Drugs. Food And Drug Administration, Department Of Health And Human Services. April 1, 2010. http://www.gpo.gov/fdsys/pkg/CFR-2010-title21-vol2/xml/CFR-2010-title21-vol2-sec101-22.xml (accessed August 23, 2015)

[4] "What is the difference between artificial and natural flavors?" Reineccius, G. Scientific American. July 29, 2002. http://www.scientificamerican.com/article/what-is-the-difference-be-2002-07-29/ (accessed August 23, 2015)

[5] The Society of Flavor Chemists. http://flavorchemists.com/ (accessed August 23, 2015)

[6] "You're a what? Flavorist" Green, K. Occupational Outlook Quarterly. Winter 2004-2005. US Bureau of Labor Statistics http://www.bls.gov/careeroutlook/2004/winter/yawhat.pdf

[7] "The Taste Makers" Khatchadourian, R. The New Yorker. November 23, 2009. http://www.newyorker.com/magazine/2009/11/23/the-taste-makers (accessed August 23, 2015)

[8] "Flavor Safety: Myth vs. Fact" Mat. Flavor Facts. Flavor Extract Manufacturers Association (FEMA) June 25, 2015. http://www.flavorfacts.org/flavor-safety-myth-vs-fact/ (accessed August 23, 2015)

[9] "How U.S. FDA's GRAS Notification Program Works" Gaynor, P. Food Safety Magazine, December 2005/January 2006. http://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS/ucm083022.htm#authors (accessed August 23, 2015)

[10] "Vanilla Extract" Cook's Illustrated. March 1, 2009. http://www.cooksillustrated.com/taste_tests/455-vanilla-extract (accessed August 23, 2015)

[11] Always Vanilla. International Flavors and Fragrances, Inc. http://alwaysvanilla.com/ (accessed August 23, 2015)

[12] Anything but Plain Vanilla. Givaudan TasteEssentials Vanilla. https://www.givaudan.com/flavours/world-flavours/tasteessentials/vanilla (accessed August 23, 2015)

[13] "Castoreum" Burdock, G. A. Fenaroli's Handbook of Flavor Ingredients. CRC Press, 2005. 276-278

[14] "Vanillin: Synthetic Flavoring from Spent Sulfite Liquor." Hocking, M. B. Journal of Chemical Education, 1997, 74, 1055. DOI: 10.1021/ed074p1055

[15] "Vanillin" Vidal, J.-P. Kirk-Othmer Encyclopedia of Chemical Technology, 2006, DOI: 10.1002/0471238961.2201140905191615.a01.pub2

[16] "Ethyl Vanillin" Burdock, G. A. Fenaroli's Handbook of Flavor Ingredients. CRC Press, 2005. 639-640.

[17] Pavia et al. Introduction to Organic Laboratory Techniques (4th ed.). ISBN 978-0-495-28069-9.

[18] "Production of Diacetyl and Acetoin by Lactic Acid Bacteria" Oberman, H., Piątkiewicz, A.; Libudzisz, Z. Nahrung, 1982, 26, 615. DOI: 10.1002/food.19820260706

[19] "Biotechnological Production of Flavours and Fragrances" Krings, C.; Berger, R. G. Applied Microbiol Biotechnology. 1998, 49, 8.a

[20] "Beware Diacetyl: The Next Legal Quagmire" Fama, R. Food Safety Magazine. October/November 2007. http://www.foodsafetymagazine.com/magazine-archive1/octobernovember-2007/beware-diacetyl-the-next-legal-quagmire/ (accessed August 23, 2015)

[21] "Hyponatremia" Adrogué, H. J.; Madias, N. E. New England Journal of Medicine 2000, 342, 1581. DOI: 10.1056/NEJM200005253422107

[22] "Death from hyponatremia as a result of acute water intoxication in an Army basic trainee." Garigan, T. P.; Ristedt, D. E. Military Medicine,1999, 164, 234.

[23] "NIOSH Alert: Preventing Lung Disease in Workers Who Use or Make Flavorings," DHHS (NIOSH) Publication No. 2004-110. http://www.cdc.gov/niosh/docs/2004-110/ (accessed August 23, 2015)

[24] "Sweet Memories: How Jelly Belly Invents Flavors" Greenwood, V. The Atlantic. August 17, 2010. http://www.theatlantic.com/health/archive/2010/08/sweet-memories-how-jelly-belly-invents-flavors/61477/ (accessed August 23, 2015)

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The Flavor Rundown: Natural vs. Artificial Flavors - Science in the News

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by C. Rose Kennedy figures by Kaitlyn Choi What's in a Flavor? The word "flavor" pervades our daily vocabulary, evoking associations of rich or vivid experiences beyond the experience of eating. Even in the literal context, the Flavor Extract Manufacturers Association (FEMA) describes flavor as "the entire range of sensations that we perceive when we eat a food or drink a beverage.

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BBC World Service - Elements - Episode guide

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BBC World Service - Elements - Episode guide

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BBC World Service - Elements - Episode guide

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Chemical elements: where do we get them and how do they fit into our economy?

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The Photographic Periodic Table of the Elements

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The Photographic Periodic Table of the Elements

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The Photographic Periodic Table of the Elements

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The definitive online periodic table reference site including technical data, and photographs and descriptions of thousands of samples of the chemical elements.

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Beauty of Science (BOS) is an educational brand that produces inspiring content for science education and outreach.

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Online version of the 'IUPAC Compendium of Chemical Terminology' also known as the 'IUPAC Gold Book'

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Periodic Table of Elements - IUPAC | International Union of Pure and Applied Chemistry

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Periodic Table of Elements - IUPAC | International Union of Pure and Applied Chemistry

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IUPAC | International Union of Pure and Applied Chemistry

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The latest release of the Periodic Table (dated 28 November 2016) includes the recently added elements 113, 115, 117, and 118 with their names and symbols ( see related News), the standard atomic weights 2013 (abridged to five significant digits) and the conventional atomic weights as published in PAC Vol. 88, No.3, pp. 265-291 ( http://dx.doi.org/10.1515/pac-2015-0305), and for ytterbium, the standard atomic weight updated following the 2015 review ( see related News). An interval in square brackets provides the lower and upper bounds of the standard atomic weight for that element. For users needing an atomic-weight value for an unspecified sample with disregard to the uncertainty, the conventional values are provided. No values are listed for elements which lack isotopes with a characteristic isotopic abundance in natural terrestrial samples.

See PAC for more details or visit Commission II.1 @ ciaaw.org
Visit www.isotopesmatter.com for an interactive version of the Periodic Table of the Elements and Isotopes.

Download the printable (PDF) version (letter size or A4) or A3 (PDF) version

By virtue of its work in relation with the chemical elements, IUPAC can dispense a periodic table that is up-to-date. IUPAC involvement covers various aspects of the table and data that it unveils, and several reports and recommendations, some quite recent, attest of that input.

In particular, IUPAC is directly involved in the following:

1. establishing the criteria for a new element discovery

2. defining the structure of a temporary name and symbol

3. assessing claims resulting in the validation and assignation of an element discovery

4. coordinating the naming of a new element, involving the research laboratory and allowing for public comments

5. setting up precise rules for how to name a new element

6. defining Group 1-18 and collective names

7. determining which elements belong to Group 3

8. regularly reviewing standard atomic weights

The table is yours to use. Details about the latest release are provided above. Details below provide multiple references to IUPAC journal in Pure and Applied Chemistry ( PAC) and magazine Chemistry International ( CI).

Criteria for a new element discovery

Assessing if an element has been "discovered" is not a simple task. While reviewing the discovery profiles of the transfermium elements in the early 90s', IUPAC and IUPAP set up to establish a series of criteria that must be satisfied for the discovery of an element to be recognized. See details in PAC 1991, Vol. 63, No. 6, pp. 879-886 ( http://dx.doi.org/10.1351/pac199163060879) and PAC 1993, Vol. 65, No. 8, pp. 1757-1814 ( http://dx.doi.org/10.1351/pac199365081757)

While an element can have been claimed, before the claim has been validated and before the element is formally named, the element has a temporary name and symbol. The pertinent recommendations setting-up that systematic nomenclature was published in 1978; see 1979, Vol. 51, No. 2, pp. 381-384; http://dx.doi.org/10.1351/pac197951020381

In result, that is how, in March 2016, element 113 was called ununtrium or with the symbol Uut.

The story behind the three-letter symbols is recounted in a feature prepared by Lars Öhrström and Norman Holden and published in Chem Int 2016, Vol. 38, No. 2, pp. 4-8; http://dx.doi.org/10.1515/ci-2016-0204

Validation and assignation of an element discovery

Claims for the discoveries of new elements appear time to time in the scientific literature. IUPAC, along with IUPAP, is involved in assessing these claims. In result, IUPAC technical reports are released that review each pertaining references and recognize the laboratory(ies) whose claims fulfill the agreed criteria.

In 2016, two such reports have been released that cover elements 113, 115, 117, and element 118; See PAC 2016, Vol. 88, No. 1-2, pp. 139-153; http://dx.doi.org/10.1515/pac-2015-0502 and PAC 2016, Vol. 88, No. 1-2, pp. 155-160; http://dx.doi.org/10.1515/pac-2015-0501

When the discovery of a new element has been validated and the priority for its discovery has been assigned, the naming process can begin. The Laboratory to which the discovery has been assigned is invited to propose a name and symbol. IUPAC will then review the proposal, and if agreed, after an additional 5-month public review, will formalize the name. The most recent example of such recommendations were published in 2012 and for the names and symbols of the elements 114 and 116; See PAC 2012, Vol. 84, No. 7, pp. 1669-1672; http://dx.doi.org/10.1351/PAC-REC-11-12-03

A short review of the current procedures is published in a recent feature by John Corish; See CI 2016, Vol. 38, No. 2, pp. 9-11; http://dx.doi.org/10.1515/ci-2016-0205

On 8 June 2016, IUPAC released the provisional names for the latest 4 elements 113, 115, 117, and 118 - see release and on 28 November 2016, IUPAC announced the approved names and symbols - see release.

For a reflection on the 2016 experience of the naming of elements, see Chem Int Apr 2017, pp. 30-21, by Jan Reedijk; https://doi.org/10.1515/ci-2017-0222

Here again, IUPAC has a set of guidelines that outline what sort of name an element can bear. Both the root and the ending must be consistent with the agreed recommendations. The detailed recommendations were published in 2002 and a revision published in 2016 to better accommodate element in group 17 and 18. See PAC 2002, Vol. 74, No. 5, pp. 787-791; http://dx.doi.org/10.1351/pac200274050787 and PAC 2016, Vol. 88, No. 4, pp. 401-405 http://dx.doi.org/10.1515/pac-2015-0802 (or http://www.iupac.org/project/2015-031-1-200)

Since 1988, IUPAC recommended that the groups ( i.e. columns) be simply numbered from 1 to 18. ( PAC 1988, Vol. 60, No. 3, pp 431-436; http://dx.doi.org/10.1351/pac198860030431)

Lanthanoids and actinoids are collective names also recommended by IUPAC. Lanthanoids (La to Lu) is preferred over lanthanide, and although lanthanoid means 'like lanthanum' and so should not include lanthanum, lanthanum has become included by common usage, however. Actinoids include Ac to Lr.

The question of precisely which elements should be placed in group 3 has been debated from time to time. An IUPAC project has been recently initiated to resolve the question. Will group 3 consist of Sc, Y, Lu, and Lr or, will it consist of Sc, Y, La and Ac?

Stay tune and see http://www.iupac.org/project/2015-039-2-200 and CI 2016, Vol. 38, No. 2, pp. 22-23; http://dx.doi.org/10.1515/ci-2016-0213

One of the tasks of the Commission on the Isotopic Abundances and Atomic Weights (CIAAW) is to periodically review atomic-weight determinations. The most recent report "Atomic weights of the elements 2013" has been published in PAC in March 2016 ( PAC 2016, Vol. 88, No. 3, pp. 265-291; http://dx.doi.org/10.1515/pac-2015-0305). In recent years, such systematic review has been released every two years.

The Commission was established in 1899 (yes, in eighteen ninety nine) and is now operating under the Inorganic Chemistry Division of IUPAC. (see www.ciaaw.org ) It also reviews regularly Isotopic compositions of the elements; the latest compilation is also published in PAC in March 2016 ( PAC 2016, Vol. 88, No. 3, pp. 293-306; http://dx.doi.org/10.1515/pac-2015-0503)

Yours to use
While IUPAC has no recommendation for a specific form of the periodic table, i.e. 18-column or 32-column format, the version here presented is in the conventional long form and is yours to use.

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IUPAC | International Union of Pure and Applied Chemistry Periodic Table of Elements

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The latest release of the Periodic Table (dated 28 November 2016) includes the recently added elements 113, 115, 117, and 118 with their names and symbols ( see related News ), the standard atomic weights 2013 (abridged to five significant digits) and the conventional atomic weights as published in PAC Vol.

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The science and technology of composite materials - Curious

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The science and technology of composite materials - Curious

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The science and technology of composite materials - Curious

Javascript must be enabled for the correct page display

Essentials

Composite materials are formed by combining two or more materials with different properties, without dissolving or blending them into each other

Examples include concrete, mud bricks, and fibreglass

Most composites are made by taking one material (the matrix) and having it surround fibres or fragments of a stronger material (the reinforcement)

Engineers have many choices during the manufacturing process to determine what the properties of the resulting composite will be

Modern aviation has been the primary driver for composite materials, as it has great demand for materials that are both light and strong

What makes a material a composite

Composite materials are formed by combining two or more materials that have quite different properties. The different materials work together to give the composite unique properties, but within the composite you can easily tell the different materials apart - they do not dissolve or blend into each other.

Composites exist in nature. A piece of wood is a composite, with long fibres of cellulose (a very complex form of starch) held together by a much weaker substance called lignin. Cellulose is also found in cotton and linen, but it is the binding power of the lignin that makes a piece of timber much stronger than a bundle of cotton fibres.

It's not a new idea

Humans have been using composite materials for thousands of years. Take mud bricks for example. If you try to bend a cake of dried mud, it will break easily but it is strong if you try to squash, or compress it. A piece of straw, on the other hand, has a lot of strength when you try to stretch it but almost none when you crumple it up. When you combine mud and straw in a block, the properties of the two materials are also combined and you get a brick that is strong against both squeezing and tearing or bending. Put more technically, it has both good and good .

Another well-known composite is concrete. Here aggregate (small stones or gravel) is bound together by cement. Concrete has good strength under compression, and it can be made stronger under tension by adding metal rods, wires, mesh or cables to the composite (so creating reinforced concrete).

Composites have been made from a form of carbon called graphene combined with the metal copper, producing a material 500 times stronger than copper on its own. Similarly, a composite of graphene and nickel has a strength greater than 180 times of nickel.

More than strength

Nowadays many composites are made for functions other than simply improved strength or other mechanical properties. Many composites are tailored to be good conductors or insulators of heat or to have certain magnetic properties; properties that are very specific and specialised but also very important and useful. These composites are used in a huge range of electrical devices, including transistors, solar cells, sensors, detectors, diodes and lasers as well as to make anti-corrosive and anti-static surface coatings.

Composites made from metal oxides can also have specific electrical properties and are used to manufacture silicon chips that can be smaller and packed more densely into a computer. This improves the computer's memory capacity and speed. Oxide composites are also used to create high temperature superconducting properties that are now used in electrical cables.

Making a composite

Most composites are made up of just two materials. One material (the matrix or binder) surrounds and binds together a cluster of fibres or fragments of a much stronger material (the reinforcement). In the case of mud bricks, the two roles are taken by the mud and the straw; in concrete, by the cement and the aggregate; in a piece of wood, by the cellulose and the lignin. In fibreglass, the reinforcement is provided by fine threads or fibres of glass, often woven into a sort of cloth, and the matrix is a plastic.

Over recent decades many new composites have been developed, some with very valuable properties. By carefully choosing the reinforcement, the matrix, and the manufacturing process that brings them together, engineers can tailor the properties to meet specific requirements. They can, for example, make the composite sheet very strong in one direction by aligning the fibres that way, but weaker in another direction where strength is not so important. They can also select properties such as resistance to heat, chemicals, and weathering by choosing an appropriate matrix material.

Choosing materials for the matrix

Thermosetting plastics are liquid when prepared but harden and become rigid (ie, they cure) when they are heated. The setting process is irreversible, so that these materials do not become soft under high temperatures. These plastics also resist wear and attack by chemicals making them very durable, even when exposed to extreme environments.

Thermosoftening plastics, as the name implies, are hard at low temperatures but soften when they are heated. Although they are less commonly used than thermosetting plastics they do have some advantages, such as greater fracture toughness, long shelf life of the raw material, capacity for recycling and a cleaner, safer workplace because organic solvents are not needed for the hardening process.

Ceramics, carbon and metals are used as the matrix for some highly specialised purposes. For example, ceramics are used when the material is going to be exposed to high temperatures (such as heat exchangers) and carbon is used for products that are exposed to friction and wear (such as bearings and gears).

Choosing materials for the reinforcement

Although glass fibres are by far the most common reinforcement, many advanced composites now use fine fibres of pure carbon. There are two main types of carbon that can be used - graphite and carbon nanotubes. These are both pure carbon, but the carbon atoms are arranged in different crystal configurations. Graphite is a very soft substance (used in 'lead'pencils) and is made of sheets of carbon atoms arranged in hexagons. The bonds holding the hexagons together are very strong, but the bonds holding the sheets of hexagons together are quite weak, which is what makes graphite soft. Carbon nanotubes are made by taking a single sheet of graphite (known as graphene) and rolling it into a tube. This produces an extremely strong structure. It's also possible to have tubes made of multiple cylinders - tubes within tubes.

Carbon fibre composites are light and much stronger than glass fibres, but are also more expensive. Of the two, graphite fibres are cheaper and easier to produce than carbon nanotubes. They are used in aircraft structures and in high performance sporting equipment like golf clubs, tennis rackets and rowing boats, and are increasingly being used instead of metals to repair or replace damaged bones.

Even stronger (and more costly) than carbon fibres are threads of boron. Nanotubes of boron nitride have the additional advantage of being much more resistant to heat than carbon fibres. They also possess piezoelectric qualities, which means they can generate electricity when physical pressure is applied to them, such as twisting or stretching.

Polymers can also be used as the reinforcement material in composites. For example, Kevlar, originally developed to replace steel in radial tyres but best known for its use in bullet-proof vests and helmets, is a polymer fibre that is immensely strong and adds toughness to a composite. It is used as the reinforcement in composite products that require lightweight and reliable construction (eg, structural body parts of an aircraft). Even stronger than Kevlar is a substance made from a combination of graphene and carbon nanotubes.

Choosing the manufacturing process

Making an object from a composite material usually involves some form of mould. The reinforcing material is first placed in the mould and then semi-liquid matrix material is sprayed or pumped in to form the object. Pressure may be applied to force out any air bubbles, and the mould is then heated to make the matrix set solid.

In many thin structures with complex shapes, such as curved panels, the composite structure is built up by applying sheets of woven fibre reinforcement, saturated with the plastic matrix material, over an appropriately shaped base mould. When the panel has been built to an appropriate thickness, the matrix material is then cured.

Sandwich composites

Many new types of composites are not made by the matrix and reinforcement method but by laying down multiple layers of material. The structure of many composites (such as those used in the wing and body panels of aircraft), consists of a honeycomb of plastic sandwiched between two skins of carbon-fibre reinforced composite material.

These sandwich composites combine high strength, and particularly bending stiffness, with low weight. Other methods involve simply laying down several alternating layers of different substances (for example, graphene and metal) to make the composite.

Why use composites?

The greatest advantage of composite materials is strength and stiffness combined with lightness. By choosing an appropriate combination of reinforcement and matrix material, manufacturers can produce properties that exactly fit the requirements for a particular structure for a particular purpose.

Modern aviation, both military and civil, is a prime example. It would be much less efficient without composites. In fact, the demands made by that industry for materials that are both light and strong has been the main force driving the development of composites. It is common now to find wing and tail sections, propellers and rotor blades made from advanced composites, along with much of the internal structure and fittings. The airframes of some smaller aircraft are made entirely from composites, as are the wing, tail and body panels of large commercial aircraft.

In thinking about planes, it is worth remembering that composites are less likely than metals (such as aluminium) to break up completely under stress. A small crack in a piece of metal can spread very rapidly with very serious consequences (especially in the case of aircraft). The fibres in a composite act to block the widening of any small crack and to share the stress around.

The right composites also stand up well to heat and corrosion. This makes them ideal for use in products that are exposed to extreme environments such as boats, chemical-handling equipment and spacecraft. In general, composite materials are very durable.

Another advantage of composite materials is that they provide design flexibility. Composites can be moulded into complex shapes - a great asset when producing something like a surfboard or a boat hull.

Additionally, a lot of work is currently being directed towards development of composite materials made from waste products, such as agricultural waste, building materials or plastic drink containers.

The downside of composites is usually the cost. Although manufacturing processes are often more efficient when composites are used, the raw materials are expensive. Composites will never totally replace traditional materials like steel, but in many cases they are just what we need. And no doubt new uses will be found as the technology evolves. We haven't yet seen all that composites can do.

Nanoscience: thinking big, working small

From sunlight to electricity

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The science and technology of composite materials

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The science and technology of composite materials - Curious Javascript must be enabled for the correct page display Essentials Composite materials are formed by combining two or more materials with different properties, without dissolving or blending them into each other Examples include concrete, mud bricks, and fibreglass Most composites are

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Blown plate was made by hand-grinding broad sheet glass. As the process was labour-intensive, and expensive, blown plate was mainly used for carriages and mirrors rather than in windows for buildings. Other methods for making hand-blown glass included: broad sheet, crown glass, polished plate and cylinder blown sheet.

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Teacher resources and professional development across the curriculum

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Worldwide, less than 10 percent of the plastic we use gets recycled. Most ends up in a landfill. And much of that eventually makes its way out to sea, clogging up our oceans.

And here's the extra bad news: Global demand for plastic is projected to triple by midcentury.

Here's the problem with plastic: It's super useful, lightweight and strong, and smooth and flexible. Back when Dustin Hoffman's legendary character in the movie, The Graduate was entering the workforce a half-century ago, the career advice was simple: "Just one word: Plastics!"

But the guy giving advice to the young college graduate probably wasn't thinking of all the junk we'd still be stuck with two generations later. Plastic toys, straws, and tiny ketchup pouches - things that make life more convenient - can take hundreds of years to degrade.

Here's the other problem. Plastic isn't just plastic. There are hundreds of different kinds. Think of a flexible plastic baggie versus a water bottle versus rigid plastic for your computer keyboard. Most of us just toss it all in a blue recycling bin and say: "Should be OK."

"The industry has started calling that wish-cycling," said Susan Collins, president of the Container Recycling Institute in California. "Especially with curbside recycling that uses this single-stream process where we put all our recyclables in one bin, the expression we use a lot is that, 'You can't unscramble an egg.'"

And when recycling gets contaminated, it becomes trash, bound for the landfill. Still, even if you deliver a pristine batch of plastic bottles to the recycler, there's another hurdle.

"Plastics are inherently susceptible to some decrease in their properties when they're recycled," said Sue Selke, director of the Center for Packaging Innovation and Sustainability at Michigan State University.

There are only so many times a plastic bottle can be melted down and reused before it degrades too far in quality.

"That leads to this overabundance of plastics in our waste streams," said Brett Helms, a staff scientist at the U.S. Department of Energy's Lawrence Berkeley National Laboratory. His team is designing a new type of plastic, PDK ( polydiketoenamine), which can be used over and over.

Scientist Brett Helms at the U.S. Department of Energy's Lawrence Berkeley National Laboratory. | (Jason Margolis/Courtesy The World)

"What we've created is a plastic that can be deconstructed into its molecular building blocks," Helms said.

So, for example, a phone case could be later rebuilt into a watchband or part of a new shoe. "And the way that becomes possible is by designing plastics to degrade with essentially no difference in quality or performance from the virgin resin."

Most plastics are not like Legos. Once the pieces - or molecules in this case - are snapped together, they can't easily be taken apart.

"But for recycling, you need to go in the reverse direction," Helms said. "So, you need to take these big long chains that may have other things in them, and you have to be able to efficiently deconstruct them at the molecular level."

Acid allows this new plastic to be depolymerized - broken down into basic molecular building blocks called monomers - and Helms hopes that his new plastic encourages other innovators to rethink how plastic is designed.

The British newspaper, The Independent, asked if this could be the holy grail of plastic.

"If you think it's the holy grail, you're definitely getting prematurely excited," Selke said, adding that she still wants to learn more about this new plastic being cooked up in the labs of Berkeley.

Some commercially available plastic can already be broken down to the molecular level. (The new plastic in Berkeley could be an improvement, however, being more flexible than current plastics that can be chemically recycled.) But there is a problem with chemical recycling: It's not cheap.

"It takes more expense, more energy, usually to do that kind of recycling than to just do mechanical recycling," Selke said.

