UNIVERSITY of DELAWARE
DEPARTMENT of CHEMISTRY and BIOCHEMISTRY

 

Current Articles / Videos of Interest

 
I hope the information below is helpful or interesting to you. Feel free to email any comments for future additions.

 

     
Videos - click on titles below to view

 

Examples of Scientific Apparatus

Science by Fire

Gerhard Finkenbeiner Meets Alan Alda - Glass (quartz) Harmonica

Glassblowing Lathe in Motion

Basic Explanation of Annealing Glass (note one error in video- glass is an amorphous solid...NOT a super cooled liquid, as was believed for many years)

Articles


Lightweight, Metal-Like Glass Examined

Claudine Ryan, ABC Science Online

June 23, 2008 -- Airplane wings, golf clubs and engine parts made of glass alloys could be a step closer following new research into the chaotic structure of glass.
Researchers from the Bristol University, the Australian National University and the University of Tokyo, have identified what happens to the atoms within glass as it cools.

Their findings appear in the latest edition of Nature Materials and provide a new understanding of meta-stable materials. For decades, scientists have known that when glass cools from a molten state the atoms become jammed in a random pattern, whereas the atoms in metals form a regular, crystal lattice structure. Little has been known about why glass forms this way, because it's impossible to view the atoms in glass as they cool. The researchers used special particles called colloids that mimic atoms and can be seen through state-of-the-art microscopy.

When the colloids were cooled they formed a gel that sets out to become a crystal, but get trapped in a meta-stable state -- somewhere between a liquid and a crystal. As the researchers had suspected, the atoms become "jammed" due to the formation of icosahedra-like structures. "Some materials crystallize as they cool, arranging their atoms into a highly regular pattern called a lattice," Paddy Royall from the University of Bristol said. "But although glass 'wants' to be a crystal, as it cools the atoms become jammed in a nearly random arrangement, preventing it from forming a regular lattice."

The jammed random arrangement of atoms in glass is what makes it very strong, but brittle. Metals form a regular crystal lattice pattern, which allows them to be distorted or bent, but makes them less strong and prone to metal failure. Combining the two materials to form a metallic glass alloy, could result in a material that has strength and flexibility. Rob O'Donnell, a senior materials scientist from the CSIRO, says this research has identified the step that materials go through on the journey from being in a liquid glassy state to being crystalline, and could pave the way for newer alloys. " At the moment quasi-crystals are more of an anomaly. People see the quasi-crystals but don't actually make an entire quasi-crystalline material," O'Donnell said. "But if you knew how to do that, then it may enable you to make them more easily."

He says metallic glasses would be suitable for products that need to be very strong, very light and have a degree of flexibility that will allow them to bend a little and not break."Glassy metals probably will have much higher strength than a normal crystalline metal, improved corrosion resistance and they can produce lighter and stiffer components," O'Donnell said. "This research has helped identify the mechanism which will allow these metals to be able to make more easily."

 

The Nature of Glass Remains Anything but Clear

By KENNETH CHANG
Published: July 29, 2008

It is well known that panes of stained glass in old European churches are thicker at the bottom because glass is a slow-moving liquid that flows downward over centuries.

Well known, but wrong. Medieval stained glass makers were simply unable to make perfectly flat panes, and the windows were just as unevenly thick when new.

The tale contains a grain of truth about glass resembling a liquid, however. The arrangement of atoms and molecules in glass is indistinguishable from that of a liquid. But how can a liquid be as strikingly hard as glass?

“ They’re the thickest and gooiest of liquids and the most disordered and structureless of rigid solids,” said Peter Harrowell, a professor of chemistry at the University of Sydney in Australia, speaking of glasses, which can be formed from different raw materials. “They sit right at this really profound sort of puzzle.”

Philip W. Anderson, a Nobel Prize-winning physicist at Princeton, wrote in 1995: “The deepest and most interesting unsolved problem in solid state theory is probably the theory of the nature of glass and the glass transition.”