Mechanical recycling is, simply put, melting down old plastics to make new ones. It's a cheaper way to recycle, but again, you can only do that so many times.

But there's more to this plastic debate than just economics.

One recent study delivered a sobering statistic: If we fail to rethink how we're using plastics, by midcentury, when measured pound for pound, there will be more plastic in our oceans than fish.
This article originally appeared at PRI's The World.

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Worldwide, less than 10 percent of the plastic we use gets recycled. Most ends up in a landfill. And much of that eventually makes its way out to sea, clogging up our oceans. And here's the extra bad news: Global demand for plastic is projected to triple by midcentury.

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Explore this collection of videos on each element in the periodic table. Featuring Murray Robertson's Visual Elements annimated artwork and videos from the University of Nottingham's Periodic Table of Videos.

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Graphene: The Next Wonder Material? - American Chemical Society

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Graphene: The Next Wonder Material? - American Chemical Society

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Can't crush this: Beetle armor gives clues to tougher planes

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Can't crush this: Beetle armor gives clues to tougher planes

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NEW YORK (AP) - It's a beetle that can withstand bird pecks, animal stomps and even being rolled over by a Toyota Camry. Now scientists are studying what the bug's crush-resistant shell could teach them about designing stronger planes and buildings.

"This beetle is super tough," said Purdue University civil engineer Pablo Zavattieri, who was among a group of researchers that ran over the insect with a car as part of a new study.

So, how does the seemingly indestructible insect do it? The species - aptly named diabolical ironclad beetle - owes its might to an unusual armor that is layered and pieced together like a jigsaw, according to the study by Zavattieri and his colleagues published in Nature on Wednesday. And its design, they say, could help inspire more durable structures and vehicles.

To understand what gives the inch-long beetle its strength, researchers first tested how much squishing it could take. The species, which can be found in Southern California's woodlands, withstood compression of about 39,000 times its own weight.

For a 200-pound man, that would be like surviving a 7.8-million-pound crush.

Other local beetle species shattered under one-third as much pressure.

Researchers then used electron microscopes and CT scans to examine the beetle's exoskeleton and figure out what made it so strong.

As is often the case for flightless beetles, the species' elytra - a protective case that normally sheaths wings - had strengthened and toughened over time. Up close , scientists realized this cover also benefited from special, jigsaw-like bindings and a layered architecture.

When compressed, they found the structure fractured slowly instead of snapping all at once.

"When you pull them apart," Zavattieri said, "it doesn't break catastrophically. It just deforms a little bit. That's crucial for the beetle."

It could also be useful for engineers who design aircrafts and other vehicles and buildings with a variety of materials such as steel, plastic and plaster. Currently, engineers rely on pins, bolts, welding and adhesives to hold everything together. But those techniques can be prone to degrading.

In the structure of the beetle's shell, nature offers an "interesting and elegant" alternative, Zavattieri said.

Because the beetle-inspired design fractures in a gradual and predictable way, cracks could be more reliably inspected for safety, said Po-Yu Chen, an engineer at Taiwan's National Tsing Hua University not involved in the research.

The beetle study is part of an $8 million project funded by the U.S. Air Force to explore how the biology of creatures such as mantis shrimp and bighorn sheep could help develop impact-resistant materials.

"We're trying to go beyond what nature has done," said study co-author David Kisailus, a materials scientist and engineer at the University of California, Irvine.

The research is the latest effort to borrow from the natural world to solve human problems, said Brown University evolutionary biologist Colin Donihue, who was not involved in the study. Velcro, for example, was inspired by the hook-like structure of plant burrs. Artificial adhesives took a page from super-clingy gecko feet.

Donihue said endless other traits found in nature could offer insight: "These are adaptations that have evolved over millennia."

___

Follow Marion Renault on Twitter: @MarionRenault

___

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.

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Can't crush this: Beetle armor gives clues to tougher planes

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NEW YORK (AP) - It's a beetle that can withstand bird pecks, animal stomps and even being rolled over by a Toyota Camry. Now scientists are studying what the bug's crush-resistant shell could teach them about designing stronger planes and buildings.

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The Periodic Table of Endangered Elements - American Chemical Society

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The Periodic Table of Endangered Elements - American Chemical Society

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What are Endangered & Critical Elements?

Of the 118 elements that make up everything-from the compounds in a chemist's arsenal to consumer products on the shelf-44 will face supply limitations in the coming years. These critical elements include rare earth elements, precious metals, and even some that are essential to life, like phosphorus.

Download a high resolution image of the Periodic Table's Endangered Elements [PDF]

How Do Endangered & Critical Elements Relate to Green Chemistry?

Endangered elements in the chemical enterprise face critical supply risks, making sustainable management of their extraction, use, reuse and dispersion essential. In addition to the environmental cost of extracting and processing endangered elements, there is, for some of these materials, an additional human cost of conflict minerals mined to finance armed disputes. Research into more abundant alternatives, more efficient uses, recycling and recovery will help mitigate risks and move industry towards sustainable supply chains.

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The Periodic Table of Endangered Elements - American Chemical Society

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Of the 118 elements that make up everything-from the compounds in a chemist's arsenal to consumer products on the shelf-44 will face supply limitations in the coming years. These critical elements include rare earth elements, precious metals, and even some that are essential to life, like phosphorus.

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Don't Panic about Rare Earth Elements - Scientific American

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Don't Panic about Rare Earth Elements - Scientific American

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As trade tensions rise between the U.S. and China, rare earth minerals are once again in the political spotlight. Today Chinese mines and processing facilities provide most of the world's supply, and Chinese leader Xi Jinping has hinted about using this as political leverage in trade negotiations with U.S. President Donald Trump's administration. But in the long run, many experts say the global market involving these materials would likely survive even if China completely stopped exporting them.

The 17 rare earth elements, which cluster near the bottom of the periodic table, play a vital role in several industries: consumer electronics including Apple AirPods and iPhones, green technologies such as General Electric wind turbines and Tesla electric cars, medical tools including Philips Healthcare scanners, and military hardware such as F-35 jet fighters. The U.S. government lists them among minerals deemed critical to the country's economic and national security, and the Trump administration notably exempted rare earth elements from tariffs it imposed on $300 billion worth of Chinese goods. On the other side of the trade conflict, Xi recently made a politically symbolic visit to one of China's main rare earth mining and processing facilities, and China used tariffs of its own to target a U.S. rare earth mine in California. Such political posturing on both sides, however, may overemphasize the world's reliance on China's supply of rare earth elements.

"Politicians get too alarmed or too wrapped up in the idea of political manipulation of markets," says Eugene Gholz, an associate professor of political science at the University of Notre Dame. "There's a big difference between individual companies making or losing money, and the large-scale ability to get political influence in this particular market."

The "rare" in the name of this group of elements is actually somewhat misleading; the U.S. Geological Survey describes them as "relatively abundant in the Earth's crust." But extraction is complicated by the fact that in the ground, such elements are jumbled together with many other minerals in different concentrations. The raw ores go through a first round of processing to produce concentrates, which head to another facility where high-purity rare earth elements are isolated. Such facilities perform complex chemical processes that most commonly involve a procedure called solvent extraction, in which the dissolved materials go through hundreds of liquid-containing chambers that separate individual elements or compounds-steps that may be repeated hundreds or even thousands of times. Once purified, they can be processed into oxides, phosphors, metals, alloys and magnets that take advantage of these elements' unique magnetic, luminescent or electrochemical properties. The strong and lightweight nature of rare earth magnets, metals and alloys have made them especially valuable in high-tech products.

China currently has most of the world's separation facilities-but if it ever were to stop exporting the purified materials, other options exist. In the short term, U.S. companies that rely on these minerals would likely have inventory stockpiles for brief supply shortages, Gholz says, who served from 2010 to 2012 as senior advisor to the Pentagon's Deputy Assistant Secretary of Defense for Manufacturing and Industrial Base Policy. To stretch those stockpiles out, the overall market could prioritize rare earth elements for crucial applications such as military and medical technologies, while forcing makers of headphones or golf bags to pay more. "I don't think there is an obvious supply gap or hole where someone will not be able to get a Prius or Tesla or whatever they're looking at," Gholz says.

In the event of a longer Chinese supply interruption, the U.S. rare earths mine at Mountain Pass, Calif., would likely become the first place to step up production, Gholz explains. The mine's previous owner, Molycorp, spent approximately $1.5 billion building a new separation facility for producing rare earth concentrates. It did not, however, complete the downstream processing needed to produce purified rare earth materials before the company went bankrupt in 2015 because of Chinese competition. The mine's new owner, MP Materials, plans to reactivate and complete the mothballed facility for fresh operation starting in 2020.

Another alternative is Australian company Lynas Corp., the world's only significant rare earths producer outside China. It currently operates a mine at Mount Weld in Australia, and sends ores to a separation facility in Malaysia that can purify the rare earth materials-but a complication has arisen from the fact that some ores contain radioactive thorium. Environmental concerns about low-level radioactive waste from the separation facility recently led Lynas to announce it will move some some of the "upstream" processing (which involves the radioactivity) back to Australia, while keeping "downstream" processing in Malaysia. The company has also announced it will work with Texas-based Blue Line Corp. to build a new separation facility in the U.S. for operations starting in 2022 at the earliest.

Beyond existing mines, companies that dig for other resources might start extracting rare earth elements from deposits of different materials. For example, the U.S. could someday obtain these elements as byproducts from power plant coal ash and coal mining waste. And radioactive material mixed in with ores could end up being positive: If thorium-based nuclear plants prove viable, expanded thorium mining would also turn up usable rare earth minerals. Researchers have even begun investigating a large concentration of rare earth elements in deep-sea mud from an ocean floor deposit near Japan.

Less Is More

Some industries that rely on rare earth elements are going outside the box and looking for ways to bypass mining entirely. After all, such operations in China and elsewhere have significant environmental impacts that can threaten human health in the absence of strict regulation. The presence of radioactive thorium in some ore is one example. In addition, some mining and separation processes involve chemicals that produce toxic wastewater. All of these dangerous byproducts require scrupulous storage and disposal.

With China threatening to weaponize its advantage when it comes to rare earth elements, more companies may invest in innovations that could replace these materials with something else. Gholz points to a 2010 incident in which China temporarily cut off Japan from its supply of rare earth elements. Afterward, Japanese automakers such as Toyota and Honda began developing hybrid car motors that greatly reduced or even eliminated rare earth elements, such as terbium and dysprosium, from the powerful magnets used in electric motors.

During the 2010 supply scare, other large industries that used rare earth elements also discovered they could do without some of them. Oil refinery operators temporarily stopped using the rare earth element lanthanum, which improves oil refining efficiency, when the price went up. The glassmaking industry largely abandoned using the rare earth element cerium for polishing. Although industries related to national security would be unable to entirely forgo rare earth minerals, Gholz thinks the U.S. military's demand could be "easily satisfied by non-Chinese production" because this need represents less than 5 percent of the total market.

Reduce, Reuse, Recycle

In any case, a variety of industries will continue to rely heavily on rare earth minerals. To obtain them without depending on Chinese or U.S. mines, they could recycle those elements already used in products, says Eric Schelter, a professor of chemistry at the University of Pennsylvania, whose research projects include developing new chemical processes for separating rare earth elements from ore. "The appeal here is that there has already been a significant energy input and waste output to purify rare earth elements from their ore materials," he says. "Simply throwing them away is therefore wasteful, considering that in technological devices, they are typically relatively pure compared to their ores."

He pointed to many research projects at both academic and government labs: the latter include the U.S. Department of Energy's Critical Materials Institute at the Ames Laboratory and the Oak Ridge National Laboratory. For example, rare earth elements such as neodymium and dysprosium are frequently combined in permanent magnets. To separate them, Schelter's lab has developed chemical processes that can selectively dissolve one rare earth element while the other remains solid. It's a "fast and efficient approach to metals separation," he says, but the cost is currently not competitive with mining. Still, he thinks that could change because the market price of rare earth elements is currently kept "artificially low"-it does not account for the cost of waste treatment and handling during the mining and separation processes. If the recycled versions of these materials were marketed as cleaner alternatives to mined rare earth elements, it might encourage companies seeking a greener image to pay more for them.

"Consumers recognize the importance of free trade coffee and consequences of blood diamonds," Schelter says. "It stands to reason that ethical cobalt and clean or recycled rare earth elements can contribute to a more sustainable picture for this industry."

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As trade tensions rise between the U.S. and China, rare earth minerals are once again in the political spotlight. Today Chinese mines and processing facilities provide most of the world's supply, and Chinese leader Xi Jinping has hinted about using this as political leverage in trade negotiations with U.S.

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Cracking! | Exhibition chemistry | RSC Education

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Cracking! | Exhibition chemistry | RSC Education

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Cracking hydrocarbons in liquid paraffin with a catalyst | Experiment | RSC Education

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Cracking hydrocarbons in liquid paraffin with a catalyst | Experiment | RSC Education

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Glass Education & Videos

Below is a collection of glass related information and video clips that we have prepared and collected for the general science enthusiast. This also includes material provided by other researchers and links to other great resources available on the web. Let us know if you have other good resources to add!

Sugar Glass - Exploring glass science through hard candy

Sugar Glass

The materials below are designed to provide a low-cost, hands-on approach to exploring aspects of real material science, focusing on glass science. One of our favorite glass materials is candy glass, an unflavored variety of "hard candy". This can be made from common kitchen ingredients including cane sugar (sucrose), corn syrup and water. The experiment introduces the student to properties of the glass state, how to make their own glass-like materials and interesting experiments from fiber pulling to refractive index, from crystallization kinetics to measiring the glass transition temperature by thermal analysis - all from the kitchen lab. Click to View Video>
Our emphasis is on learning science through participation with materials and experiments. While our hands-on activities are all designed to be low-cost, they still capture real material science principles and remain open-ended. Some of our more advanced experiments include the using simple micro-controllers and electronic ICs to build powerful instruments for measurement and control.

Educational Resources for Teachers

Teacher Workshop: Candy Glass Workshop as undertaken at the 2012 American Association of Physics Teachers (AAPT) Meeting. Includes links to general information; discussion slides; experiments & procedures; other related home-built glass science

Introduction to Glass and Sugar Glass Experiments

Sugar Glass demo video of lecture with candy glass making and fiber pulling activity by Bill Heffner, IMI-NFG, Aug. 2007 (Total running time: 46 minutes, streamed video file).

Summary of all Low Cost, Hands On Experiments:

Building a Low Cost, Hands-On Learning Curriculum for Glass Science & Engineering Using Candy Glass, An Overview. (Mat. Res. Symp. Proc. Vol 1233, Fall 2009). A paper by W. Heffner and H. Jain (PDF file)

Low-Cost, Experimental Curriculum in Materials Science Using Candy Glass Part 2: Home-Built Apparatuses, W. Heffner and H. Jain, presented at MRS Fall 2013 Meeting.

How to Make Candy Glass - with Simple Recipe

Experiments with Candy and Candy Glass

Refractive Index of Sugar Glass

General Experiments: Fiber Drawing and Related Experiments: Refractive Index and Density Experiments: Crystallization in Glass Experiments:
Thermal Analysis and Glass Transition Experiments:

Home built DTA with both heating and cooling option.

Electrical Conductivity and Glass Transition:
Other useful links:
"Edible Glass" : link to educational pages from Cornell website.

Glass Fracture - Understanding the science around us

From broken windows to auto crash scenes, most of us already have observed some of the unique features characteristic of the "glass fracture". In the materials below explores and explains some of these familiar observations as well as some of the techniques that scientists are using to improve the strength and safety of glass.

Glass Fracture from Sandia Labs

Sandia Presentation on Glass Fracture and Strengthening
by Dr. Jill Glass, Sandia Laboratories. This PDF presentation illustrates example of glass fractureand discussed strengthening through ion exchange methods.

SandiaVideo - bending plate
This video provides a powerful illustration of the enormous improvement in strength (and flexural extent) possible from modifying the glass surface. This video was provided by Jill Glass of Sandia National Laboratories.

Exploding window Video - Sandia
This video illustrated the danger one faces from a simple glass window during an explosion and the highlights the concern for improving the way ion which glass fractures. The video was made at New Mexico Tech for Sandia National Laboratories.

Glass Fracture from Penn State University

Some interesting information on brittle fracture can be found on Penn State University website of David Green at: http://www.ems.psu.edu/~green/djg.html

Museum of Glass

International Collaboration on Glass Mechanics (ICGM)

Glass Strength and Flaws and ICGM site by C.R. "Chuck" Kurkjian provides a nice paper presented by Kurkjian and W.R. (Bill) Prindle at the 1st International Congress on Ceramics in Toronto, Canada in June 2006. It provides a personal view of some history of glass mechanics as well as a "roadmap" for stronger glass. Link to Kurkjian´s history paper

Other interesting links

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Below is a collection of glass related information and video clips that we have prepared and collected for the general science enthusiast. This also includes material provided by other researchers and links to other great resources available on the web. Let us know if you have other good resources to add!

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The difference between alkanes and alkenes.

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Folding glass: how, why, and the truth of Samsung’s Z Flip - The Verge

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Folding glass: how, why, and the truth of Samsung’s Z Flip - The Verge

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On February 11th, 2020, Samsung introduced the world's first folding glass phone: the Galaxy Z Flip. Samsung declared that it had broken the laws of physics by bending glass, specifically by making "a leap from polymer screens to ultra-thin glass technology."

Samsung made it sound like it had invented a new proprietary form of glass, and the company even dubbed it Samsung Ultra Thin Glass (UTG). "We've done the impossible and created ultra thin glass that folds," the company's presentation claimed, adding that it "protects your screen from scratches."

But as the world would see days later, physics isn't so easy to ignore.

Glass experts could have warned you about what happened next, when it turned out that Samsung's supposed "leap" does use polymer and is easy to scratch after all. Samsung's dust-resistant "fiber shield" immediately went on to fail an aggressive dust test, and the company's claims around glass have now retreated to the ridiculous tagline "tough, yet tender."

But Samsung didn't lie about the primary innovation here: the Galaxy Z Flip is truly a folding glass phone. It's just that glass is actually made by German manufacturer Schott, it's got a soft, scratchable plastic layer up top, and - hopefully - future folding glass phones won't require that extra protection.

To understand why, you should probably first understand how glass can fold at all.

Flexible glass is real

If I'm being honest, I'm still wrapping my head around it myself. Glass is fragile; even if you've somehow never broken glass yourself, you definitely know how it sounds when it shatters. It's tough to even imagine how such a brittle material could be turned into a bendable flip phone, which is why I'm not surprised when Samsung found itself facing accusations that the Galaxy Z Flip's ultra-thin glass might not be glass at all.

And yet the physics of folding glass is remarkably simple, according to two material scientists, as well as representatives from Gorilla Glass maker Corning and Schott itself. The short version: practically anything can be bent if you make it thin enough.

"One of the most common misconceptions about glass is that it breaks because it's inherently weak" - Corning

"All the materials we know of that are very rigid can be bent to some extent," says Schott's Dr. Mathias Mydlak, a chemist who now leads business development for the company's ultra-thin glass. "If you think of wood, a 2x4 cannot be bent, but if you chisel a very fine piece of it [...] the same is true for glass," he told me late last year. While a normal windowpane might not seem to bend before breaking, a thin enough ribbon of glass actually can.

When you bend a material, glass or otherwise, what you're doing is naturally stretching the material on the outside of your bend - and even glass has some flex. "You could imagine a metallic spring between every two atoms and the spring elongating when you stretch the two atoms apart," says Erkka Frankberg, a research fellow at Tampere University who studies unconventional forms of glass.

The main gotcha: you can only stretch a material's chemical bonds so far before it breaks, a concept known as tensile strength. But if you use a thinner sheet of glass, you're stretching less of the material across the same space, bending fewer layers and stretching fewer chemical bonds, Mydlak says. That puts less tensile strain on the glass, letting you bend it tighter before it snaps. Thinning out the glass is one of the "two main tricks" to making it bend, says MIT associate professor of materials science Juejun Hu, because physics students learn that tensile strain scales linearly with thickness.

When you get glass down below a hundred microns thick - around the thickness of a human hair - that's when it can bend far enough for basic folding gadgets, experts say. If you want a phone that folds inward without a huge hinge gap, we're talking tens of microns. Think aluminum foil.

That thinness is already possible with glass that exists today. I touched a 70-micron sheet of Schott glass four years ago, and bent it with my own hands. Samsung says its Z Flip uses a 30-micron-thick glass, and Schott says it's gone down to 25 microns in the lab as well. Both Corning and Schott use somewhat similar techniques, each creating a floating glass sheet in midair by drawing thin ribbons of molten glass out of specially shaped vats.

But thin isn't enough by itself. The second "main trick" for bendable glass is to strengthen it against imperfections, particularly at the surface where they can cause catastrophic failures when the glass is stressed. A tiny air bubble, speck of dirt, or minuscule scratch during the manufacturing or handling process might be enough to destroy a piece of bendable glass, experts say. "All the stresses you produce in the glass tend to concentrate on those small defects, and that's where it will produce a fracture," says Frankberg.

That's where chemical baths and heat treatments can come in to strengthen and temper the glass, as we've written about before, but the trade-off is that they can make glass easier to scratch. And as your glass gets thinner - thin enough to bend - a scratch becomes even more worrying.

Scratches are deadlier

While Mydlak says that a piece of Schott's glass "can go on forever" in controlled conditions if it survives the first bend test, he admits that one scratch could change that. "If you scratch it with something ... this is going to be an initial defect that can cause problems later on," he says. If a piece of glass with a large enough scratch is bent with enough stress concentrated on a "pre-crack," says Frankberg, "it will basically propagate with the speed of sound and catastrophically go through the whole material."

The thing to remember is that while glass is more scratch resistant than plastic, it's not scratchproof - it may scratch at a Mohs hardness of 5 or 6, instead of 2 or 3 for plastic, but it scratches anyhow. I bet you have some tiny scratches on your phone's traditional glass screen right now. But I'm also guessing you never need to bend your traditional screen like you would with a folding phone. Now it's a way bigger deal.

Frankberg thinks that's probably why Samsung's Galaxy Z Flip still has a plastic screen protector up top. Not to prevent scratches or help it bend more easily, but as a "sacrificial layer" that gets scratched instead of the glass, so there are fewer potential catastrophic cracks down the road. "Probably they receive fewer product returns due to the extra layer," he speculates.

Schott's Mydlak actually hinted as much to me late last year, before the Z Flip was announced: "Most probably you would not be touching the bare glass at all, but something on top of it," Mydlak said when I asked about whether scratches would be something to worry about with the first batch of folding glass phones.

I should add that we don't fully know what Samsung and its partners are doing with Schott's glass screen before adding it to the phone. Schott could only confirm that it's delivering its ultra-thin glass to Samsung, saying that it "cannot comment on any processing details of the raw glass material." And while Samsung has admitted that it comes with a pre-installed screen protector, the company announced on Wednesday that it's also "injecting" the glass "with a special material up to an undisclosed depth to achieve a consistent hardness," whatever that means. Samsung hasn't been willing to say more, and it sounds fairly hush-hush.

But Samsung does have another partner involved in that process. It's been working with Korean screen manufacturer Dowoo Insys on this glass since 2013, Yonhap News reports, and recently locked it down by becoming the largest shareholder in the company. Allegedly, Samsung has an exclusive on Dowoo's process but not Schott's ultra-thin glass, and Samsung reportedly decided to use both for the Galaxy Z Flip's screen.

What good is glass?

All of this still doesn't answer the question, though: what good is foldable glass if it scratches like plastic anyhow? One answer is that it may last longer; Schott says glass won't break down like plastics naturally do over time. There's also optical clarity to consider. Plus, as Dieter Bohn noted, the Galaxy Z Flip's glass - polymer cover or no - just plain feels nicer than the pure-plastic-covered original Galaxy Fold. The crease at the fold is less prominent and though it can be indented with a fingernail, it feels firmer than what's on the Galaxy Fold.

But Gorilla Glass maker Corning wants you to know the Galaxy Z Flip's screen protector may not be necessary in a year or two. The company tells me samples of its new bendable glass are already in the hands of device manufacturers. It expects devices in the market in the next 12 to 18 months, and it's shooting to deliver "durability, scratch resistance, and optical clarity" all in a single package for foldable devices.

While a rep couldn't yet say how Corning's doing that or explicitly confirm there'd be no plastic involved, plastic doesn't appear to be the goal: "Today, when you buy a phone with Gorilla Glass, you're touching glass ... that's what we're working towards."

Mass-producing glass thin enough to reliably bend is a tough challenge, Corning and Schott agree. Mydlak told me last year that Schott was still figuring out a few production issues, like how to properly cut, pack, and ship reels of the very thinnest glasses it had developed without damaging them along the way. It sounds like the existence of the Galaxy Z Flip means it's worked some of that out - but low yields also may be one of the reasons folding phones are so incredibly expensive, and why Corning has yet to fully figure it out.

It's hard to blame Samsung for pushing so hard, even if both its foldables have stumbled out of the gate - for one thing, it wants to sell folding screens to other companies, too, as it all-but-revealed in its latest press release. But that doesn't make it any less frustrating to see that a phone that was promised as scratch-resistant can easily be scratched, and it doesn't mean you need to buy in. Though if you do, Samsung tells The Verge that you can get a free screen protector and / or a one-time $119 screen replacement if your device does succumb to scratches.

Frankberg isn't yet convinced. "My honest opinion as a materials scientist: I wouldn't buy these kinds of phones at this stage because the size of the scratch you need to break it is very very small," he says, pointing out how a single grain of sand could destroy a folding glass screen. "Buying a very expensive phone, I would step back and see how the technology improves."

Mind you, Frankberg has an idea of how such screens might eventually evolve: he's in the very early stages of developing a form of glass that uses aluminum oxide instead of the traditional silica, one that can bend instead of breaking, and is exploring other alternative materials, too. (It wouldn't be the first time the world's looked into "alumina" glass, and you may also be familiar with aluminum oxide's condensed crystalline form, sapphire.)

I just wonder if we'd actually call such a material "glass" if or when it ever arrives. Like JerryRigEverything's Zack Nelson is fond of saying when he scratch-tests a new glass screen, it's hard to shake the stereotype. "Glass breaks. If anyone ever comes up with something stronger than glass, they'll definitely be calling it something different."

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Folding glass: how, why, and the truth of Samsung's Z Flip

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The Galaxy Z Flip is truly a folding glass phone, but Samsung didn't invent the glass and it's not glass alone - it's made by German manufacturer Schott and has a soft, scratchable plastic layer up top. Here's how folding phones work and why they hopefully won't need protective layers for long.

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How is tempered glass made? - Scientific American

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How is tempered glass made? - Scientific American

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Advertisement

Mark Ford, fabrication development manager at AFG Industries, Inc., explains:

Tempered glass is about four times stronger than "ordinary," or annealed, glass. And unlike annealed glass, which can shatter into jagged shards when broken, tempered glass fractures into small, relatively harmless pieces. As a result, tempered glass is used in those environments where human safety is an issue. Applications include side and rear windows in vehicles, entrance doors, shower and tub enclosures, racquetball courts, patio furniture, microwave ovens and skylights.

To prepare glass for the tempering process, it must first be cut to the desired size. (Strength reductions or product failure can occur if any fabrication operations, such as etching or edging, take place after heat treatment.) The glass is then examined for imperfections that could cause breakage at any step during tempering. An abrasivesuch as sandpapertakes sharp edges off the glass, which is subsequently washed.

Next, the glass begins a heat treatment process in which it travels through a tempering oven, either in a batch or continuous feed. The oven heats the glass to a temperature of more than 600 degrees Celsius. (The industry standard is 620 degrees Celsius.) The glass then undergoes a high-pressure cooling procedure called "quenching." During this process, which lasts just seconds, high-pressure air blasts the surface of the glass from an array of nozzles in varying positions. Quenching cools the outer surfaces of the glass much more quickly than the center. As the center of the glass cools, it tries to pull back from the outer surfaces. As a result, the center remains in tension, and the outer surfaces go into compression, which gives tempered glass its strength.

Glass in tension breaks about five times more easily than it does in compression. Annealed glass will break at 6,000 pounds per square inch (psi). Tempered glass, according to federal specifications, must have a surface compression of 10,000 psi or more; it generally breaks at approximately 24,000 psi.

Another approach to making tempered glass is chemical tempering, in which various chemicals exchange ions on the surface of the glass in order to create compression. But because this method costs far more than using tempering ovens and quenching, it is not widely used.

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Mark Ford, fabrication development manager at AFG Industries, Inc., explains: Tempered glass is about four times stronger than "ordinary," or annealed, glass. And unlike annealed glass, which can shatter into jagged shards when broken, tempered glass fractures into small, relatively harmless pieces. As a result, tempered glass is used in those environments where human safety is an issue.

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GLASS FACT: HISTORY OF GLASS * Glass Production

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GLASS FACT: HISTORY OF GLASS * Glass Production

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Where and when glass production began is uncertain. It is thought by some that the first glass was probably developed in the Mitannian or Hurrian region of Mesopotamia, possibly as an extension of the production of glazes (5000 BCE). Glass objects dated back to 2500 BCE have been found in Syria, and by 2450 BCE, glass beads were plentiful in Mesopotamia. Glass came later in Egypt, with its manufacture appearing as a major industry around 1500 BCE. The oldest glass of undisputed date found in Egypt dates from 2200 BCE.

In the beginning it was very hard and slow to manufacture glass. Glass melting furnaces were small and the heat they produced was hardly enough to melt glass. But in the 1st century BC, Syrian craftsmen invented the blow pipe. This revolutionary discovery made glass production easier, faster and cheaper. Glass production flourished in the Roman Empire and spread from Italy to all countries under its rule. In 1000 AD the Egyptian city of Alexandria was the most important center of glass manufacture. Throughout Europe the miraculous art of making stained glass on churches and cathedrals across the continent reached its height in the finest Chatres and Conterbury cathedral windows produced in the 13th and 14th centuries.

By 1575, English glassmakers were made glass in Venetian fashion. In 1674, an English glassmaker George Ravenscroft invented lead glass.

The first glass factoryin the United States was built in Jamestown, Virginia in 1608.

In the early 1800's, there was a great demand for window glass which was called crown glass. In the 1820s, the age of blowing individual bottles, glasses and flasks was ended by the invention of a hand-operated machine. In the 1870s, the first semi-automatic bottle machine was introduced.

After 1890, glass use, development and manufacturebegan to increase rapidly. Machinery has been developed for precise, continuous manufacture of a host of products. In 1902, Irving W. Colburn invented the sheet glass drawing machine which made possible the mass production of window glass. In 1904, the American engineer Michael Owens patented automatic bottle blowing machine.

In 1959 new revolutionary float glass production was introduced by Sir Alastair Pilkington by which 90% of flat glass is still manufactured today.

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GLASS FACT: HISTORY OF GLASS * Glass Production

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Where and when glass production began is uncertain. It is thought by some that the first glass was probably developed in the Mitannian or Hurrian region of Mesopotamia, possibly as an extension of the production of glazes (5000 BCE). Glass objects dated back to 2500 BCE have been found in Syria, and by 2450 BCE, ...

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Oil or petroleum is a readily combustable fossil fuel that is composed mainly of carbon and hydrogen, and is thus known as a hydrocarbon. The formation of oil takes a significant amount of time with oil beginning to form millions of years ago. 70% of oil deposits existing today were formed in the Mesozoic age (252 to 66 million years ago), 20% were formed in the Cenozoic age (65 million years ago), and only 10% were formed in the Paleozoic age (541 to 252 million years ago). This is likely because the Mesozoic age was marked by a tropical climate, with large amounts of plankton in the ocean.

The formation of oil begins in warm, shallow oceans that were present on the Earth millions of years ago. In these oceans, extremely small dead organic matter - classified as plankton - falls to the floor of the ocean. This plankton consists of animals, called zooplankton, or plants, called phytoplankton. This material then lands on the ocean floor and mixes with inorganic material that enters the ocean by rivers. It is this sediment on the ocean floor that then forms oil over many years. The energy in oil initially comes from the Sun, and is energy from sunlight that is trapped in chemical form by dead plankton.

Formation Process

The process that creates oil is generally the same in most areas, although there may be different types of plant and animal debris that falls to the ocean floor and slightly different conditions. To form oil, the following steps have to happen:

1. Dead plankton - both phytoplankton and zooplankton - as well as algae and bacteria sink to the bottom of an ancient ocean and mix with inorganic, clay-like materials that enter these oceans from streams and rivers. This creates an organic-rich mud. This mud can only form in still water environments. This step is shown in Figure 1, panel A.

2. This mud cannot be exposed to too much oxygen, or else the organic matter in the mud would be decomposed by bacteria and disappear quickly. Therefore environments where oil can form are known as anoxic environments. Before this organic matter is destroyed, it is buried by more sediment and lithifies (becomes sedimentary rock), creating organic shale. This step is shown in Figure 1, panel B. Burying material underwater is an easy way to create an anoxic environment because the atmosphere is not interacting with the decaying matter.

3. If this shale is buried between 2 and 4 kilometers, its temperature increases due to its location in the Earths interior. This increasing pressure and temperature of the shale transforms it into a waxy material known as . Shale that contains this material is known as .

4. If temperatures of the kerogen are greater than 90°C but lower than 160°C, the kerogen is transformed into oil and natural gas. At temperatures higher than this, only natural gas (literally a gas that's a hydrocarbon) or graphite is formed. This temperature range is known as the "oil window".

5. Oil is lighter than water, so as it escapes from the source oil shale it rises through pores in rocks, displacing water. Rock bodies that contain significant amounts of oil are known as reservoir rocks. For the oil to remain trapped in the reservoir, there must be some sort of thick, impermiable layer of rock to seal the reservoir. If this seal exists, then oil, gas, and water are trapped beneath and can be drilled into to obtain the oil.

6. Geological changes in the Earth's crust bring these deposits up closer to the surface, making them somewhat easier to access. This step is shown in Figure 1, panel C.

For Further Reading

References

1. Art Goldstein. (May 11, 2015). Formation of Oil [Online]. Available: http://f03.classes.colgate.edu/fsem037-oil/formation_of_oil.htm

2. Colgate University. (January 7, 2016). Oil Formation [Online]. Available: http://f03.classes.colgate.edu/fsem037-oil/formation_of_oil.htm/

3. R. Wolfson. Energy, Environment and Climate, 2nd ed. New York, U.S.A.: Norton, 2012, pp. 96-97

4. Created internally by a member of the Energy Education team

5. Stephen Marshak. (May 11, 2015). Earth: Portrait of a Planet, 3rd ed. New York, NY, U.S.A:W.W. Norton & Company, 2008

6. Canadian Federation of Earth Sciences. (May 11, 2015). Four Billion Years and Counting: Canada's Geological Heritage, 1st ed. Toronto, ON, Canada.: Nimbus Publishing, 2014

7. J. Kraushaar, R. Ristinen. (May 11, 2015).Energy and the Environment, 2nd ed. Hoboken, NJ, U.S.A.: John Wiley & Sons, 2006, pp. 54

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Oil or petroleum is a readily combustable fossil fuel that is composed mainly of carbon and hydrogen, and is thus known as a hydrocarbon. The formation of oil takes a significant amount of time with oil beginning to form millions of years ago.

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The chemistry of pottery | Feature | RSC Education

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The chemistry of pottery | Feature | RSC Education

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The Glass Bakery - Nova Scotia Fused Glass Birds and Gifts – The Glass Bakery Ltd

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The Glass Bakery - Nova Scotia Fused Glass Birds and Gifts – The Glass Bakery Ltd

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Percentage of Sales to ElderDog Canada and Misfit Manor Dog Rescue

Canine inspired Art for ElderDog Canada; and feel-good savings on "Misfits" for Misfit Manor Dog Rescue!

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Hanging Pocket Goldfinch

Cute as a button and not much bigger! This little Goldfinch ornament proves beauty comes in all sizes! He's the size of a Canadian Toonie. $28

Visit the Goldfinch

Nature's Gifts

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No molds, paints or glazes. Just glass.

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Close [video_title] video

Birds. Your link with Nature.

A collectable series of whimsical, happy shoreline and woodland bird ornaments. So much more than your average decorative object - these birds have personality! They're charming and beautiful in their simplicity. Delightful and unique.

A love of birds and nature benefits both physical and mental health, and nurtures our interest in the environment. Birds are a great choice for a gift whether for the home of office, and they transcend age and occasion.

Each glass bird is handcrafted, first by designing, then cutting shapes from clear glass and building layers of finely powdered coloured glass between the clear shapes. Next, the glass pieces are kiln-baked, fused at ultra high temperatures then strengthened by a controlled cooling. No paints, glazes or moulds are used. No two birds are the same. I initial each piece on the reverse.

Select a bird you see in your garden or along the shore; the chick that reminds you of a special time, person or place; or the bird that simply draws out your smile! Each bird reveals their own personality, and that special one will speak to you, asking you if they can come home!

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The Glass Bakery - Nova Scotia Fused Glass Birds and Gifts

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Canine inspired Art for ElderDog Canada; and feel-good savings on "Misfits" for Misfit Manor Dog Rescue! Dog Rescue Glass Cute as a button and not much bigger! This little Goldfinch ornament proves beauty comes in all sizes! He's the size of a Canadian Toonie.

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Corelle Archives - Page 2 of 6 - Lead Safe Mama

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Corelle Archives - Page 2 of 6 - Lead Safe Mama

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Corelle Archives - Page 2 of 6 - Lead Safe Mama

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To see more Corelle pieces I have tested, Click HERE. This post includes XRF test results for metals found in a vintage Corelle plate with the green Crazy Daisy / Spring Blossom Green pattern along the edge on the food surface of the dish. Originally published November 19, 2018 Updated December 2, 2019 Introduction: Tamara ...

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The Ohio Oil and Gas Energy Education Program (OOGEEP) is a non-profit statewide education and public outreach program. Created in 1998, OOGEEP provides a variety of programs throughout the State of Ohio.

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Parlon (Chlorinated Rubber) | Fireworks Cookbook

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Parlon (Chlorinated Rubber) | Fireworks Cookbook

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Parlon is an acetone-soluble polymer that is used as a chlorine donor and binder. It is a good example of one of the new chemicals that has become available in the past few decades for use in compositions.

In stock

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Parlon (Chlorinated Rubber) | Fireworks Cookbook

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Parlon is an acetone-soluble polymer that is used as a chlorine donor and binder. It is a good example of one of the new chemicals that has become available in the past few decades for use in compositions. In stock

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Plastic Materials | Free Online Database for Plastic Industry

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Plastic Materials | Free Online Database for Plastic Industry

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Plastic Materials | Free Online Database for Plastic Industry

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Search for polyolefins, PVC, engineering plastics, elastomers, etc. with Omnexus - Free access to technical datasheets, selection guides, tutorials, brochures...

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Ceramics is a category of hard material that is typically manufactured by heating minerals. Humans have produced ceramics since at least 24,000 BC. This predates the use of metal. Modern ceramics include some of the strongest known materials. Ceramics are commonly used in construction, consumer products, vehicles, scientific and industrial equipment. The following are common types of ceramics.An ancient type of ceramics that developed in China as early as the Shang dynasty of 1600-1046 BC. Porcelain comes in many varieties that are based on heating a clay mineral known as kaolin in a kiln, a type of oven.A type of porcelain made with bone ash as an key ingredient. This is a British innovation that emerged at the end of the 18th century. For about 150 years, bone china was produced almost exclusively produced in the UK with Japan entering the market in the mid-20th century. Ceramics is often defined as an inorganic material but bone china is an exception. The earliest form of human produced ceramics that was created in fire pits as early as 29,000 BC. Earthenware is made with selected clays and other materials and is not heated to the point of vitrification that gives porcelain and other ceramics their glassy, translucent and nonporous properties. As such, earthenware is opaque, porous and is softer than porcelain.Stoneware is fired at a temperature above earthenware but below porcelain. This results in a vitreous or semi-vitreous ceramic that is watertight but not as translucent and white as porcelain. A ceramic produced with a process of controlled crystallization that has properties similar to glass with the strength and durability of ceramics.Bricks produced by heating minerals such as sand and clay are ceramics.A common definition of a ceramic is a hard material that is held together with ionic and covalent bonds. According to this definition, elemental carbon is a ceramic. Additionally, carbon based materials such as carbon fiber, carbon nanotubes and graphene can be considered ceramics. Graphene is currently considered the strongest known material.

Properties

Carbon materials such as carbon fiber and graphene have a high specific surface area meaning that they can be formed into sheets that are extremely light weight. In theory, you can make a 2630 m ² sheet of graphene that only weighs one gram (28309 square feet with a weight of 0.035274 ounces). These materials have extremely high tensile and compressive strength and display remarkable electron mobility.

Example Uses

Advanced composite materials such as carbon reinforced plastic are used for high performance applications such as aviation, sporting goods and safety equipment. Carbon fiber also has broad applications in areas such as textiles, technology products and construction.

As with carbon, elemental silicon can be considered a ceramic due to its chemical properties. Silicate minerals are extremely abundant as they make up approximately 90 percent of the Earth's crust. Clays and sand that are used to create common ceramics are often silicon based. For example, the kaolinite used to make porcelain and the silica used to make fired bricks are silicate minerals.A semiconductor material containing silicon and carbon that occurs naturally as the very rare mineral moissanite. An extremely hard and heat resistant ceramic that has a black color.A material made with equal parts of tungsten and carbon that is dense and hard.A ceramic valued for its electrical properties. A hard ceramic that is resistant to heat, ionizing radiation and chemicals.A bioceramic is any ceramic material that is biocompatible, meaning that it can be safely used inside the human body. These are designed to be inert in the body and may be designed to decompose with time such that they are replaced by the body.A type of composite material made with ceramic fibers embedded in a ceramic matrix. Foam is any material that contains pockets of gas or liquid. Ceramic foams are typically designed to be strong and lightweight or to have special properties for applications such as thermal insulation.Ferrite is a ceramic material manufactured by heating rust (iron oxide) with one or more metals such as barium, nickel and zinc. Ceramics that contain a metal such as Titanium carbide are known as a cermet.

This is the complete list of articles we have written about materials.

If you enjoyed this page, please consider bookmarking Simplicable.

A list of common types of materials.

An overview of the common types of wood with photos.

A definition of compressive strength.

A definition of tensile strength with examples.

Common examples of composite materials.

A list of the common types of metal.

The basic characteristics of gold including its properties, financial and cultural significance.

A list of the common characteristics of sustainable materials.

A list of common building materials with their uses and properties.

A complete overview of bamboo wood.

The most popular articles on Simplicable in the past day.

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Ceramics is a category of hard material that is typically manufactured by heating minerals. Humans have produced ceramics since at least 24,000 BC. This predates the use of metal. Modern ceramics include some of the strongest known materials. Ceramics are commonly used in construction, consumer products, vehicles, scientific and industrial equipment.

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EducationProjects.org + Ohio Oil & Gas Energy Education Program: Looking below the surface / educationprojects.org

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EducationProjects.org + Ohio Oil & Gas Energy Education Program: Looking below the surface / educationprojects.org

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EducationProjects.org + Ohio Oil & Gas Energy Education Program

OOGEEP is a check-off program funding 100% by Ohio's natural gas and crude oil producers and royalty owners through a voluntary assessment on oil and gas produced in Ohio. These dollars are used for education and public outreach only. Nearly 17 years ago they approached us to design an education program.

We started by addressing hot topics such as oil spills, but quickly realized that teachers and students alike didn't know much about the process of getting oil and gas out of the ground. So we backed up and dealt with the basics:

Why is there oil and gas here? That's geology.

How is it found? That's physics and engineering.

How do they get it out of the ground? The flow of fluids to the surface-that's physics.

How is it transported? That's engineering and logistics.

What will be done with it? That's chemistry.

As the industry changes, so does our curriculum and workshop. In the past 5 years, we have added labs and experiments around hydraulic fracturing, seismic activity, water issues and petrochemicals.

We wanted to help teachers understand how the industry works and also to have balanced information about controversial issues, so they can speak knowledgeably.

Design

We convened a peer group of teachers and stakeholders to discuss the best approach and discovered a few items of importance:

1. Peer to peer training through professional development

2. Communications must include balanced information

3. Create industry-ed connections with site tours & industry contacts

4. Providing content the Executive Director could deliver

We pulled this information together, then used an innovative workshop design-peers teaching peers about how oil and gas production connects to science. The first program of this kind we tested the curriculum and lab work with the first workshop insuring success and making small changes along the way.

The instructional design was custom-built and included lessons, labs and hands-on experiments. Unlike other inquiries this client wanted to have active engagement in the teaching. The collaborative process included considerable input from the Executive Director to insure the design would support her goals.

Implementation

To adhere to one of our important directives regarding peer to peer training, we split the teachers into six groups. Each group learns something specific, then teaches their colleagues about what they've learned. This creates engaged learners-the teachers really seem to enjoy this method.

The learning and teaching are Day 1 of the workshop, and the participants get graduate credit for it. Day 2 is a field trip to related locations. We've visited fracking sites and reclaimed areas. The teachers can take pictures and walk all around, giving them access to the latest technology and how it's being used.

Communications and engagement has been consistent over 17 years building a trusted network of educators and stakeholders. The workshops fill quickly every summer. The teachers go home with $150 worth of classroom supplies and curricula and spread the word amongst their peer group. We have teachers trained in all 88 of Ohio's counties, and we see new teachers all the time. They take the supplies back to their schools and teach energy education in a variety of ways. We have trained K-12 teachers, so these science skills-physical science, environmental science, chemistry, geology, physics and more-are being presented at all different levels.

To support the online resources strategy we've added a page to the OOGEEP website called Show and Tell, where teachers' use of the materials are written into articles accompanied by classroom photographs. These accounts help communicate the usefulness of the workshop, lessons, field trips, and supplies.

Engagement continues as we've partnered with other educators from our network, bringing in people who have a strong background knowledge of geology. We added a 2-day geology workshop in the summer of 2017 that filled up 48 hours after posting. This curriculum was developed with the help of Ohio's former state geologist, members of the Ohio Department of Natural Resources and the Ohio State University Geology Department. As part of our outreach strategy, we have presented 1-3 hour workshops at the Science Education Council of Ohio, the National Science Teachers Association Conference, various regional Soil and Water Conservation Districts and various local School District professional development events.

Outcomes

Delivered workshop for 17 years

Awarded the "2005 Friend of Science" presented by the Science Education Council of Ohio

Won "Outstanding Project (Teacher Education)" presented by the Ohio EPA/Ohio Environmental Education Fund

Teachers trained from all 88 counties in Ohio

Executive Director teaches class and delivers tour!

Delivered "Show and Tell" framework for teacher sharing

Science skills being taught K-12 with this content

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EducationProjects.org + Ohio Oil & Gas Energy Education Program: Looking below the surface

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Design We convened a peer group of teachers and stakeholders to discuss the best approach and discovered a few items of importance: Peer to peer training through professional development Communications must include balanced information Create industry-ed connections with site tours & industry...

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Silver Series: Perfect Storm for Silver (Part 2 of 3) - Visual Capitalist

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Silver Series: Perfect Storm for Silver (Part 2 of 3) - Visual Capitalist

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When most people think about oil and natural gas, the first thing that comes to mind is the gas in the tank of their car. But there is actually much more to oil's role, than meets the eye...

Oil, along with natural gas, has hundreds of different uses in a modern vehicle through petrochemicals.

Today's infographic comes to us from American Fuel & Petrochemicals Manufacturers, and covers why oil is a critical material in making the EV revolution possible.

Pliable Properties

It turns out the many everyday materials we rely on from synthetic rubber to plastics to lubricants all come from petrochemicals.

The use of various polymers and plastics has several advantages for manufacturers and consumers:

Today, plastics can make up to 50% of a vehicle's volume but only 10% of its weight. These plastics can be as strong as steel, but light enough to save on fuel and still maintain structural integrity.

This was not always the case, as oil's use has evolved and grown over time.

Not Your Granddaddy's Caddy

Plastics were not always a critical material in auto manufacturing industry, but over time plastics such as polypropylene and polyurethane became indispensable in the production of cars.

Rolls Royce was one of the first car manufacturers to boast about the use of plastics in its car interior. Over time, plastics have evolved into a critical material for reducing the overall weight of vehicles, allowing for more power and conveniences.
Timeline:

1916
Rolls Royce uses phenol formaldehyde resin in its car interiors

1941
Henry Ford experiments with an "all-plastic" car

1960
About 20 lbs. of plastics is used in the average car

1970
Manufacturers begin using plastic for interior decorations

1980
Headlights, bumpers, fenders and tailgates become plastic

2000
Engineered polymers first appear in semi-structural parts of the vehicle

Present
The average car uses over 1000 plastic parts

Electric Dreams: Petrochemicals for EV Innovation

Plastics and other materials made using petrochemicals make vehicles more efficient by reducing a vehicle's weight, and this comes at a very reasonable cost.

For every 10% in weight reduction, the fuel economy of a car improves roughly 5% to 7%. EV's need to achieve weight reductions because the battery packs that power them can weigh over 1000 lbs, requiring more power.

Today, plastics and polymers are used for hundreds of individual parts in an electric vehicle.

Oil and the EV Future

Oil is most known as a source of fuel, but petrochemicals also have many other useful physical properties.

In fact, petrochemicals will play a critical role in the mass adoption of electric vehicles by reducing their weight and improving their ranges and efficiency. In According to IHS Chemical, the average car will use 775 lbs of plastic by 2020.

Although it seems counterintuitive, petrochemicals derived from oil and natural gas make the major advancements by today's EVs possible - and the continued use of petrochemicals will mean that both EVS and traditional vehicles will become even lighter, faster, and more efficient.