He added, “This could be the next breakthrough in the coming decade.”

Thirteen years later, scientists still disagree, with some vehemence, about the nature of glass.

Peter G. Wolynes, a professor of chemistry at the University of California, San Diego, thinks he essentially solved the glass problem two decades ago based on ideas of what glass would look like if cooled infinitely slowly. “I think we have a very good constructive theory of that these days,” Dr. Wolynes said. “Many people tell me this is very contentious. I disagree violently with them.”

Others, like Juan P. Garrahan, professor of physics at the University of Nottingham in England, and David Chandler, professor of chemistry at the University of California, Berkeley, have taken a different approach and are as certain that they are on the right track.

“ It surprises most people that we still don’t understand this,” said David R. Reichman, a professor of chemistry at Columbia, who takes yet another approach to the glass problem. “We don’t understand why glass should be a solid and how it forms.”

Dr. Reichman said of Dr. Wolynes’s theory, “I think a lot of the elements in it are correct,” but he said it was not a complete picture. Theorists are drawn to the problem, Dr. Reichman said, “because we think it’s not solved yet — except for Peter maybe.”

Scientists are slowly accumulating more clues. A few years ago, experiments and computer simulations revealed something unexpected: as molten glass cools, the molecules do not slow down uniformly. Some areas jam rigid first while in other regions the molecules continue to skitter around in a liquid-like fashion. More strangely, the fast-moving regions look no different from the slow-moving ones.

Meanwhile, computer simulations have become sophisticated and large enough to provide additional insights, and yet more theories have been proffered to explain glasses.

David A. Weitz, a physics professor at Harvard, joked, “There are more theories of the glass transition than there are theorists who propose them.” Dr. Weitz performs experiments using tiny particles suspended in liquids to mimic the behavior of glass, and he ducks out of the theoretical battles. “It just can get so controversial and so many loud arguments, and I don’t want to get involved with that myself.”

For scientists, glass is not just the glass of windows and jars, made of silica, sodium carbonate and calcium oxide. Rather, a glass is any solid in which the molecules are jumbled randomly. Many plastics like polycarbonate are glasses, as are many ceramics.

Understanding glass would not just solve a longstanding fundamental (and arguably Nobel-worthy) problem and perhaps lead to better glasses. That knowledge might benefit drug makers, for instance. Certain drugs, if they could be made in a stable glass structure instead of a crystalline form, would dissolve more quickly, allowing them to be taken orally instead of being injected. The tools and techniques applied to glass might also provide headway on other problems, in material science, biology and other fields, that look at general properties that arise out of many disordered interactions.

“ A glass is an example, probably the simplest example, of the truly complex,” Dr. Harrowell, the University of Sydney professor, said. In liquids, molecules jiggle around along random, jumbled paths. When cooled, a liquid either freezes, as water does into ice, or it does not freeze and forms a glass instead.
In freezing to a conventional solid, a liquid undergoes a so-called phase transition; the molecules line up next to and on top of one another in a simple, neat crystal pattern. When a liquid solidifies into a glass, this organized stacking is nowhere to be found. Instead, the molecules just move slower and slower and slower, until they are effectively not moving at all, trapped in a strange state between liquid and solid.

The glass transition differs from a usual phase transition in several other key ways. It takes energy, what is called latent heat, to line up the water molecules into ice. There is no latent heat in the formation of glass. The glass transition does not occur at a single, well-defined temperature; the slower the cooling, the lower the transition temperature. Even the definition of glass is arbitrary — basically a rate of flow so slow that it is too boring and time-consuming to watch. The final structure of the glass also depends on how slowly it has been cooled. By contrast, water, cooled quickly or cooled slowly, consistently crystallizes to the same ice structure at 32 degrees Fahrenheit.