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Silver Series: Perfect Storm for Silver (Part 2 of 3) - Visual Capitalist

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When most people think about oil and natural gas, the first thing that comes to mind is the gas in the tank of their car. But there is actually much more to oil's role, than meets the eye... Oil, along with natural gas, has hundreds of different uses in a modern vehicle through petrochemicals.

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Preservation Brief 33: The Preservation and Repair of Historic Stained and Leaded Glass

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Preservation Brief 33: The Preservation and Repair of Historic Stained and Leaded Glass

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PRESERVATION BRIEFS

"Stained glass" can mean colored, painted or enameled glass, or glass tinted with true glass "stains." In this Brief the term refers to both colored and painted glass. "Leaded glass" refers generically to all glass assemblies held in place by lead, copper, or zinc cames. Because the construction, protection, and repair techniques of leaded glass units are similar, whether the glass itself is colored or clear, "stained glass" and "leaded glass" are used interchangeably throughout the text.

Glass is a highly versatile medium. In its molten state, it can be spun, blown, rolled, cast in any shape, and given any color. Once cooled, it can be polished, beveled, chipped, etched, engraved, or painted. Of all the decorative effects possible with glass, however, none is more impressive than "stained glass." Since the days of ancient Rome, stained glass in windows and other building elements has shaped and colored light in infinite ways.

Stained and leaded glass can be found throughout America in a dazzling variety of colors, patterns, and textures (Figure 1). It appears in windows, doors, ceilings, fanlights, sidelights, light fixtures, and other glazed features found in historic buildings (Figure 2). It appears in all building types and architectural styles-embellishing the light in a great cathedral, or adding a touch of decoration to the smallest rowhouse or bungalow. A number of notable churches, large mansions, civic buildings, and other prominent buildings boast windows or ceilings by LaFarge, Tiffany, Connick, or one of many other, lesser-known, American masters, but stained or leaded glass also appears as a prominent feature in great numbers of modest houses built between the Civil War and the Great Depression.

This Brief gives a short history of stained and leaded glass in America. It also surveys basic preservation and documentation issues facing owners of buildings with leaded glass. It addresses common causes of deterioration and presents repair, restoration, and protection options. It does not offer detailed advice on specific work treatments. Glass is one of the most durable, yet fragile building materials. While stained glass windows can last for centuries, as the great cathedrals of Europe attest, they can be instantly destroyed by vandals or by careless workmen. Extreme care must therefore be exercised, even in the most minor work. For this reason, virtually all repair or restoration work undertaken on stained and leaded glass must be done by professionals, whether the feature is a magnificent stained glass window or a clear, leaded glass storefront transom. Before undertaking any repair work, building owners or project managers should screen studios carefully, check references, inspect other projects, and require duplicate documentation of any work so that full records can be maintained. Consultants should be employed on major projects.

Glassblowers were among the founders of Jamestown in 1607, and early glass manufacturing was also attempted in 17th-century Boston and Philadelphia. Dutch colonists in the New Netherlands enjoyed painted oval or circular medallions that bore the family's coat of arms or illustrated Dutch proverbs. German colonists in the mid-Atlantic region also began early glass ventures. Despite the availability of good natural ingredients, each of these early American glassmakers eventually failed due to production and managerial difficulties. As a result, colonists imported most of their glass from England throughout the 17th and 18th centuries.

Social values as well as high costs also restricted the use of stained and other ornamental glass. This was particularly true with regard to churches. The Puritans, who settled New England, rejected the religious imagery of the Church of England, and built simple, unadorned churches with clear glass windows. Less than 1% of the Nation's stained and leaded glass predates 1700. Considering the enormous loss of 17th-, 18th-, and early 19th-century buildings, any window glass surviving from these periods is very significant (Figure 3). Every effort should be made to document and preserve it.

Despite many failed starts, the War of 1812, and British competition, American glass production increased steadily throughout the 19th century. Stained glass was available on a very limited basis in America during the first quarter of the 19th century, but American stained glass did not really emerge in its own right until the 1840s. The windows at St. Ann and the Holy Trinity Episcopal Church in Brooklyn, New York, made by John and William Jay Bolton between 1843 and 1848, are perhaps the most significant early American stained glass installation (Figure 4). Other important early stained glass commissions were the glass ceilings produced by the J. & G. H. Gibson Company of Philadelphia for the House and Senate chambers of the United States Capitol in 1859.

America's glass industry boomed during the second half of the 19th century. (And although stained and leaded glass is found nationwide, the manufacturing was based in the Northeast and Midwest, where good natural ingredients for glass, and coal reserves for the kilns were available. Moreover, nearly all of the nationally renowned studios were based in major metropolitan areas of the central and northeastern states--near the manufacturers that supplied their raw materials.) In response to this growth, the industry formed self-regulating associations that established guidelines for business and production. In 1879 the Window Glass Association of America was established, and in 1903 The National Ornamental Glass Manufacturers' Association, precursor of the Stained Glass Association in America, was formed.

The 60 years from about 1870 to 1930 were the high point for stained glass in the U.S. In the early years, American stylistic demands reflected those current in Europe, including various historic revivals, and aesthetic and geometric patterns. American patterns prevailed thereafter; they tended to be more vivid, brash, and bold (Figure 5).

After the 1893 Columbia World's Exposition, the Art Nouveau Style became the rage for windows. Sinuous nymphs, leggy maidens, whiplashed curves, lilies, and brambles became standard subjects until World War Among the leading proponents of the Art Nouveau Style were glassmakers John LaFarge and Louis Comfort Tiffany. Both men experimented independently throughout the 1870s to develop opalescent glass, which LaFarge was first to incorporate into his windows. Tiffany became the better-known, due in part to his prolific output.

He attracted world-class artists and innovative glassmakers to his studio. Today, "Tiffany" remains a household name. His favorite and most popular scenes were naturalistic images of flowers, colorful peacocks and cockatiels, and landscapes at sunrise and sunset (Figure 6). LaFarge, while appreciated in his own day, gradually slid into relative obscurity, from which he has emerged in recent decades. Tiffany and LaFarge are the greatest names in American stained glass.

In dramatic contrast to the American Art Nouveau style was the Neo-Gothic movement that became so popular for church and university architecture across the country. Charles J. Connick was a leading designer of medieval-style windows characteristic of the style (Figure 7).

Advocates of the Prairie Style, of whom Frank Lloyd Wright is the best known, rejected Tiffany's naturalistic scenes and Connick's Gothic imitations. (Figure 8). Wright's rectilinear organic abstractions developed simultaneously with the similar aesthetic of the various European Secessionists. The creation of this style was aided by the development of zinc and copper cames in 1893. These cames-much stiffer than lead-made it possible to carry out the linear designs of Prairie School windows with fewer support bars. At first, these windows had only an elitist following, but they were soon widely accepted and proliferated during the early 20th century.

By 1900, stained and leaded glass was being mass-produced and was available to almost everyone. Leading home journals touted leaded glass windows for domestic use, and a nationwide building boom created an unprecedented demand for stained and leaded art glass windows, door panels, and transoms. Mail order catalogs from sash and blind companies appeared, some offering over 100 low-cost, mass produced designs (although the same catalogs assured buyers that their leaded glass was "made to order") (Figure 9).

The fading popularity of the ornate Victorian styles, combined with inferior materials used for mass production, essentially eliminated the production of quality leaded glass. The last mail order catalogs featuring stained glass were published in the mid-1920s, and tastes changed to the point that the 1926 House Beautiful Building Annual declared: "the crude stained glass windows in many of the Mansard-roof mansions of the 'eighties [1880s] prove how dreadful glass can be when wrongly used."

Some creative efforts expanded leaded glass media in new directions. Lead-overlay or "silhouette" glass was one novelty that climaxed in the late 1920s and early 1930s. Some designers sandwiched glass between layers of hand-cut sheet lead, while others sandwiched the perforated sheet lead between layers of glass. These windows present a playful reversal from traditional stained glass; in "silhouette" glass the lead metalwork, rather than the glass, becomes the primary art form (Figure 10). However, such novelties failed to catch on during the Depression. World War II delivered the final blow and ornamental glass is seldom found in residential, commercial, and secular architecture after circa 1940. The great age of American stained glass was over. Fortunately, leaded glass panels survived in uncounted numbers throughout the country, and are now once again appreciated as virtually irreplaceable features of historic buildings.

Before deciding on any treatment for historic leaded glass, every effort should be made to understand-and to record-its history and composition. Documentation is strongly encouraged for significant windows. Assigning an accurate date, maker, and style to a stained glass window often requires extensive research and professional help. A documentation and recording project, however, is worth the effort and expense, as insurance against accidents, vandalism, fire and other disasters. The better the information available, the better the restoration can be. The following sources offer some guidelines for dating leaded windows.

Building Context

The history of the building can provide ready clues to the history of its leaded windows, doors, and other elements. The construction date, and dates of major additions and alterations, should be ascertained. Later building campaigns may have been a time for reglazing. This is especially the case with churches and temples. They were often built with openings glazed with simple or generic clear leaded glass. Stained glass was added later as finances allowed. Conversely, the windows may be earlier than the building. They may have been removed from one structure and installed in another (once again, this is more likely with religious structures). Bills, inventories, and other written documents often give clues to the date and composition of leaded glass. Religious congregations, fraternal lodges, historical societies and other preservation organizations may have written histories that can aid a researcher.

Inscriptions and Signatures

Many studios and artists affixed signature plates to their work-often at the lower right hand corner. In the case of Tiffany windows, the signature evolved through several distinct phases, and helps date the piece within a few years: Tiffany Glass Company (1886-1892), Tiffany Glass & Decorating Company (with address, 1892-1902), Tiffany Studios New York or Louis C. Tiffany (post 1902). (Tiffany Studios, like others, did not always sign pieces and the absence of an inscription cannot be used to rule out a particular studio or artist.) Windows may also feature dated plaques commemorating a donor. However, these do not always indicate the date of the window, since windows were often installed before a donor was found. Nevertheless, such marks help establish a reasonable date range.

Composition and Other Stylistic Elements

These elements are more subjective, and call for a fairly broad knowledge of architecture and art history. Do the windows fit the general style of the building? The style of the window may reflect a stylistic period (e.g., Arts & Crafts, Art Nouveau, Prairie School). The imagery or iconography of the windows may also reveal their overall historical context and establish a general time period.

Framing and Surround

Framing elements and the window surround can reveal information central to dating the window. Do moldings match other interior trim? Has the opening been altered? Is the window set in an iron frame (post-1850s), a steel frame (generally post-World War I), a cast stone or terra cotta frame (seen as early as the 1880s, but popular after 1900)?

Reinforcement and Leading Details

Does the window or other element have round bars or flat bars? Flat bars began to appear about 1890; round bars, used since the Middle Ages, remained in use until the 1920s, when flat bars supplanted them. Cames can also give dating clues. Zinc cames, for example, developed by Chicago Metallic in association with Frank Lloyd Wright, first appeared in 1893. In general, however, dating a window by the came alone is difficult unless it is disassembled to view the "heart" (center web) for millmarks. Over one hundred varieties of lead came were available in the early 20th century. Moreover, came was sometimes produced to look old. Henderson's Antique Leading from the 1920s was made "to resemble the old hand wrought lead" and also carried "easy-fix" clip-on Georgian-style ornaments.

Glass

The glass itself can help in dating a window. Opalescent glass, for instance, was patented by John LaFarge in 1879. Tiffany patented two variations on LaFarge's technique in the same year. (Opalescent glass is translucent, with variegated colors resulting from internally refracted light. It features milky colored streaks.) Pre-1880 glass is usually smooth translucent colored glass (painted or not); glass with bold, deep colors is typical of the 1880s and 1890s, along with jewels, drapery glass and rippled glass. But such flamboyance faded out with the rest of Victoriana by about 1910. However, stained glass styles of the late 19th century continued to appear in ecclesiastical buildings after they passed from general fashion. Leaded beveled plate glass was popular in residential architecture after 1890, and was used profusely until the 1920s.

The level of documentation warranted depends upon the significance of the window, but it is very important to document repair and restoration projects before, during, and after project work. Photographs will normally suffice for most windows. For highly significant windows, rubbings as well as written documentation are recommended. The leading patterns in such windows are complex, particularly in plated windows (which have several layers). Rubbings are therefore encouraged for each layer when restored; they are invaluable if a disaster occurs and reconstruction is required. Annotated rubbings of the leadwork should be done with a wax stone on acid-free vellum.

To document windows properly, inscriptions should be recorded word for word, including misspellings, peculiarities in type style, and other details. Names and inscriptions in or on windows can indicate ethnic heritage, particularly in churches or civic structures where windows often reflect styles and themes from the congregation or community's origins. Lastly, any conjectural information should be clearly noted as such.

The Importance of Context

Stained glass commissioned for a particular building was normally designed not only to reflect the shape of the opening but also to coordinate with other aspects of the overall setting such as the architectural style, adjacent materials, and interior decoration. The window opening, frame or sash colors, placement of the reinforcement, alignment with architectural elements, and orientation to natural light also establish the relationship between the stained glass and the building. The vibrant colors of opalescent glass, which can often be read from the exterior, and the linear designs of Prairie School windows, which often harmonize with both the interior and the exterior, are two examples that readily demonstrate the importance of architectural context to ornamental glass.

This important relationship between the glass and its setting, however, can be weakened or entirely lost over the years due to unsympathetic decorating schemes or building campaigns, damage, deterioration, inept repairs, or the mere accumulation of dirt.

Changes to the ornamentation and finish of the structural frame can have an especially pronounced effect on the overall appearance of a stained glass window or dome. In the Chicago Cultural Center dome the historic finishes of the ornamental cast iron frame have darkened considerably over the years, muting the dome's rich personality. In strong sunlight the glass is so dominant that the frame appears only as a silhouette. Restoring the vibrancy of the historic finish is necessary to recapture the equally important contribution of the frame to the original design intent of the dome. After careful investigation to document the historic appearance (right), a mock-up section of the frame was regilded with aluminum leaf (top). The dramatic effect of restoring the dome's overall context is readily apparent after only this small section of the frame was refinished.

Three elements of leaded glass units are prone to damage and deterioration: the glass itself; the decorative elements (mostly applied paint); and the structural system supporting the glass.

Glass Deterioration

Glass is virtually immune to natural deterioration. Most American glass is quite stable-due to changes in glass composition made in the mid-19th century, particularly the increased silica content and the use of soda lime instead of potash as a source of alkali. Rarely, however, glass impurities or poor processing can cause problems, such as minor discoloration or tiny internal fractures (particularly in opalescent glass). And all glass can be darkened by dirt; this can often be removed. However, while glass does not normally deteriorate, it is susceptible to scratching or etching by abrasion or chemicals, and to breakage.

The greatest cause of breakage or fracture is physical impact. Leaded glass in doors, sidelights, and low windows is particularly susceptible to breakage from accidents or vandalism. When set in operable doors or windows, leaded glass can crack or weaken from excessive force, vibration, and eventually even from normal use. Cracks can also result from improperly set nails or points that hold the window in the frame, or more rarely, by structural movement within the building. Leaded glass that is improperly annealed can crack on its own from internal stress. (Annealing is the process by which the heated glass is slowly cooled; the process is akin to tempering metal.) Glass can also disintegrate from chemical instability or the intense heat of a fire. Finally, windows assembled with long, narrow, angular pieces of glass are inherently prone to cracking. Often the cause of the cracks can be determined by the path they travel: cracks from impact typically radiate straight from the source. Stress cracks caused by heat or improper annealing will travel an irregular path and change direction sharply.

Deterioration of Painted Glass

Painted glass, typically associated with pictorial scenes and figures found in church windows, often presents serious preservation challenges. If fired improperly, or if poor quality mixtures were used, painted glass is especially vulnerable to weathering and condensation. Some studios were notorious for poorly fired paints (particularly those working with opalescent glass), while others had outstanding reputations for durable painted glass. Paints can be applied cold on the glass or fused in a kiln. Since they are produced from ground glass, enamels do not "fade," as often suggested, but rather flake off in particles. Several steps in the painting process can produce fragile paint that is susceptible to flaking. If applied too thick, the paint may not fuse properly to the glass, leaving small bubbles on the surface. This condition, sometimes called "frying," can also result from poor paint mixtures or retouching. Paint failure is more commonly caused by under firing (i.e., baking the glass either at too low a temperature or for too little time). Unfortunately, in American stained glass, the enamels used to simulate flesh tones were typically generated from several layers that were fired at too low a temperature. This means the most difficult features to replicate-faces, hands and feet-are often the first to flake away (Figure 11).

Structural Deterioration

The greatest and the most common threat to leaded glass is deterioration of the skeletal structure that holds the glass. The structure consists of frame members, and lead or zinc (and occasionally brass or copper) came that secures individual pieces of glass. Frame members include wood sash and muntins that decay, steel t-bars and "saddle bars" that corrode, and terra cotta or stone tracery that can fracture and spall (Figure 12). When frames fail, leaded glass sags and cracks due to insufficient bracing; it may even fall out from wind pressure or vibration.

Wood sash are nearly always used for residential windows and are common in many institutional windows as well. Left unprotected, wood and glazing compounds decay over time from moisture and exposure to sunlight-with or without protective storm glazing-allowing glass to fall out.

Steel frames and saddle bars (braces) corrode when not maintained, which accelerates the deterioration of the glazing compound and loosens the glass. Moreover, operable steel ventilators and windows are designed to tight tolerances. Neglect can lead to problems. Eventually, they either fail to close snugly or corrode completely shut. The leaded glass is then frequently reinstalled in aluminum window units, which require wider sections for equal strength and typically results in an inch or more of the glass border being trimmed. Instead of relocating glass in aluminum frames, historic steel frames should be repaired. Often the corrosion is superficial; frames in this condition need prepping, painting with a good zinc-enriched paint, and realigning in the frame.

Masonry frames typically last a long time with few problems, but removing leaded glass panels set in hardened putty or mortar can be nearly impossible; as a last resort, glass borders may have to be sacrificed to remove the window.

Occasionally, leaded glass was designed or fabricated with inadequate bracing; this results in bulging or bowing panels; leaded panels should generally not exceed 14 linear feet (4.25 m) around the perimeter without support. More often, the placement of bracing is adequate, but the tie-wires that attach the leaded panels to the primary frame may be broken or disconnected at the solder joints.

Lead and zinc cames are the two most common assembly materials used in stained and other "leaded" glass. The strength and durability of the leaded panel assembly depends upon the type of came, the quality of the craftsmanship, and the glazing concept or design, as well as on the metallic composition of the cames, their cross-section strength, how well they are joined and soldered, and the leading pattern within each panel. Came is prone to natural deterioration from weathering and from thermal expansion and contraction, which causes metal fatigue.

The inherent strength of the assembly system is also related to the cross-section, profile and internal construction of the came (Figure 13). Came can have a flat, rounded, or "colonial" profile, and aside from a few specialty and perimeter cames (U-channel), is based on a variation of the letter "H" and ranges from 1/8" (3.2mm) wide to 1 1/4" (38mm) wide. The cross-section strength of came varies depending on the thickness of the heart and flanges. Occasionally, came with reinforced (double) hearts or a steel core was used for rigidity, usually in doors and sidelights. Such came added strength at the expense of flexibility and was typically used for rectilinear designs, or for strategically placed reinforcement within a curvilinear design.

How the cames are joined in a leaded panel is crucial to their long-term performance. Poor craftsmanship leads to a weak assembly and premature failure, while panels fabricated with interlocking (weaving) cames and lapped leads add strength. Soldered joints often reveal the skill level of the artisan who assembled the window, and can give evidence of past repairs. Solder joints should be neat and contact the heart of the came--wherein lies its greatest strength. Came joints should be examined closely; large globs of solder commonly conceal cames that do not meet. (Lead cames typically crack or break along the outside edge of the solder joint; stronger zinc cames frequently break the solder itself where it bridges junctures.)

Leading patterns designed with inadequate support also contribute to structural failure. Panels with a series of adjacent parallel lines tend to hinge or "accordion," while lines radiating in concentric circles tend to telescope into a bulge. Stronger leading techniques, support bars, or specialty cames are sometimes required to correct poor original design. Minor sagging and bulging is to be expected in an old window and may not require immediate action. However, when bulges exceed 1½" (38mm) out of plane, they cross into a precarious realm; at that point, glass pieces can crack from severe sagging and pressure. If the bulged area moves when pressed gently, or if surrounding glass is breaking, it is time to address the problem before serious failure results.

Lead Came

Lead is a soft malleable metal (it can be scratched with a fingernail). It naturally produces a protective dark bluish-gray patina. In the mid-19th century, improved smelting processes enabled manufacturers to extract valuable metal impurities from lead, thereby producing 100% pure lead came. The industry reasoned that 100% pure lead came was superior to the less pure variety. Although pure lead came is very workable and contributes to intricate designs, time has proven it to be less durable than medieval came, which contained trace elements of tin, copper, silver, and antimony. Unfortunately, the misconception that pure lead had greater longevity continued throughout the glory years of leaded glass use in America. Most glass conservators use a 100-year rule of thumb for the general life expectancy of 19th century came. In the 1970s, "restoration lead" (ASTM B29-84) was developed based on metallurgic analyses of medieval cames, some of which have lasted for centuries. Restoration lead should always be used when releading historic windows, unless the original integrity will be compromised.

Zinc Came

Zinc came is more vulnerable to atmospheric corrosion (particularly from sulfuric acids) than lead, but has proven to be durable in America because it weighs 40% less than lead and its coefficient of expansion is 7% lower. Thus, it is somewhat less susceptible to fatigue from expansion and contraction. Moreover, it is ten times harder than lead, and has three times the tensile strength. Zinc came is strong enough to be self-supporting and requires little bracing to interrupt the window's design. While zinc came is perfect for the geometric designs of Prairie School windows, it is usually too stiff to employ in curvilinear designs. Zinc can also take several finishes, including a copper or black finish. (As a result, zinc can be mistaken for copper or brass.)

Other Came

Other metals, primarily solid brass and copper, were also occasionally employed as came. They are generally found only in windows between ca. 1890 and ca. 1920. Frank Lloyd Wright started with zinc in 1893, was plating the zinc with copper by the late 1890s, and using solid copper by 1906.

The level of cleaning, repair, or protection depends on the condition, quality, and significance of the glass, and, as always, the available budget. Hastily undertaken, overly aggressive, or poorly executed repairs can cause more damage than does prolonged deterioration. Repairs should, therefore, only be undertaken after carefully evaluating the condition of the glass-and only by professionals. Minor cracks, sagging, and oxidation are part of the character of historic leaded glass, and require no treatment. More extensive cracks, major bulges (generally, more than 1½" [38mm]), and other signs of advancing deterioration may call for intervention, but caution must always be exercised. And each window must be evaluated separately. In some cases, windows have bulged up to 4" (102mm) out of plane without harming the pieces of glass or risking collapse.

Cleaning

Perhaps the greatest virtue of stained glass is that its appearance is constantly transformed by the ever-changing light. But dirt, soot, and grime can build up on both sides of the glass from pollution, smoke, and oxidation. In churches the traditional burning of incense or candles can eventually deposit carbon layers. These deposits can substantially reduce the transmitted light and make an originally bright window muted and lifeless. Simply cleaning glass will remove harmful deposits, and restore much of its original beauty, while providing the opportunity to inspect its condition closely (Figure 14). The type of cleaner to use depends on the glass. Water alone should be tried first (soft water is preferable); deionized water should be used for especially significant glass and museum quality restorations. If water alone is insufficient, the next step is to use a non-ionic detergent. Occasionally, windows are covered with a yellowed layer of shellac, lacquer, varnish, or very stubborn grime that requires alcohol, or solvents to remove. Most unpainted art glass can be treated with acetone, ethanol, isopropyl alcohol, or mineral spirits to remove these coatings if gentler methods have failed. All chemical residues must then be removed with a non-ionic detergent, and the glass rinsed with water. (All workers should take normal protective measures when working with toxic chemicals.)

Painted glass must never be cleaned before the stability of the paint is confirmed, and only then with great caution. If the paint is sound, it can be cleaned with soft sponges and cloth. If the paint was improperly fired or simply applied cold, paint can flake off during cleaning and special measures are required such as delicate cleaning with cotton swabs. Occasionally, paint is so fragile the owner must simply document and accept the windows in their current state rather than risk losing the original surface. Fragile paint typically calls for an experienced glass conservator and more costly restoration measures.

Acidic, caustic, or abrasive cleaners should never be used. They can damage glass. Most common household glass cleaners contain ammonia and should not be used either. Cleaning products should have a neutral pH.

Repair

As with all elements in older and historic buildings, maintenance of leaded glass units is necessary to prevent more serious problems. It is essential to keep the frame maintained regardless of the material. Often, this simply entails regular painting and caulking, and periodic replacement of the glazing compound. Wood frames should be kept painted and caulked; new sections should be spliced into deteriorated ones, and epoxy repairs made where necessary. Masonry frames must be kept well pointed and caulked to prevent moisture from corroding the steel armature and anchors within.