To develop his theory, Dr. Wolynes zeroed in on an observation made decades ago, that the viscosity of a glass was related to the amount of entropy, a measure of disorder, in the glass. Further, if a glass could be formed by cooling at an infinitely slow rate, the entropy would vanish at a temperature well above absolute zero, violating the third law of thermodynamics, which states that entropy vanishes at absolute zero.
Dr. Wolynes and his collaborators came up with a mathematical model to describe this hypothetical, impossible glass, calling it an “ideal glass.” Based on this ideal glass, they said the properties of real glasses could be deduced, although exact calculations were too hard to perform. That was in the 1980s. “I thought in 1990 the problem was solved,” Dr. Wolynes said, and he moved on to other work.

Not everyone found the theory satisfying. Dr. Wolynes and his collaborators so insisted they were right that “you had the impression they were trying to sell you an old car,” said Jean-Philippe Bouchaud of the Atomic Energy Commission in France. “I think Peter is not the best advocate of his own ideas. He tends to oversell his own theory.”Around that time, the first hints of the dichotomy of fast-moving and slow-moving regions in a solidifying glass were seen in experiments, and computer simulations predicted that this pattern, called dynamical heterogeneity, should exist.

Dr. Weitz of Harvard had been working for a couple of decades with colloids, or suspensions of plastic spheres in liquids, and he thought he could use them to study the glass transition. As the liquid is squeezed out, the colloid particles undergo the same change as a cooling glass. With the colloids, Dr. Weitz could photograph the movements of each particle in a colloidal glass and show that some chunks of particles moved quickly while most hardly moved. “You can see them,” Dr. Weitz said. “You can see them so clearly.”

The new findings did not faze Dr. Wolynes. Around 2000, he returned to the glass problem, convinced that with techniques he had used in solving protein folding problems, he could fill in some of the computational gaps in his glass theory. Among the calculations, he found that dynamical heterogeneity was a natural consequence of the theory.

Dr. Bouchaud and a colleague, Giulio Biroli, revisited Dr. Wolynes’s theory, translating it into terms they could more easily understand and coming up with predictions that could be compared with experiments. “For a long time, I didn’t really believe in the whole story, but with time I became more and more convinced there is something very deep in the theory,” Dr. Bouchaud said. “I think these people had fantastic intuition about how the whole problem should be attacked.”

For Dr. Garrahan, the University of Nottingham scientist, and Dr. Chandler, the Berkeley scientist, the contrast between fast- and slow-moving regions was so striking compared with the other changes near the transition, they focused on these dynamics. They said that the fundamental process in the glass transition was a phase transition in the trajectories, from flowing to jammed, rather than a change in structure seen in most phase transitions. “You don’t see anything interesting in the structure of these glass formers, unless you look at space and time,” Dr. Garrahan said.

They ignore the more subtle effects related to the impossible-to-reach ideal glass state. “If I can never get there, these are metaphysical temperatures,” Dr. Chandler said.
Dr. Chandler and Dr. Garrahan have devised and solved mathematical models, but, like Dr. Wolynes, they have not yet convinced everyone of how the model is related to real glasses. The theory does not try to explain the presumed connection between entropy and viscosity, and some scientists said they found it hard to believe that the connection was just coincidence and unrelated to the glass transition.

Dr. Harrowell said that in the proposed theories so far, the theorists have had to guess about elementary atomic properties of glass not yet observed, and he wondered whether one theory could cover all glasses, since glasses are defined not by a common characteristic they possess, but rather a common characteristic they lack: order. And there could be many reasons that order is thwarted. “If I showed you a room without an elephant in the room, the question ‘why is there not an elephant in the room?’ is not a well-posed question,” Dr. Harrowell said.

New experiments and computer simulations may offer better explanations about glass. Simulations by Dr. Harrowell and his co-workers have been able to predict, based on the pattern of vibration frequencies, which areas were likely to be jammed and which were likely to continue moving. The softer places, which vibrate at lower frequencies, moved more freely.