Windows that leak water, are draughty, or rattle in the wind (or when gently tapped) may indicate that the waterproofing cement ("waterproofing") and sealants have deteriorated and maintenance or restoration is needed. Waterproofing is a compound rubbed over the window-preferably while flat on a table-and pressed under the came flange to form a watertight bond between the leading and the glass. Traditionally, waterproofing was made of linseed oil and whiting, and a coloring agent. (Hardening agents should not be included in the mixture; solvent-based driers should be used sparingly.) The waterproofing allows leaded glass in a vertical position (e.g., in windows) to be used as a weatherproof barrier. It does not provided adequate protection for leaded glass in a horizontal or arched position; leaded glass ceilings and domes must always be protected by a secondary skylight or diffusing skylight.

Glazing and sealants (e.g., putties, caulks) are used to seal the leaded panel against the sash, and to seal any open joints around the window frame. Sealants improved dramatically in the mid-twentieth century. But these sealants are not without problems. Some release acetic acid as they cure. Acetic acid can harm lead, and should never be used on leaded glass. Instead, "neutral cure" sealants should be used. These high-performance construction sealants are not sold in consumer supply stores.

The appropriate type of sealant depends on the materials to be bonded and on the desired appearance and longevity. When windows are to be restored, the contractor should explain what types of waterproofing and sealants are to be used, and how long they are expected to last. On large projects, a letter from the product manufacturer should be obtained that approves and warranties the proposed application of their product. When in doubt, a traditional linseed-oil based glazing putty is often best.

Leaded panels will generally outlast several generations of waterproofing. When the waterproofing has failed, the window should be removed from the opening and waterproofed on a bench. Leaded glass cannot be adequately waterproofed in place. Removing the windows will provide an opportunity to perform maintenance on the window surround and to secure the reinforcement. This is far less expensive than totally releading the window, which is typically required if maintenance is deferred. When waterproofing or sealants break down, many building owners attempt to resolve the problem by installing protective glazing, when the window only needs maintenance. Protective glazing is not an alternative to maintenance; in fact, it impedes maintenance if not installed properly and can accelerate the deterioration of the stained glass.

A very common-but extremely harmful-practice in the American stained glass industry is performing major window repairs in place. The practice is routine among churches where the cost of restoring large windows can be prohibitive. However, undertaking major repairs in place provides only a quick fix. A window cannot be properly repaired or restored in place if it is bulging or sagging far out of plane, if over 5% of the glass is broken, or if solder joints are failing. Unscrupulous glazers can introduce a great deal of stress into the glass by forcibly flattening the window in place and soldering on additional bracing. At a comfortable distance the window may look fine, but upon close inspection the stress cracks in the glass and broken solder joints become obvious. Windows subjected to this treatment will deteriorate rapidly, and complete, much more costly restoration will likely be necessary within a few years (while a proper repair can easily last two generations or more).

Major repairs to windows are sometimes part of a larger preservation project. In such cases, the risk of damaging the windows can be very great if their removal and reinstallation have not been carefully planned. When major building repairs are also to take place, the windows should be removed first to prevent damage during other work. Windows should be reinstalled as the next-to-last step in the larger project (followed by the painters or others working on the finishes surrounding the stained glass).

And glass should be protected whenever other work is undertaken on buildings--whether or not the windows are also to be repaired. External scaffolding, for example, erected for repointing or roofing projects, may offer vandals and thieves easy access to windows and, through them, to building interiors. Stained and leaded glass should always be well protected whenever chemical cleaners are used on the exterior of the building; some products, such as hydrofluoric-acid cleaners, will cause irreversible damage.

Repairs to Glass

Minor repairs, such as replacing a few isolated pieces of broken glass, can be performed in place. This work, typically called a "drop-in," "stop-in," or "open-lead" repair, entails cutting the came flange around the broken piece of glass at the solder joints, folding it back to repair or replace the old glass, and resoldering the joints. Repairing a zinc came window is not as easy. Zinc cames are too stiff to open up easily, so they must be cut open with a small hack saw and dismantled until the broken area is reached. The glass is then repaired or replaced and the window is reassembled. New cames can be patinated to harmonize with the originals--but only with difficulty. Repatination should never be attempted in place, since it is impossible to clean off harmful residues trapped under the came.

Original glass should be retained whenever possible, even though it may be damaged. Replacement glass that exactly or closely matches the original piece can be very difficult to find, and costly to make. An endless variety of glass colors and textures were produced, and given the delicate chemistry of glassmaking, even samples from the same run can be noticeably different. The traditional secrecy that shrouds the glassmaking trade to this very day, as well as environmental bans of historically popular ingredients such as lead and cobalt for deep blues and greens, further hinders accurate reproductions. Therefore, it is nearly always better to use an imperfect original piece of glass than to replace it (Figure 15). If the paint is failing on a prominent feature of a window, a coverplate of thin, clear glass can be painted and placed over the original. (The coverplates must be attached mechanically, rather than laminated, so that they can be removed later if necessary.) A reverse image of the fading feature should be painted on the backside of the coverplate in order to get the two painted images as close together as possible. With repetitive designs, stencils can be created to produce multiple duplicates.

Sometimes replacement is the only option. Fortunately, custom glass houses still exist, including the company that originally supplied much of the glass for Tiffany commissions. Stained and leaded glass has also experienced a resurgence in popularity, and American glassmakers have revived many types of historic glass.

When missing, shattered, or poorly matched glass from later repairs must be replaced, the new pieces should be scribed on the edge (under the came) with the date to prevent any confusion with original glass in the future.

Glass cracks will enlarge over time as the contacting edges grind against each other, whenever the window is subject to vibration, thermal expansion and contraction, and other forces such as building movement. Therefore, it is important to repair cracks across important features as soon as they are detected and while a clean break remains. Years ago, cracks were typically repaired with a "Dutchman" or "false lead" by simply splicing in a cover lead flange over a crack. Although this conceals the crack, it creates an even larger visual intrusion and provides no bond to the glass. Today, there are three primary options for repairing broken glass: copper foil, epoxy edge-gluing (Figure 16), and silicone edge-gluing. These techniques differ in strength, reversibility, and visual effect, and the appropriate repair must be selected on a case-by-case basis by a restoration specialist.

Copper Foiling: Copper foil has the longest history and, unless the glass is unstable, is generally the best option when a piece of glass has only one or two cracks. Copper foil is a thin tape that is applied along each side of the break, trimmed to a minimal width on the faces, and soldered. A copper wire can be soldered on where additional strength is required. However, copper foil repairs should not be used on unstable glass, since heat is required that can cause further damage. Copper foil produces a strong repair, is totally reversible, and has a negligible aesthetic impact (a 1/16" [1.6mm] wide line).

Epoxy Edge-Gluing: This technique produces a nearly invisible line and is often used on painted glass, particularly focal points of a window such as a face, or a portion of sky intended to be one continuous piece. Epoxy can even be tinted to match the glass. It is also used for infusing shattered glass or microscopic cracks caused by intense heat from a fire. Epoxy produces a very strong repair, but will deteriorate in sunlight and requires secondary glazing to protect it from UV degradation. Epoxy is the least reversible of the three techniques, and usually the most expensive.

Silicone Edge-Gluing: This repair method has the lowest strength and should be used when a flexible joint is desirable-if, for instance, the window will be under continuous stress. Silicone repairs are easily reversible, and can be removed with a razor blade-when they are done correctly, that is. Silicone edge-gluing is not the same as smearing silicone all over the glass. This unfortunate practice, seen throughout the country, is useless as a repair technique, and usually causes more damage than if the glass were left alone. Silicone is almost clear, but it refracts light differently from glass and is, thus, easily detectable. Silicone is not affected by temperature, humidity or UV light. Silicone repairs are typically the least expensive repair option.

Repairs to Structural Support Systems

Windows may have detached from the saddle bars and begun to sag, bulge, and bow extensively. This point varies from window to window. Generally, however, a window sagging or bulging more than 1½" (38mm) out of plane has reached the point where it should be removed from the opening to be flattened out. Under these conditions, it is essential to note if the support system or leading pattern has failed so it may be corrected before the window is reinstalled. The window must be allowed to flatten over a few weeks in a horizontal position. This will minimize stress on the solder joints and glass. A moderate weight and controlled heat will help coax the window back into its original plane. The process requires patience. Once the window has flattened, the original support system should be reattached and additional support added as necessary. It is crucial to consider the original design so the new support bars do not intrude on important window features. Sometimes small thin braces or "fins" can be manipulated to follow existing lead lines exactly. These give support, but are almost invisible. Flattening windows also provides a good opportunity to apply new waterproofing to help prevent further deterioration. Today, a wide variety of traditional and synthetic compounds are employed.

Windows should only be removed when they need to be flattened, waterproofed, reinforced, or releaded. Allow plenty of time for careful, thorough work. Large projects can take several months, especially if complete releading is necessary. Owners, consulting professionals, and construction managers must therefore ensure that vacant openings will be weathertight for an extended period-whether the openings are covered by plywood, acrylics, or polymer film. If desired, images of the window can be printed on adhesive film and applied to rigid plastic and installed in the openings as temporary facsimiles during studio restoration.

Rebuilding or releading a window is an expensive and involved process. The releading process requires that a window be disassembled before it can be reassembled (Figure 17). The glass pieces must be removed from the cames, the old cement must be cleaned from each piece of glass, and all the pieces must be rejoined precisely. At every step the process involves the risk of damaging the glass. Furthermore, exceptional studios had unique leading techniques, and thus the cames should not be replaced casually. Total releading should only be undertaken when necessary to avoid or slow the loss of historic fabric. (It is essential to request a copy of all window rubbings if the windows are to be completely releaded.)

Lead and zinc cames, however, are intended to be a sacrificial element of a glass unit assembly, as mortar is to brick and paint is to wood; came will break down long before glass and must ultimately be replaced; came typically lasts 75 to 200 years depending on the window's quality, design and environment. A common preservation conflict arises in releading historic windows: whether to retain historical accuracy by using the existing profile, or to use came with a stronger profile for greater longevity. The decision must be carefully weighed depending on the significance of the window, the contribution of the came profile to the overall design, and the severity of the deterioration caused by a thin or weak came. In most windows, the came profile is essentially lost in transmitted light, but occasionally shadow lines are important and should be reproduced. Furthermore, it is important to correct technical problems that arise from flimsy original came. Occasionally, a slightly heftier came may be the best solution to resolve weak panels that have not proven the test of time. Under these circumstances, the thicker lead came (even if only 1/64" [0.4mm]) will cause a re-leaded panel to swell slightly, and the frame or perimeter leads may have to be trimmed to fit the opening. (Trimming the glass should be the very last resort.) This would not be an appropriate solution in a museum-quality restoration or for a highly significant window.

Photographing Stained Glass

Historic stained glass windows, laylights and domes should be documented to help ensure the best-quality restoration in the event of vandalism, fire or other loss. Photographic documentation is also important for insurance and investigation purposes when vandalism or theft is involved. Given the highly photogenic nature of stained glass, photographs can also serve as artwork for guidebooks or other interpretive or publicity purposes; quality photographs can be especially worthwhile in fundraising efforts.

Photographing stained glass is both challenging and rewarding. Windows and domes lit by daylight can seem to be ever changing in visual appearance. They can appear dramatically different in any given photograph depending not only on the photographic equipment and settings used, but also on the time of day, degree of cloud cover, the ambient interior light, and a multitude of other factors. Moreover, photographs may differ depending on the aspect to be captured. Painted flesh areas and highly translucent Prairie School windows often "burn out" if photographed in bright sunlight, while faceted jewels and very dense or plated opalescent glass often look best in direct sunlight.

Generally, exposures should be bracketed to capture the full range of the stained glass; the variation in images can permit different images to serve different purposes. Under most circumstances, interior lights should be turned off, and the stained glass should be photographed in both transmitted light (no flash) and reflected light utilizing a flash. The flash should ideally be positioned away from the camera to provide a raking light and to avoid reflected "hot spots." Although photographing with a flash will neutralize the transmitted light and black out the glass, it reveals the location and condition of the lead cames, braces, tie-wires, and other structural elements.

A tripod should be employed for a sharp image whenever using long exposures and higher apertures. The subject should be shot as level as possible to minimize the distortion known as "parallax." Occasionally, when shooting a group of windows, it is beneficial to develop a cardboard, Ecuboard, Masonite or similar cutout material to mask the window being photographed. Adjacent windows or windows on the opposite side of the room may need to be shaded or blocked to avoid "front lighting" on the window from competing with the transmitted light. Windows should also be photographed from the outside if there is no protective glazing to interfere with the view. This is particularly important with opalescent glass, which often was intended to be read from the exterior as well as the interior.

Some glass projects warrant a visual representation of the stained glass window to be in place during restoration. After establishing the existing window dimensions, a photograph of the stained glass window can be enlarged to full scale and copied on adhesive-backed transparent film. In essence a decal, it can then be applied to acrylic or polycarbonate sheets and used as a temporary replacement to fill the opening (above). Such film decals are sensitive to light and will not last indefinitely. However, they are reasonably convincing from a distance and can last a year or longer while the actual window is being restored.

The use of protective glazing (also known as secondary or storm glazing) is controversial. Potential benefits of protective glazing are that it can shield windows from wind pressure; increase energy savings; protect against environmental pollutants and UV light; provide vandalism and security protection, and reduce window maintenance. Potential drawbacks are that it can promote condensation; cause heat to build up in the air space and thereby increase the window's expansion/contraction; eliminate natural ventilation; reduce access for maintenance; offer a poor energy payback for the cost, and significantly mar the building's appearance. Protective glazing is often presented as a cheaper alternative to full-scale restoration. And all too often protective glazing is installed as a routine matter when there is little threat of damage from vandalism or other causes. Protective glazing, especially when improperly installed, may hasten deterioration of stained glass windows.

Various types of metal grills or screens are also used. They add security and vandalism protection but also impair the appearance of the window (inside and out) by creating new shadows that telegraph on the stained glass or diffusing transmitted light. As a general rule, protective layers should not be added on historic buildings unless the glass setting was designed for storm glazing. In most cases the potential drawbacks outweigh the potential benefits.

Under some circumstances, however, protective glazing or screens may be necessary. (This applies to windows. Domes and ceilings present a special case. See "Domes and Ceilings"). A real vandalism or security threat warrants protective glazing, such as when the windows can be reached easily or are in an isolated location. Protective glazing is also warranted when employed historically on a particular window as original plating (Tiffany Studios, for example, often used plate glass to keep dirt and moisture out of their multi-plated windows). Unusual circumstances (such as when the windows are painted on the outside) may also dictate the use of protective glazing. Finally, protective glazing is warranted when a UV filter is needed to prevent epoxy glass repairs from breaking down.

A variety of protective glazing materials are available. They include polycarbonates, acrylics, laminated glass, plate glass, and tempered glass. The plastic products are very strong, lightweight, and relatively easy to install, but will scratch, haze, and yellow over time, despite UV inhibitors. They also have a high coefficient of expansion and contraction, so the frames must be designed to accommodate change induced by temperature fluctuations. Poor installations in restrictive frames cause distorted reflections from bowing panels often damaging the historic frame. Protective panels of glass are heavier and more difficult to install, making them more expensive than plastic. However, glass will not bow, scratch, or haze and is usually the best option in aesthetic terms; laminated glass provides additional impact resistance.

A common error in installing protective glazing is to create a new window configuration (Figure 18). Insensitive installations that disregard the original tracery destroy the window's aesthetics-and the building's. When protective glazing is added, it should be ventilated. If a window is not ventilated, heat and condensation may build up in the air space between the ornamental glass and the protective glazing (creating a "greenhouse effect").

When absolutely necessary, protective glazing should be installed in an independent frame between ⅝" (16mm) and 1" (25mm) from the leaded glass. This allows the protective panel to be removed for periodic maintenance of both the historic window and the new glazing. The conditions of the air space between the two layers should be monitored on a regular basis; condensation should never collect on the window.

No ideal formulas have been developed for venting the air space between the ornamental glass and the protective glazing, but it is typically vented to the outside (unless the building is air conditioned most of the year). Generally, a gap of several inches is left at the top and bottom when glass is used, or holes are drilled in the protective glazing at the top and bottom when polycarbonates and acrylics are used. Small screens or vents should be added to keep out insects. Finally, it is important to realize that most original plating was "rough plate" or "ribbed" and never had a modern polished reflection. Some glass tinted the transmitted light intentionally, as originally designed: in this case any new or replacement plating should simulate this effect to respect the artisan's intention.

Domes and Ceilings

Stained glass domes and ceilings were very popular throughout the Victorian and Classical Revival periods. They are often principal interior features of churches, hotels, restaurants, railway stations, and civic buildings. The loss or unsympathetic alteration of leaded glass ceilings and domes is a widespread problem. Poorly planned rehabilitation projects sometimes cause the unnecessary removal or alteration of overhead leaded glass in order to comply with fire codes or to achieve perceived energy savings; occasionally, they are even concealed above suspended ceilings.

Moreover, stained glass in the horizontal position readily collects dust and dirt over the years and is relatively inaccessible for cleaning. It is also more likely to "creep" or slump when the reinforcement is inadequate. Most importantly, leaded glass cannot be sufficiently weatherproofed in a horizontal (or arched) position. It must always be protected by skylights or "diffusers"-rooftop features that diffuse the natural daylight into the attic or light shaft, and protect the leaded glass ceiling or dome from the elements (a).

Due to the inferior quality of glazing sealants of the late 19th and early 20th centuries, and to deferred maintenance, glass ceilings have frequently been removed or covered with roofing materials. Artificial lighting is then required to backlight the ceiling or dome, which robs the stained glass of its life−the vibrant effects created by ever-changing natural light. All types of artificial lighting can be found from floodlamps to fluorescent tubes. Outside sensors are even used to modulate the light level in an attempt to simulate changes in daylight. However, daylight is impossible to emulate. Moreover, it's free. Artificial lighting requires maintenance, introduces an additional fire hazard in the attic, increases the building's electrical load, and is supplied only at a financial and environmental cost.

Stained glass ceilings and domes that have been sealed off from natural light should be investigated for restoration. Once natural light is restored and the stained glass is cleaned, the lighting effect on an interior can be extraordinary. Improved skylight designs and major advances in glazing sealants since World War II (particularly silicones) encourage the restoration of skylights without the fear of inheriting a maintenance nightmare (b).

Much of the Nation's stained glass and leaded glass has recently passed, or is quickly approaching, its 100th anniversary-yet much of this glass has not been cleaned or repaired since the day it was installed. With proper care, the stained and leaded windows, transoms, and other elements that add so much to historic buildings can easily last another century.

Acknowledgements

Neal A. Vogel is the Principal of Restoric, LLC, Evanston, Illinois. Rolf Achilles is an Art Historian and Curator of the Smith Museum of Stained Glass Windows at Navy Pier, Chicago. All drawings and photographs by Neal A. Vogel unless otherwise stated.

Michael J. Auer, Technical Preservation Services, National Park Service, served as technical editor. Additional assistance was provided by Charles Fisher, Anne E. Grimmer, and former staff Chad Randl, Technical Preservation Services.

The authors would like to thank the following for sharing information and providing opportunities to review works in progress: Botti Studios of Architectural Arts, Evanston, IL; Chicago Metallic Corporation, Chicago, IL; Chicago Art Glass and Jewels, Inc., Cedar Grove, WI; Conrad Schmitt Studios, Inc., New Berlin, WI; Cypress Lawn Memorial Park, Colma, CA; Hollander Glass, Stanton, CA; Mary Clerkin Higgins, New York, NY; Venturella Studios, New York, NY; Wardell Art Glass, Aurora, IL. Special thanks for providing editorial assistance to Arthur J. Femenella, Femenella & Associates, Branchburg, NJ; Richard L. Hoover, Stained Glass Association of America, Lee's Summit, MO; and H. Weber Wilson, Oltz-Wilson Antiques, Portsmouth, RI.

This publication has been prepared pursuant to the National Preservation Act of 1966, as amended, which directs the Secretary of the Interior to develop and make available information concerning historic properties. Comments about this publication should be addressed to: Charles Fisher, Technical Publications Program Manager, Technical Preservation Services-2255, National Park Service, 1849 C Street, NW, Washington, D.C. 20240. This publication is not copyrighted and can be reproduced without penalty. Normal procedures for credit to the authors and the National Park Service should be provided. The photographs used in this publication may not be used to illustrate other publications without permission of the owners.

October 2007

Duthie, Arthur Louis. Decorative Glass Processes: Cutting, Etching, Staining, and Other Traditional Techniques. New York: The Corning Museum of Glass and Dover Publications, 1982.

Fisher, Charles E., III, ed. The Window Handbook: Successful Strategies for Rehabilitating Windows in Historic Buildings. Washington, D.C.: National Park Service and Georgia Institute of Technology. 1986. Rev. 1990.

Fisher, Charles E., III, Deborah Slaton, and Rebecca A. Shiffer, eds. Window Rehabilitation Guide for Historic Buildings. Washington, D.C.: Historic Preservation Education Foundation/National Park Service, 1997.

Heinz, Thomas A. Lloyd Wright Glass Art. Academy Editions, Ernst & Sohn, 1994.

Heinz, Thomas A. "Use & Repair of Zinc Cames in Art-Glass Windows." Old House Journal, (September/October 1989), pp. 35-38.

Lee, Lawrence, George Seddon and Francis Stephans. Stained Glass. New York: Crown Publishers, 1976.

Lloyd, John Gilbert. Stained Glass in America. Jenkintown, PA: Foundation Books, 1963.

Stained Glass Association of America. SGAA Reference & Technical Manual, Second Edition Lee's Summit, MO: The Stained Glass Association of America, 1992.

Wilson, H. Weber. Great Glass in American Architecture: Decorative Windows and Doors Before 1920. New York: E. P. Dutton, 1986.

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The Preservation and Repair of Historic Stained and Leaded Glass

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PRESERVATION BRIEFS Glass is a highly versatile medium. In its molten state, it can be spun, blown, rolled, cast in any shape, and given any color. Once cooled, it can be polished, beveled, chipped, etched, engraved, or painted. Of all the decorative effects possible with glass, however, none is more impressive than "stained glass."

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a brief history of rubber : The University of Akron

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a brief history of rubber : The University of Akron

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a brief history of rubber : The University of Akron

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K-12 Lesson Plans: In this social studies lesson plan, students will explore the development of rubber and its use in society. They will research the history of rubber and will construct a timeline to display key events and the progression of rubber's use in society.

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What Is Electroplating and How Does It Work?

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What Is Electroplating and How Does It Work?

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Electrochemistry is a process by which very thin layers of a selected metal are bonded to the surface of another metal at the molecular level. The process itself involves creating an electrolytic cell: a device that uses electricity to deliver molecules to a particular location.

How Electroplating Works

Electroplating is the application of electrolytic cells in which a thin layer of metal is deposited onto an electrically conductive surface. A cell consists of two electrodes (conductors), usually made of metal, which are held apart from one another. The electrodes are immersed in an electrolyte (a solution).

When an electric current is turned on, positive ions in the electrolyte move to the negatively charged electrode, called the cathode. Positive ions are atoms with one electron too few. When they reach the cathode, they combine with electrons and lose their positive charge.

At the same time, negatively charged ions move to the positive electrode, called the anode. Negatively charged ions are atoms with one electron too many. When they reach the positive anode, they transfer their electrons to it and lose their negative charge.

The Anode and Cathode

In one form of electroplating, the metal to be plated is located at the anode of the circuit, with the item to be plated located at the cathode. Both the anode and cathode are immersed in a solution that contains a dissolved metal salt-such as an ion of the metal being plated-and other ions that act to permit the flow of electricity through the circuit.

Direct current is supplied to the anode, oxidizing its metal atoms and dissolving them in the electrolyte solution. The dissolved metal ions are reduced at the cathode, plating the metal onto the item. The current through the circuit is such that the rate at which the anode is dissolved is equal to the rate at which the cathode is plated.

Purpose of Electroplating

There are several reasons why you might want to coat a conductive surface with metal. Silver plating and gold plating of jewelry or silverware typically are performed to improve the appearance and value of the items. Chromium plating improves the appearance of objects and also improves its wear. Zinc or tin coatings may be applied to confer corrosion resistance. Sometimes, electroplating is performed simply to increase the thickness of an item.

Electroplating Example

A simple example of the electroplating process is the electroplating of copper in which the metal to be plated (copper) is used as the anode, and the electrolyte solution contains the ion of the metal to be plated (Cu ²⁺ in this example). Copper goes into solution at the anode as it is plated at the cathode. A constant concentration of Cu ²⁺ is maintained in the electrolyte solution surrounding the electrodes:

Common Electroplating Processes

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What Is Electroplating and How Does It Work?

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Electrochemistry is a process by which very thin layers of a selected metal are bonded to the surface of another metal at the molecular level. The process itself involves creating an electrolytic cell: a device that uses electricity to deliver molecules to a particular location.