Mark D. Ediger, a professor of chemistry at the University of Wisconsin, Madison, has found a way to make thin films of glass with the more stable structure of a glass that has been “aged” for at least 10,000 years. He hopes the films will help test Dr. Wolynes’s theory and point to what really happens as glass approaches its ideal state, since no one expects the third law of thermodynamics to fall away.

Dr. Weitz of Harvard continues to squeeze colloids, except now the particles are made of compressible gels, enabling the colloidal glasses to exhibit a wider range of glassy behavior.

“When we can say what structure is present in glasses, that will be a real bit of progress,” Dr. Harrowell said. “And hopefully something that will have broader implications than just the glass field."

 


BEYOND THE IVORY TOWER:
A World of Glass
Alan Macfarlane and Gerry Martin*

Anyone who has looked at the long-term history of human civilizations over the last 50,000 years will notice that one of the most significant transformations took place during the period 1200 to 1850. This transformation affected two of the most important human capacities: the way in which we think and our sense of sight. Compare the nature of painting in Europe in 1200 with that in 1850, or the amount of chemical, physical, and biological knowledge in Europe in 1200 to that in 1850, and one would not hesitate to pronounce that a revolution took place within this 650-year period. This revolution manifested itself not only in the world of art and architecture, but also in transport, housing, energy sources, agriculture, and manufacturing.

We know that all this happened, but after that there is little agreement. We are still uncertain as to why the Renaissance of the 14th, 15th, and 16th centuries, and the scientific and industrial revolutions of the 17th and 18th centuries took place. Nor do we understand why these sweeping changes happened in western Europe, and not in the great Islamic or Chinese civilizations.

The interplay between the availability of more reliable information and the improved manufacture of tools, instruments, and artifacts contributed to the remarkable changes that swept through western Europe. Often in history, we witness the generation of new knowledge through experimentation, which then leads to significant innovations and a richer appreciation of new or improved physical artifacts. These artifacts, if they are useful, in demand, and relatively easy to produce, are often disseminated in large quantities. These objects then change the conditions of everyday life and may fund further theoretical explorations. Such artifacts can do this in two ways: by generating wealth that funds increased efforts to acquire fresh knowledge and by providing better tools for scientific enquiry.

Historically, this triangle of knowledge-innovation-quantification emerged in many spheres of life, most notably in agriculture. The loop is enduring when artifacts are widely disseminated and is a cumulative process. The speed of movement around the triangle and the frequency of its repetition provide a measure of the development of human civilizations. Our analysis of this triangle in the history of glass production and application reveals that glass contributed to the rampant changes that swept through western Europe between 1200 and 1850.*

A Brief History of Glass
No one is certain where, when, or how glass originated. It may have appeared first in the Middle East in regions such as Egypt and Mesopotamia around 3000 to 2000 B.C. although there are hints of glazing on pottery as early as 8000 B.C. Glass was almost certainly discovered by accident--so the Roman historian Pliny (A.D. 23-79) tells us--by Phoenician traders, who apparently noticed that a clear liquid formed when the nitrate blocks on which they placed their cooking pots melted and mixed with sand from the beach. Egyptian craftsmen developed a method for producing glass vessels around 1500 B.C., and the first manual of glassmaking appeared on Assyrian stone tablets about 650 B.C. About 2000 years ago, Syrian craftsmen invented glassblowing, a skill adopted by the Romans, who carried it with them as they swept through western Europe on their conquests. The rise of Venice to prominence in the 13th century enabled this city to become the center of glassmaking in the western world. As the industrial revolution gathered momentum, new manufacturing technologies enabled the mass production of glass scientific instruments, bottles, window panes, and many other items.

The Many Uses of Glass
Historically, glass has been used in five different ways, which varied depending on the locality. Glass beads, counters, toys, and jewelry were produced almost universally throughout Eurasia before 1850, with glass becoming a substitute for precious stones. The great developers of glass vessels, vases, and containers were the Italians, first the Romans and later the Venetians. The use of glass vessels was largely restricted to the western part of Eurasia until the 1850s, with little evidence of use in India, China, and Japan. In the Islamic territories and Russia, the use of glass declined dramatically from about the 14th century until modern times due to the Mongol incursions.