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Photograph by Daici Ano / Flickr

Earlier this year, Dan Doctoroff, the C.E.O. of Sidewalk Labs, Google's sibling company under Alphabet, answered a question about what his company "actually does" during a Reddit "Ask Me Anything" session, replying, "The short answer is: We want to build the first truly 21st-century city." Quayside, a Toronto neighborhood the company is developing in partnership with a Canadian tri-government agency, is the first step toward Doctoroff's goal. It has been in the news because it could inspire a Black Mirror plot: It will be built from "the Internet up," according to a project document, a merger of "physical and digital realms." Fittingly, according to the New York Times, "No obvious way to opt out of Quayside's surveillance systems exists, except by staying out of the area."

But Quayside's newsworthy for another, more encouraging reason: The plan is to build the place, not out of concrete and steel, but wood-and wood is looking good. A recent advance in wood technology should interest the neighborhood's developers: Teng Li, a University of Maryland mechanical engineer, created with his colleagues wood that's as "strong as steel, but six times lighter," he said. Liangbing Hu, Li's co-author on the study, added, "This kind of wood could be used in cars, airplanes, buildings-any application where steel is used." Making it is just a two-step process. The scientists first boiled natural wood in a mixture of sodium hydroxide and sodium sulfite, to remove some of the lignin and hemicellulose, substances contained in the walls of wood cells (the former retard parasite and bacterial attacks, the latter cover and bind fibers). Then they put the wood in a hot press, which leads, as they say in the paper, "to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres." The result, they conclude, is a "low-cost, high-performance, lightweight alternative" to "most structural metals and alloys."

"Our proposal is that we need timber to save us."

The idea of future wood cities has been hanging around for at least a few years. In 2014, for example, the Boston Globe wondered, "Will cities of the future be built of wood?" The rise of both human population and global temperature prompted much of the interest in the sustainability of city-scale timber construction. By 2050, we will number almost 10 billion; and since two-thirds of us will be city dwelling-up from just over half in 2014-cities will have to grow. It'd be ideal to do that without curtailing efforts to combat climate change; it wouldn't be helpful, for instance, to keep extracting and transporting the raw materials needed to build steel and concrete structures, which are more expensive and have large carbon footprints. Wood, on the other hand, is "a plentiful resource that grows back relatively quickly, and even pulls carbon out of the atmosphere as it does," the Globe noted. Yugon Kim, an architect passionate about timber construction, said, "We all are hard-wired to see the city as being steel, glass, and concrete. Our proposal is that we need timber to save us."

The proposal hasn't been ignored. The Economist published a video titled, "Wooden skyscrapers could be the future for cities." The main obstacle to this outcome-what a 2016 paper called "a full timber building renaissance"-is the public's fear of city fires, which has been reflected over centuries in construction codes globally. Some researchers, like Alastair Bartlett, at the University of Edinburgh, see in these obstacles an "opportunity," as he wrote in a 2017 study, "to revisit compartment fire behaviour and to quantify the impact of these new construction technologies on the compartment fire dynamics."

Bartlett, along with some colleagues, tested the sort of wood mid- and high-rise buildings-like Framework, in Portland-have recently been made out of, known in the industry as "cross-laminated" or "mass" or "tall" timber, which is how Quayside's developers refer to it. Bartlett set up three rooms of equal size, about as big as a large walk-in closet. Two of the rooms had two exposed surfaces of timber (one with two walls exposed, the other a wall and the ceiling); the last room had two walls and the ceiling exposed (non-exposed surfaces were covered with plasterboard). Each room had four wooden "cribs," or pallets, for the "fuel load," placed on the ground, one of which was lit using fiber strips soaked in paraffin. Bartlett then documented how fast and how hot each room burned. The room with an exposed wall and ceiling managed to "auto-extinct"-the fire went out by itself. This depended "on the char layer [of the wood] remaining attached" rather than falling off while the cribs were burning, Bartlett concluded. He wants to do many more experiments because it's still not clear how, in mass timber buildings, to get compartment fires to reliably burn out on their own, a "cornerstone of fire safety engineering design," he writes. "The failure modes of common compartment construction systems and materials are relatively poorly documented from a scientific (rather than compliance testing) perspective."

Photograph by Rory M.Hadden, Alastair I.Bartlett, et al.

The combustibility of this wood depends partly on its size, according to Daniel Safarik, editor of the Council on Tall Buildings and Urban Habitat, a Chicago-based non-profit. "Massive wood walls and structural beams and columns comprised of engineered panels have demonstrated fire performance equal to concrete and, in some cases, superior to steel," he told The Architect's Newspaper. "Mass timber has to burn through many layers before it is structurally compromised-basically it 'chars' long before it collapses." Still, as a 2016 review concluded, "Large-scale and full-frame tests are also necessary...to determine the variety of possible fire induced failure modes that may occur in real mass timber buildings." The same will no doubt be true of the new densified wood Li and his colleagues recently created.

There is also, alongside the environmental and economic, an aesthetic-psychological case for wood cities. Clare Farrow, who is co-curating a current London exhibit called "Timber Rising-Vertical Visions for the Cities of Tomorrow," wrote in Dezeen, "Studies are showing that the presence, scent and touch of wood can have remarkably positive effects, not only on people's wellbeing in a general sense, but more specifically on stress levels, blood pressure, communication, learning and healing." A 2015 review in Wood Science and Technology supports her claims and also suggests that "specific aspects of wood such as colour, quantity, and grain pattern should be examined" in future studies.

I certainly have a fondness for wood. On work errands with my father, when I was a child, I remember being drawn to the plywood section of Home Depot. I'd run my hands against the surfaces of large slabs, sometimes still damp after being cut, and I'd smell the fresh sawdust piled up at the cutting station. I still have my 7th and 8th grade woodshop projects-gumball machine, foldable stool-and for some reason, to my wife's chagrin, love making my apartment's wood floor creak. Recently, I was bummed to learn that, last year, a plan to build a 10-story timber condo in New York City was scrapped ("the cooling-off of NYC's condo market," according to the website Curbed, "made the deal seem less attractive.") But Quayside's wood-centric vision of future cities has me feeling optimistic. "Timber construction is possible at all scales and at pioneering height," a Quayside document states. We'll have to see if that confidence catches on, in Newark and beyond.

Brian Gallagher is the editor of Facts So Romantic, the Nautilus blog. Follow him on Twitter @brianga11agher.

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WATCH: The difference between a great ancient building and a modern one. This classic Facts So Romantic post was originally published in February 2018.

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The Case for Making Cities Out of Wood - Facts So Romantic - Nautilus

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Earlier this year, Dan Doctoroff, the C.E.O. of Sidewalk Labs, Google's sibling company under Alphabet, answered a question about what his company "actually does" during a Reddit "Ask Me Anything" session, replying, "The short answer is: We want to build the first truly 21st-century city."

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ChemMatters - December 2016 - Page 14-15

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ChemMatters - December 2016 - Page 14-15

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OU MAY NOT SEE THEM, BUT

they are all around you. Called rare-
earth elements, 17 silvery metals
are in nearly every high-tech prod-
uct that is a part of our modern lives. Smart-
phones and some baseball bats are stronger
and lighter because they contain an element
called scandium. The green color of a foot-
ball field on a television screen is created by
another little-known element called terbium.

Batteries that power windmills, cars, and electric guitars use neodymium, lanthanum, and other rare-earth elements.

If you could see them, it would be tough to tell rare-earth metals apart. Most were discovered in minerals unearthed from the same little town in Sweden, and they look and act so much alike chemically that it took a century to separate them from one another. But each rare-earth element has its own atomic number. These atomic numbers are: 21 (scandium), 39 (yttrium), and 57-71

(a series of elements, called the lanthanides,

usually listed in their own row in a periodic table of the elements; see sidebar). Also, because they strengthen other metals, they are essential in building smaller and lighter high-tech products.

High-tech applications

Rare-earth elements have been called "chemical vitamins," because as little as 0.2% of these special metals, alloyed with other materials, can affect glass, metal, and electronic products in ways that no other element can. Some are used in night-vision goggles and sunglass lenses, while others assist in producing lasers, screen displays, the world's strongest magnets, and even ear buds.

In the 1970s, color television was the first
technological invention to explore the optical
properties of rare-earth elements. Scien-
tists found that when materials containing
europium and yttrium were coated onto
television tubes, they would generate a clear,
Other compounds of europium and were combined to create vivid green
and blue colors and a striking white light,
making television as vivid as movies. Com-
binations of these three luminescent colors
make the whole light spectrum (which is dif-
ferent from the pigment spectrum of paints
and crayons) possible. Today, these "technol-
ogy metals" are used in flat-screen televisions
and in the display panels of smartphones and
tablets.

Rare-earth elements are also found in sports equipment. Bicycles and baseball bats, golf clubs, and hockey sticks sometimes take advantage of an alloy made of scandium and aluminum to get more power from less weight. An alloy is a mixture of metals or a mixture of a metal and another element. The scandium-aluminum alloy is made by incorporating nanoparticles-particles that are less than 100 nanometers and contain atoms SHU

TTE RS TO CK

14 ChemMatters | DECEMBER 2016/JANUAR Y 2017 www.acs.org/chemmatters

By Gail Kay Haines

Y

drawer_subscribe

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OU MAY NOT SEE THEM, BUT they are all around you. Called rare-earth elements, 17 silvery metalsare in nearly every high-tech prod-uct that is a part of our modern lives. Smart-phones and some baseball bats are strongerand lighter because they contain an elementcalled scandium.

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Plastics Chemistry: The Science of Plastics | Plastics Make It Possible

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Plastics Chemistry: The Science of Plastics | Plastics Make It Possible

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Ever wonder how chemicals become plastics?

It's magic.

Kidding ... Actually, it's science in action. Specifically, chemistry. Plastics are the result of the very real marriage of raw materials, engineering, and energy-all brought together through chemistry.

Here's a brief introduction to how chemists make modern plastics possible. No worries if you didn't ace your chemistry class. While plastics can be high tech, advanced materials, understanding their basic construction is easy. Well, at least for me ...

Plastics Chemistry: How Plastic are Made

To make today's plastics, chemists start with various elements (atoms such as carbon, hydrogen, oxygen and so on) derived from natural resources. Remember that magnificent, elegant periodic table of chemical elements that lists the building blocks of everything on earth? That's the list of ingredients.

Chemists combine various atoms to make molecules, which are simply two or more atoms held together by chemical bonds. When making plastics, these molecules generally are called monomers. These monomers then are combined by chemical bonds into a chain or a network-this is called polymerization. And the resulting materials are called polymers. Or plastics.

(As you see, chemical bonds are rather important-and not simply to enable modern plastics. They also organize all those elements that combine to make up everything in the universe-including we humans. Without chemical bonds, life would simply be a chaotic maelstrom of elements. Not much of a life, actually...)

Read More: When was plastic invented?

The Science of Plastics: Thermoplastics and Thermosets

If the monomers join together lined up like a chain (picture a string of pearls), the polymer is called a thermoplastic. This plastic behaves sort of like an ice cube: it melts when heated and solidifies when cooled ... like water, over and over again. Polypropylene (the stuff butter tubs often are made of) is an example of a thermoplastic.

If the monomers connect in a three-dimensional network, the polymer is called a thermoset. This plastic behaves sort of like an egg: once it sets and "cures" (or in the egg's case, once it's cooked), it cannot return to its gooey, liquid state. An epoxy from the hardware store that hardens and cures when applied is an example of a thermoset.

Because thermosets are a three dimensional network of monomers, they can be very tough. For example, your car tires are made with thermoset plastics (often called synthetic rubber).

Thermoplastics are tough, too, but they often are used in less intense settings, such as lightweight bottles for soft drinks that are not subject to massive heat and friction like tires.

Read More: Polyethylene density

Plastics Chemistry: Always Evolving

Chemists (along with other smart people) over time have come up with many ways to combine ingredients to make new polymers ... and even to combine polymers. The molecules can be fashioned with various properties depending on what we need: sticky or slippery or lightweight or soft or hard or foamy or stretchy or ... well, you get the point. That's why plastics are used in so many helpful everyday products, from spatulas to car bumpers and from medical implants to fabrics for clothing.

And this is only the beginning, as chemists are constantly developing innovative new plastics-to help make aircraft lighter, hearts pump longer, food stay fresher, homes more energy efficient and so on.

Thus ends the chemistry lesson. See, that was easy.

Further Reading: Biodegradable Plastics

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Plastics Chemistry: The Science of Plastics

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Ever wonder how chemicals become plastics? It's magic. Kidding ... Actually, it's science in action. Specifically, chemistry. Plastics are the result of the very real marriage of raw materials, engineering, and energy-all brought together through chemistry. Here's a brief introduction to how chemists make modern plastics possible.

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Stained glass: history and technique (article) | Khan Academy

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Stained glass: history and technique (article) | Khan Academy

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Stained glass: history and technique (article) | Khan Academy

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If you're seeing this message, it means we're having trouble loading external resources on our website.

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How are LEGO Duplo bricks made? | The Kid Should See This

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How are LEGO Duplo bricks made? | The Kid Should See This

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Not long ago I joined the awesome LEGO video team at the DUPLO factory in Hungary. I was there to host a video for LEGO's social channels but they kindly let me vlog snippets as we toured around!

In the video above, Maddie Moate shows and tells how LEGO Duplo bricks and characters are made -almost five million bricks a day. She's filmed how tiny granules of plastic travel through tubes to be mixed with color pellets. The pieces are then quickly molded and cooled in a plastic injection molding machine, printed with faces color by color, and assembled by machines.

And here's the video she made with LEGO:

Secrets of the LEGO DUPLO factory
Our bricks even get a lick test at the LEGO DUPLO factory in Hungary - watch how we make almost five million of them a day ?

Posted by LEGO on Friday, February 1, 2019

Watch more videos from Maddie Moate on this site, travel to Denmark to see how robots and machines make LEGO at their Billund factory, or fly by drone over LEGO House, Denmark's new LEGO visitor center.

Plus, a LEGO + math video: How many LEGO combinations can be made with 6 standard bricks?

Also excellent: A fascinating video primer on Plastic Injection Molding and more videos about plastic.

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How are LEGO Duplo bricks made? | The Kid Should See This

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Not long ago I joined the awesome LEGO video team at the DUPLO factory in Hungary. I was there to host a video for LEGO's social channels but they kindly let me vlog snippets as we toured around! In the video above, Maddie Moate shows and tells how LEGO Duplo bricks and characters are made -almost five million bricks a day.

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Growing copper crystals | Chem13 News Magazine | University of Waterloo

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Growing copper crystals | Chem13 News Magazine | University of Waterloo

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Roads create a grid-like pattern on the landscape in a remote section of Argentina's Mendoza Province. This area has an arid climate and receives anywhere from 4 to 20 inches (100-500 mm) of precipitation per year. These conditions cause much of the soil to be dry and reddish, as shown in this Overview.

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Investing and Trading Metals Commodities

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Investing and Trading Metals Commodities

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Use these resources to get reliable information about investing in gold, precious metals and commodities, and find out about suppliers, standards, and trends in the metals world.

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Want to know why giant ships can float, how your earbuds make music, what graphene is, or how windows can clean themselves? You've come to the right place! Here you'll find simple explanations you can really understand-hurrah!

Hard stuff... made simple!

Explain that Stuff is an online book written by science writer Chris Woodford (author of many popular science books for adults and children). It includes over 400 easy-to-understand articles, richly illustrated with over 4000 photos, artworks, and animations, covering how things work, cutting-edge science, cool gadgets, and computers. We take the "pain" from explain and the "tough" out of stuff! There's more information on this website than in your average expensive science book, it's continually updated, and it's completely free to use! Explain that Stuff also helps to support curriculum learning (conventional STEM education and home-schooling).

How to use this site

There are five simple ways to find what you want:

1. A-Z index: Browse articles by name.

2. Timeline: Find inventions by date.

3. Random: Discover something new.

4. Search: Use the search engine.

5. Teaching guide: Browse study topics.

What's hot in October 2023?

Our simple introductions explain the science behind the headlines. In the news now...

What's new?

Some of our latest articles...

From atoms and cells to nuclear power plants and the human brain, the scope of science is truly amazing. But what exactly is the scientific method... and why is it still our best hope for making sense of the world?

Most popular

These are some more of our classic, ever-popular articles:

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The articles on our site are divided up into broad topical areas, listed below. We've also given you a rough idea of the kind of questions you're going to find answers to in each section:

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In the ~17 years we've been online (2006-2023), pages from this site have been viewed over 140 million times in total. Our articles have been cited by dozens of books and over 2000 academic papers and patents. We've received over 4000 user feedback forms in the last decade and 92% gave us four or five stars out of five-a weighted average of 4.6-but there's always plenty of room to do better. We hope you find this site useful too!

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Articles from this website are registered at the US Copyright Office. Copying or otherwise using registered works without permission, removing this or other copyright notices, and/or infringing related rights could make you liable to severe civil or criminal penalties.

Text on this website is copyright © Chris Woodford with copyright dates as noted in each individual article. All rights reserved. Full copyright notice and terms of use.

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Explain that stuff! Science and technology made simple

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A collection of FREE, easy-to-understand science, technology, and how-it-works articles for the whole family!

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The Online Hub for Corrosion Professionals

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The Online Hub for Corrosion Professionals. Learn more about CUI, surface prep, coatings and other topics in the corrosion industry.

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2018 Ceramic 3D Printer Guide - All About Ceramic 3D Printing | All3DP

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2018 Ceramic 3D Printer Guide - All About Ceramic 3D Printing | All3DP

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Italian 3D printer manufacturer WASP is known for its large size delta 3D printers. They made headlines by using their Big Delta systems to build houses and shelters in developing countries.

Originally, WASP only offered a LDM professional clay extruder system. It can be used with all of their printers, but also with third-party 3D printers. When properly set up, this technology offers some of the most precise paste extrusion ceramic 3D printing on the market.

If you're interested, WASP's Clay Extruder Kit 2.0 will set you back US$700 (around €650). It comes with a 5 kg tank with a stand, a n extrusion piston, pressure reducer, a cochlea with an interchangeable pressure chamber, a high couple stepper engine and 10 kg of porcelain.

However, WASP has recognized that some users prefer a clay 3D printer that works out of the box. You can choose between two sizes. The Delta WASP 2040 Clay offers a build volume of Ø200 ✕ 400 mm. This printer will already set you back $3000.

Its big brother, the Delta WASP 40100 Clay, boasts a build volume of Ø400mm ✕ 1000mm. The manufacturer has not published the price of this machine, instead, you need to ask for a quote. Both machines offer a maximum layer resolution of 0.5mm and print at a maximum speed of 150 mm/s putting them in the same league as the Ceramo One.

Advantages: Among the most notable innovations presented by the new ceramics extruder is the extrusion system itself. It eliminates air bubbles out of the mixture, has an extrusion controlling system with a retraction option and an outward pressure multiplier of up to 40 bar.

Ideal ceramic 3D printer for: This technology offers some of the most precise paste extrusion 3D printing on the market. The green objects are very fragile at first and need to be sintered in a kiln, but the results are quite impressive, and the costs are relatively low.

Ceramic 3D printer types: The Clay extruder kit is used in combination with most WASP's 3D printers and turns them into ceramic 3D printers. If you want to retrofit another Delta 3D printer model with it, contact WASP before ordering. Both the Delta WASP 2040 Clay and the Delta WASP 40100 Clay offer hassle-free ceramic 3D printing out of the box.

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2018 Ceramic 3D Printer Guide - All About Ceramic 3D Printing | All3DP

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Italian 3D printer manufacturer WASP is known for its large size delta 3D printers. They made headlines by using their Big Delta systems to build houses and shelters in developing countries. Originally, WASP only offered a LDM professional clay extruder system. It can be used with all of their printers, but also with third-party 3D printers.

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Plastic Injection Molding | The Kid Should See This

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Plastic Injection Molding | The Kid Should See This

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Bill [Hammack] details the key engineering principles underlying plastic injection molding. He describes its history and then reveals the intricate details of the process. He shows viewers where to found, on any injection-molding product, the markings created by injection molding. He closes with a description of the one of the finest examples of the injection molding: the Lego brick.

After watching this Engineer Guy video, study a few LEGO pieces for the injection point and ejector pin witness marks. Then check out this How It's Made video:

Follow this with Inside the LEGO Factory: How robots & machines make LEGO. Plus: Ocean Confetti, the challenge of micro-plastics and the 16 year old that turned banana peels into a biodegradable bioplastic.

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Plastic Injection Molding | The Kid Should See This

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Bill [Hammack] details the key engineering principles underlying plastic injection molding. He describes its history and then reveals the intricate details of the process. He shows viewers where to found, on any injection-molding product, the markings created by injection molding. He closes with a description of the one of the finest examples of the injection molding: the Lego brick.

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Metal Stamping Tool Kit - Metal Stamping Supplies - Punches &...

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Metal Stamping Tool Kit - Metal Stamping Supplies - Punches &...

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Metal Stamping Tool Kit - A value-priced kit of all the essential tools for stamping letters and designs onto metal. Includes the following: Bench Block 4" x 4" (100-081) Brass Hand Brush (

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The Berkeley Pit – Butte, Montana - Atlas Obscura

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The Berkeley Pit – Butte, Montana - Atlas Obscura

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Copper from this former open-pit mine helped to electrify America. Now it is filled with more than 40 billion gallons of acidic water, heavy metals, and unique microscopic lifeforms.

The Berkeley Pit is a former open-pit copper mine in Butte Montana, and now one of the only places in the world where you can pay to see toxic waste; admission is two dollars. The sheer scale of the site is something to behold. In aerial photos, it appears simply as a huge black splotch.

The pit is one mile long by half a mile wide, and over 1780 feet deep, 1000 of which are filled with acidic water with high concentrations of heavy metals and toxic chemicals, including copper, iron, arsenic, cadmium, zinc, and sulfuric acid. The iron-rich water near the surface is reddish, yielding to a vibrant lime-green hue not far below the surface, where copper concentrations are higher. If you were to drink large amounts of this lovely concoction it would kill you by corroding through your digestive system.

The waste water is so saturated with copper that Montana Resources Inc., which operates the nearby Continental open-pit copper mine, is able to "mine" copper directly from the water. Berkeley Pit water, 13 million gallons per day, is pumped from the deeper, copper-rich part of the lake to nearby scrap iron holding ponds, causing the copper and iron to swap places. The resulting copper sludge yields up to 400,000 pounds of copper in one month. The now iron-rich water is pumped back into the Berkeley Pit, creating the waterfall seen on the northeastern rim.

In November 1995, a flock of migrating snow geese landed on the Berkeley Pit Lake. After several days of stormy weather and fog that prevented the birds from leaving, 342 were found dead. Initially, BP-ARCO and Montana Resources, the responsible parties for the Pit under federal Superfund law, denied that the toxic water had anything to do with the death of the geese, attributing the deaths to a previously acquired infection. These findings were disputed by the State of Montana on the basis of its own lab tests, which determined that excessive exposure to Pit water had corroded the birds' esophagi. Since that time, the Pit has a 24-hour bird-watch program to prevent birds from landing in the water for more than a few hours.

Birds are not the only thing the State of Montana has to be concerned about. The water level in the Pit is constantly rising. The rate of rise has slowed in recent years to roughly one foot per month. As of December 2009, the water level in the Berkeley Pit was 5,284.98 feet above sea level. At 5,410, the "critical water level", the Pit water would contaminate the nearby ground water of the Butte valley, home to more than 30,000 people. Through ground water flows, such contamination could potentially spread down the Clark Fork River, the largest drainage in western Montana; the mines of Butte sit at the headwaters. The community already pumps in drinking water from surrounding highland reservoirs and the Big Hole River, 20 miles away over the Continental Divide, because historic mining operations contaminated the valley aquifer.

A water treatment plant was built in 2003 to prevent the Berkeley Pit water from ever reaching that critical level. The plant, which is visible next to the waterfall on the northeast rim of the Pit, will begin to pump and treat Pit water before it would reach the critical level, currently projected around 2023. Treated Pit water will then either be used in Montana Resources nearby mining operations, or discharged to Silver Bow Creek, the primary headwater creek of the Clark Fork River. Currently, the plant is used to capture and treat surface water flowing from the north of the Pit, thus slowing the rate of rise.

Interestingly enough, new fungal and bacterial species have been found to have adapted to the harsh conditions inside the Pit. Intense competition for the limited resources caused these species to evolve the production of highly toxic compounds to improve survivability, some of which have been isolated from these organisms and show selective activity against cancer cell lines. Currently research continues.