Another crucial use of glass was for making windows. Until the 20th century, window glass was found mainly in the western regions of Eurasia (principally north of the Alps), appearing rarely in China, Japan, and India. Another application of glass depended on its reflective capacity when silvered. Produced by the Venetians in the 16th century, the use of glass mirrors spread throughout the whole of western Europe, but appeared rarely if at all in Islamic civilizations or in India, China, or Japan. A final critical application of glass was in the production of lenses and prisms. This led to the manufacture of spectacles to improve human sight; eyeglasses first appeared in Europe during the 13th and 14th centuries. The concept of the light-bending and magnifying properties of glass, discovered by the Chinese in the 12th century, was probably known to all Eurasian civilizations. Yet only in western Europe did the practice of making lenses really develop. This coincides precisely with the surge in interest in optics and mathematics during medieval times, which fed into other branches of learning, including architecture and painting.

The reasons for the different uses of glass in different parts of the world may be largely accidental, reflecting variations in climate, drinking habits, availability of pottery, political events, and many othercharacteristics. Intention, planning, individual psychology, superior intellect, or better resources seem to have little to do with it. Yet these accidents instigated the move of western European societies around the knowledge-innovation-quantification triangle. Improvements in glassmaking and the production of more sophisticated glass instruments yielded more accurate information about the natural and physical worlds, which fed back into refinements in glass manufacture and, hence, in glass quality.

Glass and Scientific Knowledge
Glass helped to accelerate the amazing acquisition of knowledge about the natural and physical worlds by providing new scientific instruments: microscopes, telescopes, barometers, thermometers, vacuum flasks, retort flasks, and many others. Glass literally opened people's eyes and minds to new possibilities and turned western civilization from an aural to a visual mode of interpreting experience. We randomly picked 20 famous experiments that changed our world--Thomson's discovery of electrons, Faraday's work on electricity, and Newton's splitting of white light into its component colors with a prism, for example--and found that 15 of them could not have been performed without glass tools. That the knowledge revolution of the last 500 years took place in western Europe and not elsewhere, can be attributed in part to the collapse of glass manufacturing in Islamic civilizations and its diminished importance in India, Japan, and China.

The list of scientific fields of enquiry that could not have existed without glass instrumentation are legion: histology, pathology, protozoology, bacteriology, and molecular biology to name but a few. Astronomy, the more general biological sciences, physics, mineralogy, engineering, paleontology, vulcanology, and geology would have emerged much more slowly and in a very different form without the help of glass instruments. For example, without clear glass, the gas laws would not have been discovered and so there would have been no steam engine, no internal combustion engine, no electricity, no light bulbs, no cameras, and no television. Without clear glass, Hooke, van Leeuwenhoek, Pasteur, and Koch would not have been able to visualize microorganisms under the microscope, an achievement that led to the birth of germ theory and a new understanding of infectious disease, which launched the medical revolution (see the photograph on page 1407).

Chemistry depends heavily on glass instrumentation. Thanks to glass, European scientists elucidated the chemistry of nitrogen and learned to fix this gas in the form of ammonia to produce artificial nitrogenous fertilizers, a huge step forward in 19th- and 20th-century agriculture. Without glass, there would have been no means of demonstrating the structure of the solar system, no measurement of stellar parallax, no way of substantiating the conjectures of Copernicus and Galileo. The application of glass instruments revolutionized our understanding of the universe and deep space, completely altering our whole concept of cosmology. Furthermore, without glass, we would have no understanding of cell division (or of cells), no detailed understanding of genetics, and certainly no discovery of DNA. Without spectacles, most individuals over the age of 50 would not have been able to read this article. Glass may be an unforeseen accident, but it follows a predictable pattern of movement around the triangle: deeper reliable knowledge enabling the manufacture of innovative artifacts followed by their mass production.