The Berkeley pit was in operation from 1955 - when several underground mines were combined to create it - until 1982. Over that time, it swallowed several historic Butte neighborhoods. In 1982, ARCO shut down operations and turned off the underground pumps that had previously dewatered the mines beneath the Butte Hill, leading to the Pit lake we see today. Over the active lifespan of the mine approximately 320 million tons of ore and over 700 million tons of waste rock were mined from the Pit. In other words, it produced enough copper to pave a four-lane highway two inches thick from Chicago to New York, with enough left over to keep going to the tip of Long Island.
We explored the Berkeley Pit Mine on Obscura Day - March 20th, 2010. Photos, stories and more here

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Copper from this former open-pit mine helped to electrify America. Now it is filled with more than 40 billion gallons of acidic water, heavy metals, and unique microscopic lifeforms. The Berkeley Pit is a former open-pit copper mine in Butte Montana, and now one of the only places in the world where you can pay to see toxic waste; admission is two dollars.

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PitWatch.org is the Web version of PitWatch, published periodically by the Berkeley Pit Public Education Committee for the purpose of educating Butte residents,

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The Science of How Copper Forms Patina

Copper home furnishings provide an elegant beauty because copper is a "living" metal, meaning it changes color over time. The beauty of copper is unique among decorative materials because the changes it undergoes are unique to each home and location.

The natural changes that happen to copper objects make them a one-of-a-kind symbol of heritage that 's hard to replicate. The shades of patina that form on the surface of a copper furnishing can store the memories of meals, spills, new homes and life changes over the course of centuries.

Copper is more than a shiny metal - it is one that can be adorned with beautiful carvings that tell a story. Knowing how copper patina forms will give you a deeper appreciation for the unique patina that appears in your family's history. This knowledge will also allow you to influence what color of patina forms, and how fast it will do so.

The Chemical Reaction

Ever ask yourself, "Why does copper turn green?" The formation of patina on copper is similar to the formation of rust on iron. Both happen when oxygen in the air interacts with the metal atoms in the presence of water.

Copper reacts with oxygen that is in the air, resulting in copper dioxide (Equation 1). The copper dioxide then reacts with more oxygen to form copper oxide (Equation 2). This copper oxide from reaction 2 is the main culprit that will later form the colors of the patina. If sulfur is present on the surface of the copper, then the two can react to form copper sulfide, which is black (Equation 3). The greenish and blueish colors of copper's patina come from the next set of reactions.

Air contains more than just the oxygen that we breathe. It contains carbon dioxide, which we breathe out, along with water vapor.

The first reaction that gives patina its color is when one molecule of carbon dioxide and one molecule of water, both in the air, react with two molecules of copper oxide on the surface of the copper. The result is a compound called malachite (Equation 4), which varies in color from shades of dark green to shades of blue.

The second reaction that adds to patina's color is when three molecules of copper oxide from Equation 2 can react with two molecules of carbon dioxide and one molecule of water (Equation 5). The result is azurite, which is a compound that varies in color from shades of blue to shades of purple.

The third reaction that influences the color of patina is when four molecules of copper oxide from Equation 2 reacts with one sulfate molecule and three water molecules (Equation 6). The result is a compound called brochantite, which varies in color from shades of dark green to emerald.

The chemical reactions described above can be written in atomic symbols as follows:

Equation 1: 4Cu + O2 → 2Cu2O [red to pink]

Equation 2: 2Cu2O + O2 → 4CuO [black]

Equation 3: Cu + S → CuS [black]

Equation 4: 2CuO + CO2 + H2O → Cu2CO3(OH)2 ["malachite," dark green to blue]

Equation 5: 3CuO + 2CO2 + H2O → Cu3(CO3)2(OH)2 ["azurite," blue to purple]

Equation 6: 4CuO + SO3 + 3H2O → Cu4SO4(OH)6 ["brochantite," dark green to emerald]

Reasons Why Patina Can Be Green and Blue

Patina has different colors and patterns that depend on the unique experience that each copper object has had. The next section explains the physics and chemistry of why the colors of patina can vary so much from place to place and from time to time. This section describes in broad terms why the presence of certain chemical compounds can affect the green and blue hues often seen in patina.

The products that result from Equations 4-6 in the previous section each has their own shades of color:

Malachite: dark green to blue

Azurite: blue to purple

Brochantite: dark green to emerald

Depending on what combination of these three is present, the color of the patina can vary from shades of green to shades of blue. Darker greens indicate an abundance of malachite and brochantite, while blues suggest that azurite is abundant. Each of these three compounds can form beautiful crystalline structures on their own, like precious rocks. When mixed in small amounts and held on the surface of copper, these three compounds produce the pleasant luster of patina.

It is interesting to note that human blood is red because the molecule that carries oxygen in our blood is iron, which produces a red color. Shellfish, such as crabs, have greenish-blue blood because the metal atom that carries oxygen in their bodies is copper.

Factors That Affect Patina Formation

Why does copper patina over time? As we have established, patina forms on copper because of chemical reactions. The faster a chemical reaction is, the more products will form. Several factors in the copper and the surrounding environment can affect how fast patina forms, and what colors it will have.

Knowing these factors will not only help you appreciate the patina on your copper but will also allow you to influence how the patina forms. This knowledge will surely impress your friends and relatives as they marvel at the elegance of your copper and the sophistication it brings to both your home and your conversations.

Temperature

Chemical reactions happen when molecules move and collide with each other. The molecules are too small to see with the naked eye, but we know that chemical reactions happen thanks to a variety of signs, such as a change in color. Heat causes molecules to move faster, whether those molecules are bouncing around in the air or a liquid. Higher temperatures cause more reactions to happen at the surface of the copper.

The higher the temperature, the faster chemical reactions can occur. Faster-moving molecules move with more energy, so their collisions with each other are more likely to break connections within a molecule. More than that, high-energy collisions help to form bonds between two molecules. This is similar to how it is easier to dissolve sugar in hot tea than it is to do so in iced tea. Ever wonder why the sugar always sits at the bottom of your iced tea, even though you have been stirring it for five minutes?

- Geographic Location: Different regions have different climates. Inland and desert areas can be very hot, while coastal regions are cold. Regions at high elevations are colder than valleys. Often the location where you keep your copper products determines the temperatures that your copper is exposed to.

- Room Ventilation: Rooms without windows and ventilation can become very hot during the summer.

- Nearby Sources of Heat: Stoves, fireplaces, furnaces, heaters and refrigerators produce heat. This heat can warm up the entire room or nearby copper objects.

Humidity & Precipitation

The chemical reactions that form patina require the presence of water. Water exists in the form of moisture in the air, mist, rain, and snow.

- Geographic Location: Some places have high humidity, meaning there is a lot of moisture in the air. Some regions have both high temperatures and high humidity, which promotes the chemical reactions that form the patina. Some regions are very dry, so there is minimal natural water vapor in the air.

- Precipitation Rate: Different regions receive different amounts of rain and snow. Copper objects exposed to wet weather are frequently drenched or moist. Some regions have rain for most of the year, while others receive only a few weeks of rain per year.

- Nearby Sources of Steam: Household appliances can produce steam, which moistens the air. Kettles, water boilers, and pressure cookers release significant amounts of steam that can affect nearby copper objects or ones in the same room.

Impurities in the Copper

Copper ore taken from the ground has many impurities in it. Through the process of electrolysis, pure copper is obtained. However, copper can contain impurities in the form of other metals, such as iron, nickel, cobalt and molybdenum. These impurities can also react with oxygen and water vapor, just like copper does, to form compounds that have color.

Iron can form iron oxides that have a reddish brown color. Cobalt can form cobalt oxides that have a greenish-brown color. The amount of impurities in the copper can affect the color of the patina.

Air Pollution

In Equation 6 above, copper oxide reacts with sulfur oxide and water to form brochantite, which gives a greenish color to patina. Sulfur exists in the atmosphere in the form of sulfur oxide. One source of sulfur oxide air pollution is through burning fossil fuels, such as oil and gasoline. In fact, acidic rain that damages buildings and statues gets its acidity in part from the sulfur oxides that mix with water vapor to form sulfuric acid.

- Geographic Location: Urban areas that have many automobiles will have high amounts of sulfur oxides in the atmosphere. Other sources of sulfur oxide production in the air are industrial regions that release smoke, such as power plants and chemical production plants.

Types of Patina Available at CopperSmith

At CopperSmith, we do not boast about our excellent selection of beautiful patinas without good reason. We have a range of patina colors to choose from, so you should have no problem finding the right shade that matches your home décor. You do not have to wait years or decades to have the right shade of patina. We provide matured patinas that you can enjoy immediately.

Shades of patina available at CopperSmith include:

Natural Raw Copper [reddish pink]

Old Coin [reddish brown]

Antique [dull brown]

Dark Antique [dark brown]

Bronze [dark blue]

Not only do we understand the nuances of different shades of copper patina, but we also add an extra layer of beauty to copper furnishes that the patina itself cannot achieve: texture. The physical texture of the copper gives depth to, and brings the character out of, the patina.

Textures of copper patina available at CopperSmith include:

Smooth

Hood hammered

Beehive hammered

Light hammered

Hand hammered

The beauty of copper patina has yet another dimension of depth and elegance that is unique. Just as the hammered texture of copper changes how light reflects off its surface, three-dimensional carvings captivate the imagination by suggesting hidden stories behind each curve. Ornate carvings can imbue a copper item with a charming nature. Alternatively, they can add a dash of regal pride to an otherwise mundane household fixture.

Custom-designed carvings in CopperSmith products include:

Landscapes

Gardens

Royal emblems

Geometrical patterns

Birds

Fish

Bricks

Types of Copper Furnishing Available at CopperSmith

CopperSmith has copper furnishings for every room in the house: kitchens, bathrooms, dining rooms, bedrooms and even the garage. Browse our website to see all the different copper products that we offer.

- Range Hoods: Range hoods above the stove can easily become the centerpiece of the kitchen. Copper patina has a presence that will inevitably draw attention from all corners of the room. Decorate your range hood with straps and rivets that themselves can have textured patterns. Not only do range hoods serve the important safety function of removing fumes and particulate matter from the air, but they can also be a pleasure to the eyes.

- Sinks: Aside from the stove, the kitchen sink is a quintessential piece of furnishing in the kitchen. CopperSmith has apron sinks and barn sinks that display a face towards the kitchen that draws attention from across the room. Sinks are not just found in the kitchen but are also in the bathroom. Garages can have sinks next to the washer or for everyday use, so even that room can be enhanced by copper. Some people prefer to have copper sinks next to their outdoor grill or in their patio, making food preparation and clean up easier.

- Tubs: Copper bathtubs have a unique feel of luxury and character. Not only do they have elegant designs, but they are easy to clean, as well.

- Tabletops: Copper tabletops are versatile pieces of furniture that can go into any room in the house, whether as a dining table, coffee table or nightstand.

- Examples of other copper items at CopperSmith include:

Light Fixture

Mirrors

Knobs & Pulls

Towel Bars & Rings

Backsplash Murals

Tapestry Hangers

And more!

How to Create Your Desired Patina

Since we know the chemical reactions that cause the different shades of color in copper patina, there are ways that we can affect what color patina becomes and how fast patina forms. Creating artificial patina is a common activity among people who make copper jewelry and kitchenware. The following tips will teach you how to patina copper.

Making a consistent pattern of artificial patina on large furnishings such as bathtubs, tables and range hoods is more challenging than doing it on jewelry. For large objects, it is best to pick a piece of copper whose patina was industrially created by professionals.

For each of the following methods, the longer the copper is exposed to the homemade concoction of chemicals, the more intense the patina will become. You should be sure to test out the strength of your treatment on small objects such as coins and pennies before doing it on your prized copper possessions.

Keep notes about how much of each chemical was mixed, which will allow you to adjust the strength or effect of your home-made patination mixture for your desired effect. Test the method to see how fast the patina forms, so you know when to stop the incubation time.

Make sure you pay attention to safety procedures about handling any home cleaning agent. An adult should supervise children under 18. Household cleaning agents can cause irritation in the eyes, skin, nasal passage and lungs. They can also be dangerous if ingested.

Incubate with Hot Crushed Boiled Eggs

The hot boiled egg method is perfect for creating a brownish patina on copper. Eggs are hard boiled and then crushed to pieces in a re-sealable plastic bag or container while they are still hot. The copper is then placed into the bag and sealed for minutes to hours, depending on the desired shade of brown patina. The longer the incubation time, the darker the brown color. This method is ideal for small copper items, but large ones are difficult to manage through this technique.

Use Miracle-Gro

Miracle-Gro plant fertilizer is an excellent oxidizer of copper. For a blue patina, mix one part Miracle-Gro with three parts water for a solution that you can spray or wipe onto the copper. For a green patina, mix one part Miracle-Gro with three parts red wine vinegar. A patina will form within 30 minutes and become permanent within 24 hours.

Soaking in White Vinegar and Salt, Sawdust or Potato Chips

Soaking copper in white vinegar and salt will create a blue or green patina. Other ways of doing this are to bury the copper in sawdust or crushed potato chips soaked in white vinegar. The longer the copper is buried, the darker the patina becomes.

Expose Copper to Saltwater and Ammonia Vapors

Spray the copper with a solution of salt water and then place the copper in a container that contains non-detergent ammonia. The copper should not be touching the ammonia liquid, but should be raised above it.

The sealed container will trap ammonia vapors that will then make contact with the copper. Be careful when handling ammonia: wear protective gloves, wear safety goggles and be near water in case you need to rinse ammonia off of yourself. Also, do not sniff ammonia and use ammonia outdoors or make sure the room is well-ventilated.

How to Naturally Influence the Color of Patina

There are ways to allow the patina to form naturally without applying chemicals to it. Exposing the copper to outdoor conditions will help patina to form. Outdoor conditions include fog, rain, snow, and heat. Leaving the windows open will change the temperature and moisture content of the room, so any copper objects in that room will also experience the changes.

You can purposely leave copper furnishings next to sources of heat and moisture, such as in the kitchen next to the stove or the back of the refrigerator. Leaving copper next to a window so that it receives lots of sunlight will expose the copper to natural heat.

Sealing the Patina to Keep Your Desired Color

The patina that forms from artificial methods can be easily brushed off, so it must be sealed to be kept permanent. Sealants can be wax, lacquer or a proprietary mixture of chemicals. Jewelry-making and craft stores carry multiple brands of sealants for protecting patina.

Since patina forms through chemical reactions between copper and molecules in the air, preventing the air from reaching the copper will stop any more patina from forming. Applying a sealant can also be a way to keep the patina that you like, preventing it from changing further.

Get Advice on Including Copper Furnishings to Your Home Décor

The experts at CopperSmith are waiting to provide expert advice on how to design the copper furnishings that are perfectly unique to your home and needs. We stand behind our money-back guarantee because we believe in delivering only the best service and products. We can send you samples of our copper patinas so that you can know the exact look and feel of our copper for yourself.

Our expert designers will walk you through the process and options, taking the guesswork out of the shopping and planning process. Our knowledge and experience make it easy for you to get the right furnishing that will have the right fit for every location and purpose.

Why wait any longer? Contact us, and we will put the shine in your day!

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Copper home furnishings provide an elegant beauty because copper is a "living" metal, meaning it changes color over time. The beauty of copper is unique among decorative materials because the changes it undergoes are unique to each home and location. The natural changes that happen to copper objects make them a one-of-a-kind symbol of heritage that 's hard to replicate.

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raku firing techniques glazes recipes raku glaze formulas spectrum

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Learn about common Raku firing techniques, Raku glazes, recipes and formulas.

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Innovations: Introduction to Copper: Mining & Extraction

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Innovations: Introduction to Copper: Mining & Extraction

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Copper Applications in Metallurgy of Copper & Copper Alloys

By Vin Calcutt

The Copper Age | The Bronze Age | The Middle Ages and Later | Mining

Copper minerals and ores are found in both igneous and sedimentary rocks. Mining of copper ores is carried out using one of two methods.

Underground mining is achieved by sinking shafts to the appropriate levels and then driving horizontal tunnels, called adits, to reach the ore. Underground mining is, however, relatively expensive and is generally limited to rich ores. El Teniente, in Chile, is the world's largest underground copper mine.

Open pit mining is employed when the orebodies are extensive, low in grade, and relatively near the surface, where they can be quarried after removal of overburden. Chile also boasts the world's largest (in terms of output) open-pit copper mine, Escondida. The largest copper mine in North America (and the world's largest man-made excavation) is the Bingham Canyon Mine near Salt Lake City, Utah. A $1.5 billion modernization program completed in 1998 turned Bingham Canyon into North America's lowest-cost copper producer, a model of operational efficiency and environmental compliance.

Copper is found in the earth's crust and the oceans although the amount in the latter is thought to be negligible, amounting to no more than about eight months mine production at present-day rates. The upper 10 kilometers of the crust is thought to contain an average of about 33 ppm of copper. For commercial exploitation, copper deposits generally need to be in excess of 0.5% copper, and preferably over 2%. The known reserves of higher-grade ore in the world amount to nearly 1 billion tons of copper. At the present rate of mine production, which is about 13.9 million tons (12.5 million metric tons) a year, known reserves of copper could be depleted in about 65 years. However, successful exploration for new mineral deposits, technological advances in mining and extractive metallurgy (which enable the exploitation of leaner ores, thereby enlarging the pool of known reserves) and copper uses (which permit copper to be used more sparingly where larger quantities were used in the past) and the continued recycling of scrap are likely to forestall indefinitely depletion of this valuable metal.

For example, in the first mile depth of the crust of the continents, it is estimated that there is 3x 10 ¹⁸ metric tons of copper diffusely distributed. The relatively concentrated portion of this copper is only a small fraction of the whole, constituting an estimated 10 ¹⁰ metric tons in deposits with a grade of 0.25% or more. At current world mine production, this represents a million years' supply of copper theoretically available in the mineable portion of the earth's crust.

Table 4 shows some of the most common copper minerals. Some of these have long had a value in their own right, such as malachite, prized for its unusual and pleasing appearance and used for millennia in jewelry and ornaments.

The barren rock, or gangue has to be separated from the sulfide minerals in order to smelt the metallic copper from the ore. By far the greatest proportion of copper is extracted from the sulfides of copper, iron and sometimes other metals. Such ores originate from sulfur-bearing volcanic magmas, which have separated into metal sulfides and siliceous melts. The copper has concentrated almost entirely into the sulfide fraction, and if this becomes separated from the siliceous melt it can become deposited in veins or in fissures in the host rock by hydrothermal or other geological activity. In many ores (and most of those found in the Western USA) the copper minerals occur as a dispersion of fine particles. Such ores are called porphyries. Where mineralized rocks become outcropped or shattered, the sulfide minerals undergo chemical changes due to air, groundwater and heat, giving rise to the other main variety of copper minerals - the oxidized ores.

There is no shortage of copper resources. In fact, copper is one of the most abundant of the metallic elements in the earth's crust. The average estimated concentration is between 55 and 70 mg/kg, placing it below chromium (200 mg/kg) and zinc (132) but above tin and lead. Commercially exploited deposits of copper ores are found in many parts of the world, frequently associated with mountain-building processes. Deposits occur at many locations in the western cordillera of the Americas, mainly in the United States and Chile, and in areas of the North American plains like Michigan, Ontario, Quebec and Manitoba, at sites associated with the Pre-Cambrian shield. Copper is also found in many other countries throughout the world. Perú, Poland, México, Zaire, Zambia and Papua-New Guinea have historically been among the leading producers, and although African production has fallen sharply in recent years owing to political difficulties, large untapped resources remain. In addition, huge quantities of copper are known to exist as "deep-sea nodules" scattered on the ocean floor, although high recovery costs has thus far prevented their commercial exploitation. Chile and the USA are, respectively, the world's two leading copper-producing nations, Chile having overtaken the USA in the early 1990s.

Extraction
Ores are first mechanically crushed and ground so that nearly all copper mineral particles are freed from the gangue. Flotation by the injection of air and violent agitation is carried out with the pulverized ore held in suspension in water, to which surface-active agents have been added. The process yields concentrates containing roughly 30% copper, which are sequentially fed to a smelter, a furnace in which most of the some iron and sulfur are removed, then to a converter or converting furnace, where most of the remaining iron and other impurities are removed. (Depending on the type of smelting and converting furnace used, as much as 99+% of the sulfur can be recovered. It is used to make sulfuric acid, which is sold or used to leach copper from suitable ores directly, thereby circumventing the entire smelting-converting cycle.) The result is an impure (98+%) form of metal known as blister copper (for its surface appearance). The blister is then fire-refined further to adjust its sulfur and oxygen contents, yielding metal that is sufficiently pure for many other-than-electrical uses. However, since the fire-refined metal may contain commercially viable concentrations of precious metals (mostly silver and gold), most of it is cast into thick sheets known as anodes that are sent to the large electrolytic cells, where final refining takes place. A dc electric current, passed through the cells, dissolves the anodes and deposits the copper on cathodes. The final product of the refining process is electrolytic tough pitch (ETP) copper normally containing between 99.94 and 99.96% Cu. Cathodes are re-melted under controlled conditions and cast into forms suitable for further processing.

Modern methods of extraction allow economic leaching and electro-winning of copper from low-grade ores and extraction techniques are continuously being refined and developed to achieve the most efficient removal of copper from a wide variety of ores from sources around the globe. The techniques for extraction of copper from oxidized ores are quite different from those employed for the sulfide ores. The oxidized ores, consisting of the silicates, carbonates and sulfates, are treated by several methods, all involving some form of leaching of the crushed ore with sulfuric acid to produce impure solutions of copper sulfate. Today, more than 13% of all "new" copper is produced from leachates, which are normally concentrated using solvent extraction (SX) and stripped of their copper content by conventional electrowinning (EW), the so-called SXEW process. Sulfide ores are not efficiently attacked by sulfuric acid, but they can be leached if first oxidized by long exposure to the atmosphere and by contact with naturally occurring Thiobacillus Thiooxidans and Thiobacillus Ferrooxidans bacteria.

A simple infographic about the mining and extraction of copper was published in the November 1997 issue of Innovations.

The Copper Age

Pre-dynastic Egyptians knew copper very well. In hieroglyphic writing the symbol used to denote eternal life, the ankh, was also used to represent copper. The Greek philosophers later adopted the symbol, slightly modified, as . The connection between eternal durability and the lifetime cost-effectiveness of copper and its alloys is surely not coincidental!

The Egyptians obtained most of their copper from the Red Sea Hills, but copper predates ancient Egypt by several millennia, and it is now known that an older civilization based on the Euphrates also new copper and utilized well-developed smelting techniques. The earliest known artifacts made from smelted metal were copper, and excavations at Catal Huyuk near Konya in Southern Anatolia, have yielded slags derived from the smelting of copper that have been dated to as early as 7,000 BC. Other civilizations in the Near- and Middle East, Hindustan and China also developed the use of the vital metal.

The Greek author, Homer, referred to the metal as 'Chalkos'; the Copper Age is therefore referred to as the Chalcolithic Age. In Greek mythology, the goddess of love, Aphrodite, is said to have emerged out of the sea near Cyprus looking at her image in a copper mirror. Some historians hold that this shows that the oldest profession is therefore metallurgy. Roman writings refer to copper as 'aes Cyprium' since so much of the metal then came from Cyprus.

'Oetzti', the 5,000-year-old mummified man recently discovered high in the Alps on the Italian-Austrian border was found with many implements including an excellent arsenical copper axe. It seems that he was probably a coppersmith himself, since his hair had high concentrations of copper and arsenic, which could probably have come from no other source.

The Bronze Age

Before 3,000 BC it had been found that the addition of tin to copper produced bronze, an alloy that is harder and stronger than copper. Some of the earliest bronzes known come from excavations at Sumer, and are of considerable antiquity. At first, the co-smelting of ores of copper and tin would have been either accidental or the outcome of early experimentation to find out what kinds of rock were capable of being smelted.

Significant engineering uses had been found for copper as early as 2750 BC, when it was being used at Abusir in Egypt for piping water. (Some ancient Egyptian copper water tubes have survived to the present, a remarkable demonstration of the metal's durability.) Copper and bronze were employed for the making of mirrors by most of the Mediterranean civilizations of the Bronze Age period. The obliteration of Carthage by the Romans has obscured developments in Northern Africa at that time. It is only quite recently that evidence of the considerable engineering skills of the Carthaginians has emerged, including the earliest known use of gear wheels, cast in bronze. Bronze was used in many of the artifacts of every day Roman life - cutlery, needles, jewelry, containers, ornaments, coinage, knives, razors, tools, musical instruments and weapons of war. This pattern of use tended to be repeated wherever the smelting of bronze and copper was introduced, though necessarily on different time scales.

The Middle Ages and Later

The invention of printing increased the demand for copper because of the ease with which copper sheets could be engraved for use as printing plates to give accurate reproduction of illustrations and maps. In Germany, playing card designs were engraved on copper as far back as 1430. Copper plates have long been adopted as the best means of engraving maps. The first known maps printed from copper plates are two Italian editions, dated 1472, by the geographer Ptolemy.

Copper or bronze wire then became a very important product, being vital for the weaving industry. The use of copper for sheathing the hulls of wooden boats was developed initially to prevent attacks on the timbers in subtropical waters by the teredo worm but it was subsequently found that copper-clad hulls also resist marine biofouling. This useful property prevented the heavy drag caused by the growth of weed that limited the speed of ships. (It has been reported that Lord Nelson's victory at Trafalgar resulted in part from the speed of his copper-clad ships, which enabled him to outmaneuver his adversaries.) The demand for copper was significantly increased as a result.

However, by far the greatest extension in the use of copper resulted from Michael Faraday's discovery of electromagnetic induction in 1831 and the way that the effect could be used to generate electricity. The same principle was used to develop electric motors. The electric lamp was invented by Sir Joseph Swan in 1860 and brought to a commercial design by Thomas Edison in 1879. These 19 th century developments stimulated a tremendous demand for copper for generators, power cables, motors and all other products of the electrical engineering industry. Copper has the highest thermal and electrical conductivity per unit volume of any known substance except silver, which is only slightly superior in this respect. Because the conductivity of copper is dependent on its purity, extensive use is made of copper in its unalloyed form. Today about half of the world's production of copper is for electrical requirements.

Mining

The oldest methods for removing rock from underground mines were the sledgehammer and wedge and the equally ancient technique of fire setting. In the latter case a fire set up against a rock face would produce thermal expansion stresses - the rock would either crumble naturally or could be shattered by water quenching. It was some time after the Islamic world introduced blasting powders from China to Europe in the 13th Century that explosives were first used specifically for mining. Today the old mining techniques have been replaced almost entirely by blasting with safe modern explosives and the use of heavy-duty mechanical cutting equipment, where the rock is soft enough to merit such treatment.

Also in this Issue:

Archives:
2007 |2006 |2005 |2004 |2003 |2002 |2001 |2000 |1999 |1998 |1997

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Introduction to Copper: Mining & Extraction

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By Vin Calcutt The Copper Age | The Bronze Age | The Middle Ages and Later | Mining Copper minerals and ores are found in both igneous and sedimentary rocks. Mining of copper ores is carried out using one of two methods.

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The Corning Museum of Glass - One Museum Way - Corning, NY 14830 800.732.6845 or 607.937.5371 © 2002 - Corning Museum of Glass. All Rights Reserved. Privacy Policy | Terms of Use

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Polyvinyl Alcohol Slime - Gelfand Center - Carnegie Mellon University

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Polyvinyl Alcohol Slime - Gelfand Center - Carnegie Mellon University

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In this experiment, a polymer (polyvinyl alcohol) chemically reacts with borax to form a crosslinked polymer network. Individual polymer chains are formed by covalent bonds, which are strong bonds. In making slime, the individual polymer chains are bound together by weak hydrogen bonds. The resulting polymer network is composed of strands of polyvinyl alcohol held together side-by-side by the borate molecules. It is evident that this crosslinking is weak because of the ease with which the slime flows and pulls apart. However, even though this crosslinking is weak, it does alter the properties of the resulting polymer.

Toy stores carry the materials needed for this experiment in kits (look for "slime" or "goop"), or the final product can be purchased as Gak™. The slime mixture is non-toxic, but the borax and PVOH can be irritating to the eyes, so use safety glasses and wash hands at the end of the experiment. The slime may stain clothing and carpeting, so care should be exercised. The slime should be discarded in the trash and NOT down the drain, as it may clog the drainpipe. It tends to dry out if left exposed to the air, so store it in a sealed plastic bag.

Supplies needed:

Polyvinyl alcohol solution (instructions for preparation included below)

Borax solution (instructions for preparation included below)

Small (3 oz) cup

Plastic teaspoon

Wooden stick

Waxed paper

Procedure:

1. Measure 2 tsp. of polyvinyl alcohol polymer solution into a cup.
2. Add 1/4 teaspoon of Borax solution. Mix well with a wooden stick.

3. Touch and try to pour the product. How does it feel? Can it be poured?

4. Working on waxed paper, roll the "slime" into a ball and try to bounce it. Does it bounce? If desired, add talcum powder to the slime ball to decrease its stickiness.

5. Let it sit for a while. What happens to it?

6. Try to pull it apart quickly. Next try to pull it apart very slowly. Try to cut the slime with a spoon. How does it behave? Is it a liquid or a solid? Support your answer with observations.

The slime product behaves sometimes as a liquid and in other cases as a solid. Such behavior is called "viscoelasticity" and materials are said to be "viscoelastic". Liquids can be poured and solids maintain their shape. How does this material compare as a solid and/or a liquid?

There are a number of variations that can be made to this experiment. By adding 1 teaspoon of talcum powder or cornstarch to the polyvinyl alcohol in the first step, the polymer properties can be changed. The talcum powder or cornstarch act as "filler" and result in a very different product and behavior. In industry, fillers such as talc and carbon black are added to crosslinked polymers to adjust and vary properties such as color and strength. Filler also reduces the cost of the product since the filler materials are generally inexpensive.

The addition of glitter or confetti to the polymer solution makes a very attractive slime!

Put your slime in the refrigerator or freezer to cool it below room temperature. Be sure it is in a plastic bag or wrapped in plastic wrap so it won't dry out. How do the properties of the polymer change with temperature? Do plastics behave differently outdoors in freezing weather compared to indoors at room temperature?

For a more elaborate experiment, have different groups of students use different amounts of sodium borate. For example, divide students into 5 groups. Have one group add 2 ml of borax to 100 ml of PVOH solution. The others groups should add 4, 8, 12, and 20 ml of borax to the 100 ml of polymer solution, respectively. This should more easily demonstrate the effects of crosslinking on the properties of the polymer. Using more sodium borate results in more crosslinking. Students can stretch or roll the slime into long ropes and determine which slime (which amount of crosslinking) is best for this.

For high school chemistry classes, refer to the article Casassa, E.Z., Sarquis, A.M., Van Dyke, C.H., J. Chem. Ed., 63, 57, 1986, for details about the chemistry of polyvinyl alcohol slime.

PREPARATION OF SOLUTIONS FOR THIS EXPERIMENT:
4% Polyvinyl Alcohol (PVOH) Solution

Dissolve 40 grams of PVOH powder (molecular weight of ~100,000, Polysciences, Inc.) in 900 ml of distilled water.

Heat gently for several hours until dissolved (solution turns clear). Make sure the solution does not boil, or the properties will be altered.

Dilute to 1 liter with more water.

The prepared solution should be clear and somewhat viscous. It stores well in the refrigerator until needed.

A 4% PVOH solution is also available from Flinn Scientific.

4% Sodium Borate, Na2B4O7 * 10 H2O, Solution

Dissolve 10 grams of sodium borate in 250 ml of distilled water. You can obtain Borax at the grocery store near the laundry detergent.

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Polyvinyl Alcohol Slime - Gelfand Center - Carnegie Mellon University

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In this experiment, a polymer (polyvinyl alcohol) chemically reacts with borax to form a crosslinked polymer network. Individual polymer chains are formed by covalent bonds, which are strong bonds. In making slime, the individual polymer chains are bound together by weak hydrogen bonds.

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Aerogels are the perfect gift for the geek/hacker/tinkerer/technology enthusiast in your life. Here are some fun gift ideas:

Valentine Aerogel (as featured on Wired)

Pink, heart-shaped Valentine Aerogels are a unique and fascinating gift for space enthusiasts and general nerds alike! Comprised of 95% air by volume and made of the same kind of aerogel used by NASA on the Mars rovers, these aerogels have been infused with optically active materials to afford their unusual light-variant color properties! Since introducing them Valentine's Day 2013, we've barely been able to keep them in stock (thanks in part to Wired, DVICE, and many others). Get yours now in time for the holidays!

Aeroeggs

Aerogel Fun for Only $10

Experience the magic of nanotechnology with hydrophobic (waterproof) aerogel particles! Not only do our aerogel particles give you an inexpensive way to experience the famous "blue" aerogel first-hand, but enables you to plunge your hands into a tank of water without ever getting wet (watch the video below).

Bottled Skies

Bottled Skies from aerogel artist Iannis Michalou(di)s (the only artist we know with parentheses in his name) are a beautiful showpiece that captures the magic of the ethereal visual properties of aerogels in a unique handcrafted piece. And the name Bottled Sky is apt-silica aerogels are blue for the same reason the sky is blue (Rayleigh scattering), meaning these works are about as close to an actual "bottle of sky" as you can get! Available in two different variations.

Hydrophobic Silica Aerogel Disc

For those who want to get their hands on their own little piece of the space program, we recommend Hydrophobic Aerogel Discs. Over 96% air by volume, these aerogels have been made waterproof and are resistant to fingerprints, moisture, and can even float in a glass of water without damage! Not to mention they're super cool looking too.

A Gift for the Pyro in Your Life for Only $30 (as seen on Penn and Teller Tell a Lie)

Perhaps you've heard about the amazing ability of aerogels ability to protect Hershey's Kisses, crayons, flowers, and the like from the flame of a blowtorch. While you could use an incredibly delicate aerogel tile (see below), we recommend Pyrogel XT flexible aerogel blankets. Unlike classic silica aerogel tiles, Pyrogel XT is flexible, cuttable, and resists the flame of a blowtorch for hours on end with no risk of cracking, making it perfect for science projects, demos, and saving scientists from flamethrowers.

Buy Pyrogel XT Now Buy Classic Silica Aerogel Tile Now

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Aerogels are the perfect gift for the geek/hacker/tinkerer/technology enthusiast in your life. Here are some fun gift ideas: Valentine Aerogel (as featured on Wired) Pink, heart-shaped Valentine Aerogels are a unique and fascinating gift for space enthusiasts and general nerds alike!

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METALS Introduction to MATERIAL SCIENCE HONORS. - ppt download

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METALS Introduction to MATERIAL SCIENCE HONORS. - ppt download

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metals introduction to material science honors.

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METALS Introduction to MATERIAL SCIENCE HONORS. - ppt download

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Jim Briscoe on REEsLiberty Star Uranium & Metals Corp

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Jim Briscoe on REEsLiberty Star Uranium & Metals Corp

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Jim Briscoe on REEsLiberty Star Uranium & Metals Corp

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Because the logistics are very good at Hay Mountain (two paved roads and nearly flat level terrain and mild weather), we believe that if an economically minable body of REEs is delimited that it can be mined at low cost, concentrated, and that concentrate can be shipped to the brand new metallurgical facility at Mountain Pass for separation into different REE metals in a saleable form.

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What's Happening Inside Those 4th of July Fireworks | World Science Festival

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What's Happening Inside Those 4th of July Fireworks | World Science Festival

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What's Happening Inside Those 4th of July Fireworks | World Science Festival

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Fireworks have come a long way since they were first invented in ancient China. As early as 200 BC, people had found that they could create loud bangs by throwing bamboo shoots into a fire; when heated, the air pockets inside the plant expand rapidly and the bamboo explodes with a violent crack.

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Fireworks colors are a matter of chemistry. The colors come partly from the elements and compounds used in fireworks and partly by incandescence or light produced by different temperatures. Here's a look at how fireworks colors work:

Firework Colors - Luminescence of Element and Compounds

When chemicals are heated, the ions emit characteristic wavelengths or colors of light. This works much like the flame test, a method used to identify a substance by its color in a flame. Metal ions are responsible for common colors:

Red

strontium salts, lithium salts
lithium carbonate, Li ₂CO ₃ = red
strontium carbonate, SrCO ₃ = bright red

Orange

calcium salts
calcium chloride, CaCl ₂
calcium sulfate, CaSO ₄·xH ₂ O, where x = 0,2,3,5

Gold

incandescence of iron (with carbon), charcoal, or lampblack

Electric White

white-hot metal, such as magnesium or aluminum
barium oxide, BaO

Green

barium compounds + chlorine producer
barium chloride, BaCl⁺ is bright green

Blue

copper compounds + chlorine producer
copper acetoarsenite (Paris Green), Cu ₃As ₂O ₃Cu(C ₂H ₃O ₂) ₂ = blue
copper (I) chloride, CuCl = turquoise blue

Purple

mixture of strontium (red) and copper (blue) compounds

Silver

burning aluminum, titanium, or magnesium powder or flakes

Quality control is important in all aspects of fireworks design, including color formulation. Impurities and contaminants in the chemicals can completely ruin the effect. For example, even trace amounts of sodium in a chemical mixture will produce a bright yellow color that can drown out weaker colors.

Firework Colors - Incandescence

You know how a stove burner is dark when its relatively cool, red when its hot, and white-hot when you turn it all the way up? This is incandescence of the heating element, which is light emitted by the element as it gets hot. Fireworks also rely on incandescence for special effects and colors. Certain chemicals are red, orange, yellow, and white when heated. In particular, metals are heated to produce colored sparks, glitter, and fountain effects. Titanium, iron, and aluminum flakes are common metals heated to incandescence in fireworks.

Firework Periodic Table

Here's a handy periodic table you can print that shows the principal elements used in fireworks. The table is color-coded, so you can see at a glance which colors are produced by heating certain elements.

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Fireworks colors are a matter of chemistry. The colors come partly from the elements and compounds used in fireworks and partly by incandescence or light produced by different temperatures. Here's a look at how fireworks colors work: When chemicals are heated, the ions emit characteristic wavelengths or colors of light.

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Types of Glass used in Stained Glass Work

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Types of Glass used in Stained Glass Work

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Read about and see all of the types of glass you can use in your stained glass work.

There are hundreds, probably thousands, of types of glass, with their different colors and textures, used in stained glass work. They all start out being one of the 2 basic types, cathedral or opalescent, then expand from there.

Cathedral glass is clear glass that you can see through. It comes in any color you could think of. It can have a texture on one side, or be smooth on both sides. It can be swirled or streaked with another color of cathedral glass.

Opalescent glass is glass that you can't see through. As with cathedral glass, opalescent glass comes in every color imaginable. It can have a texture on one side. It can be streaked or swirled with one or more colors of opalescent glass.

As you look through the examples below, you will see many variations of both cathedral and opalescent, some of them combining both types of glass in one single sheet of glass.

Each one of the types of glass you see below comes in a variety of colors, so don't think your only choice is the color shown.

At the end of this list I will give you the web site for each glass company so you can see all of the different types of glass each company makes.

Full Mouth Blown Antique applies to art glass produced by the historical mouth-blown cylinder method and relies on the craftsmanship of a master glassblower. The glass is blown into a cylinder shape which is annealed and cooled. The cylinder is then scored lengthwise, separated, re-heated and folded out into a flat sheet. Characteristics include attractive linear striations, and small round, sometime oval bubbles or seeds. These small bubbles (known as seeds) are one of the most important characteristics. Antique glass can be used in any piece you make. It makes beautiful flowers, nice backgrounds, entire panels. The only drawback is the price. It's expensive!

Drawn Antique, also called semi-antique, machine antique or new antique, is a simulated full-antique. The textural striations are mechanically applied in these types of glass. Quality is excellent and cost is less than full antique. GNA (German New Antique) is a common example. Drawn Antique makes nice backgrounds and borders. Actually, it can be used anywhere in a panel. Make sure you cut it with the striations all going in the same direction.

Baroque is an exclusive glass made by Spectrum. It is a machine made "reamy" glass, created by combining glasses of mis-matched compositions. The different glasses "oppose" each other when they are stirred together, creating artistic 3-D swirls. Baroque glass works well in almost all designs. It makes wonderful skies, water, flowers, just about anything you can think of. The clear baroque makes a beautiful background. You do have to work with the swirls when you cut the pieces, so that adjoining pieces of glass have the swirls connected at the right place. Otherwise, the panel look jumbled. Baroque is one of the types of glass that I love to use for backgrounds, especially where I need "movement".

Bevels are usually clear, thick plate glass with edges that have been ground and polished to an angle other than 90 degrees. Transmitted light is refracted and a prism-like effect results. They come in many sizes and shapes as well as clusters or sets. The clusters or sets make up a design entirely of bevels that can be incorporated in a stained glass panel. Single bevels make beautiful exterior and internal borders.

Cathedral Glass

Catspaw is a surface texture resulting from the chilling of hot glass on a cool table. The appearance is likened to the paw prints of a cat. Catspaw can be used as a feature in a panel. You wouldn't want to make the entire panel out of Catspaw, but it might work well for flowers, animals, grass...depending on the color mix you get.

Crackle glass is made like antique glass. The hot cylinder of glass is dipped in liquid, causing radical, random fissures in the glass. The cylinder is then reheated and further blown to heal the surface fissures. Resulting surface resembles the texture of alligator skin. Crackel Glass makes a nice background glass and it works well for borders. It is expensive compared to machine made stained glass.

Dichroic is a glass that has been coated with one or more ultra-thin crystalline layers of transparent metal oxides. The oxides enhance reflections at specific wavelengths of light resulting in striking effects with a brilliant change of color as you move your head while you're looking at it. It's very expensive and is usually sold by the square inch instead of the standard square foot. Dichroic Glass is mainly used in jewelry making and fusing (in a kiln), but it also works well in contemporary patterns with just a little bit used throughout the panel to catch the viewers eye.

Glass sheets with multiple dramatic folds, looking similar to folds in hanging drapes. Drapery Glass is a specialty glass, not used very often by the hobbyist, but I just wanted you to know about it. It's difficult to cut due to the huge variation in thickness. I've seen it used in contemporary designs giving a wonderful effect, and, of course, it can be used for flowing robes as seen in many church windows.

English Muffle is one of the types of glass produced by the Wissmach Glass Company. Originally popular in Victorian windows, English Muffle glass is being reintroduced in both restoration and contemporary stained glass work. English Muffle glass is known for its traditional muted colors, its highly refractive texture and crystalline quality. The texture appears as a non-directional ripple, allowing for minimal waste. English Muffle is one of my favorite glasses to work with. It's perfect for traditional and Victorian panels.

This is one of the many unique types of glass manufactured by the Bullseye Glass Company. Thin glass chips or shards (fractures) and/or glass string (streamers) are arranged on the casting table before the glass is poured, and thus pressed into the glass sheet as it is formed. Fracture and Streamer glass makes a beautiful background for a floral theme panel, or if the panel is a scene, it works well to emulate flowers in the distance. It's also nice for a beautiful box.

Gluechip is texture created on the surface of cold glass by applying hot animal glue and allowing it to dry under controlled temperature and humidity conditions. As the glue dries and contracts, it chips the glass surface in a natural and attractive pattern, likened to frost on a window pane. Glue chip glass makes nice borders, and the lighter colors make good background glass.

Iridescent is a surface treatment in which a layer of metallic oxide is bonded to the hot glass surface just after sheet-forming, resulting in a colorful, shimmering effect. Many different glasses are available with an iridescent surface. Clear, textured iridescent glass is perfect for angel wings. Many iridized glasses work well for borders and accent pieces in a panel, and also make beautiful boxes and kaleidoscopes.

A piece of glass that has been cut and faceted or press-molded into a geometric shape like a jewel. Jewels are often incorporated into stained glass projects.

Nuggets are also called glass gems or globs. They are a small, irregularly shaped "glob" of glass, flat on the bottom, rounded across the top. Nuggets are made by literally dropping a small amount of molten glass onto a flat surface. Like the jewels above, they are often incorporated into stained glass projects.

Any glass which is opaque (you can't see through it). There are degrees of opacity, with some types of glass being a mix of cathedral and opaque, giving you a semi opaque. For instance, you could have an opaque white and a cathedral blue swirled together giving you a semi opaque streaky glass. Opalescent glass comes in one solid color or multi colored with a two, three and four color mix. If it is multi colored, no two pieces of glass will ever look exactly alike due to the way the colors are mixed after they come out of the furnace. Opalescent Glass glass can be used any way you can imagine. It's extremely versatile...trees, flowers, leaves, grass, sky, borders, lampshades, boxes, you name it.

Ring Mottle Glass is an opalescent glass in which rates of crystal growth have been controlled to create ring-shaped areas of opacity. The effect is a visual surface mottling. Ring Mottle is a glass that won't be used often, but you will occasionally see a place for it. It does makes nice flowers and leaves, and is beautiful in lampshades.

Textured Glass is made by rolling and embossed roller over the hot glass after it's been poured on the table. One of the forming rolls is embossed with a texture that is imprinted on the glass as the sheet is formed. This produces glass smooth on one side and textured on the other. Some of these types of glass are "hammered," "granite," and "muffle." Textured glasses make great backgrounds, borders, geometric shapes such as diamonds. One of my designs has 5 trees in it, and I used textured glass, in large pieces, to give the appearance of leaves on the trees.

Waterglass is made by Spectrum Glass exclusively. The surface texture is created by stretching the hot glass sheet while it is still in a malleable state. The result is gentle, rolling waves that resemble the surface of a lake, stream, sky or grass. The pale colors make beautiful background glass.

Manufacturers of Glass Showing The Kinds of Glass They Make

The following links will take you to various glass manufacturer's web sites. Each one will open to their glass sample page so you can see the types of glass they make. You'll also find links to virtual tours of some of their factories giving you the opportunity to see how glass is actually made.

Lambert Antique Glass This site is from Germany and is written in German. Click on "Produkte", then "Mundgeblasene Flachglaser", then click on each one of the drop down boxes, to the right, to see the types of glass they make. If you have the time and feel inclined to watch, here's a 9 minute video from Lamberts that goes into detail about making antique glass. Making Antique Glass

Kokomo Opalescent Glass and Take a Tour of the Factory

Spectrum Glass Company and here you can take a Virtual Tour of how they make their glass.

Youghiogheny Glass and a Tour of their glass making facility.

I hope you have enjoy learning about the different types of glass used in stained glass work. This isn't a complete list, but it covers the majority of glass used most frequently. As you will notice when you look at the manufacturer's web site, each company has some of their own unique glass types that aren't made by any other company. You'll also see textures that I didn't mention above. There are so many different textures, it would take an entire page to list them all.

Use the manufacturer's web sites to choose colors when you're ready to work on a project. Then when you want to buy the glass, you'll have a good idea of the colors you want. You might not find the exact brand and color code, but you will be able to find something similar. Every stained glass shop does not carry all of the brands and their respective colors. That would be an enormous inventory for any business.

Whenever possible, shop for your glass locally. It's much easier to pick it out by looking at the exact piece rather than ordering online where you might get a piece with a color mix you don't like, or the streaks going in many directions when you wanted them going one way only.

Lastly, when you buy glass, be sure to ask for the manufacturer's name and the color code for the glass. Write it down and keep it in a safe place. You never know when you might want another piece, and just describing the glass to the lady in the stained glass shop might draw a blank stare!

Return from Types of Glass to Free Patterns For Stained Glass

This page was last updated on March 05, 2016

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Types of Glass used in Stained Glass Work

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There are hundreds, probably thousands, of types of glass, with their different colors and textures, used in stained glass work. They all start out being one of the 2 basic types, cathedral or opalescent, then expand from there. Cathedral glass is clear glass that you can see through.

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Some plastics learn to repair themselves | Science News for Students

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Some plastics learn to repair themselves | Science News for Students

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Some plastics learn to repair themselves

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A new material can fix its own scratches and small cracks. One day, it also may make self-healing paints and plastics possible.

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Materials - Materials Library - Institute of Making

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Materials - Materials Library - Institute of Making

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The Materials Library is a collection of some of the most wondrous materials on earth, gathered from sheds, labs, grottoes and repositories around the world. It is a resource, laboratory, studio, and playground for the curious and material-minded to conduct hands-on research through truly interdisciplinary inquiry and innovation. The collection is accessible to Institute of Making members day to day, and to the public at Materials Library Discovery sessions. Sign up to our mailing list to find out when the next session will be held.

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The Institute of Making is a cross-disciplinary research club for those interested in the made world: from makers of molecules to makers of buildings, synthetic skin to spacecraft, soup to diamonds, socks to cities.

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Other Compositions - Sparklers | PyroData

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Other Compositions - Sparklers | PyroData

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Other Compositions - Sparklers | PyroData

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Environmental Impacts of Mining | CK-12 Foundation

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Environmental Impacts of Mining | CK-12 Foundation

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RotoMetals-Hard to find Metals and Custom Alloys and other Cool Stuff

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RotoMetals-Hard to find Metals and Custom Alloys and other Cool Stuff

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RotoMetals-Hard to find Metals and Custom Alloys and other Cool Stuff

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Crab Shrimp Lobster Pot Anodes and Fishing Weights

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In these two practical activities, students use party poppers and sparklers to investigate the principles behind fireworks and explore, through flame tests, what creates different colours when fireworks are set off. They work in groups to make and share their observations. The activities offer the alternative of a group experiment or demonstration for the flame test activity.

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Free Guides Archive - Ceramic Arts Network

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Free Guides Archive - Ceramic Arts Network

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Free Guides Archive - Ceramic Arts Network

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Free downloadable recipes, techniques, and studio references! Download any of the freebies below and you will also receive a free subscription to the Ceramic Arts Daily Email Newsletter!

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Energy Lab Video Downloads - Switch Energy Project

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Energy Lab Video Downloads - Switch Energy Project

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Switch Energy Project - a film and educational video series dedicated to a smarter energy future

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Energy education programs and curricula for university and primary schools as well as general energy education resources.