Glass in Everyday Life
We have discussed the contributions of glass from the scientific perspective. But from 1200 onwards, all knowledge was interconnected. Without mirrors, lenses, and panes of glass, the startling changes that marked the Renaissance would not have taken place. A new understanding of the laws of optics, and the accuracy and precision of paintings by Da Vinci, Durer, and their contemporaries largely depended on glass instruments of various kinds. The divergence of world art systems between 1350 and 1500 is impossible to imagine without the development of very high quality glass by the Venetians. Glass in the form of church stained-glass windows affected what we believed; in the form of mirrors, it affected how we perceived ourselves.

Glass, however, is not just a tool to think and perceive with, but also a tool to improve everyday life. The period between the 13th and mid-19th centuries in Europe saw many changes made possible by glass that contributed not only to the intellectual flowering of this era but also to an improved standard of living for many people. For example, glass in the form of windows lengthened the working day and improved conditions for workers. Glass let light into interiors allowing house dirt to become more apparent leading to improvements in hygiene and health. Also, glass is a tough, protective surface that is easy to clean. Glass windows wrought changes not only in private homes, but also in shops with shopkeepers eventually placing much of their produce and merchandise behind glass windows and under glass cabinets.

This clear molten liquid began to transform agriculture and horticulture. The use of glass houses to promote the precocious growth of plants was not an invention of early modern Europe. Indeed, the Romans used forcing houses to promote plant growth and protected their grapes with glass. The Roman idea was revived in the later Middle Ages, when glass pavilions for growing flowers and later fruit and vegetables began to appear. As glass became cheaper and, particularly, flat window glass improved in quality, many more applications appeared. Glass cloches and greenhouses improved the cultivation of fruit and vegetables, bringing a healthier diet to the population. In the 19th century, glass made it possible to bring plants from all over the world to enrich European farms and gardens.

There are many other useful applications of glass that altered everyday life from the 15th century onward. Among them were storm-proof lanterns, enclosed coaches, watch-glasses, lighthouses, and street lighting. The sextant required glass, and the precision chronometer invented by Harrison in 1714, which provided a solution to calculating longitude at sea, would not have been possible without glass. Thus, glass directly contributed to navigation and travel. Then, there was the contribution of glass bottles, which increasingly revolutionized the distribution and storage of drinks, foods, and medicines. Indeed, glass bottles created a revolution in drinking habits by allowing wine and beer to be more easily stored and transported. First through drinking vessels and windows, then through lanterns, lighthouses, and greenhouses, and finally through cameras, television, and many other glass artifacts, our modern world has emerged from a sea of glass.

The different applications of glass are all interconnected--windows improved working conditions, spectacles lengthened working life, stained glass added to the fascination and mystery of light and, hence, a desire to study optics. The rich set of interconnections of this largely invisible substance have made glass both fascinating and powerful, a molten liquid that has shaped our world.

 

 

Enhance the Service: Eliminate the Competition

FUSION, Journal of The American Scientific Glassblowers Society, May 2007

Are you concerned that the glassblowing services you provide could potentially be outsourced? If so, you are not alone. Through discussions with ASGS friends, I have learned that many glassblowers share this apprehension to some extent. While this article focuses mainly on outsourcing concerns facing university and other research glassblowers—the most targeted groups to date—hopefully the information will be helpful to others also. Its purpose is not to create additional anxiety, but rather to promote confidence and strengthen job security.

Within the past couple of years, we have all heard horror stories of a few institutions outsourcing glassblowing services. Fast spreading reports of each incident have ruffled some feathers in the glassblowing community. You may wonder why institutions would elect to make those decisions. You may even ask yourself if those decisions were fair. Surprisingly, I have heard conflicting opinions, not only from case to case, but also from person to person.

Undoubtedly, one reason for institutions to consider outsourcing is a decline in government funding, a situation which has certainly made writing grant proposals more competitive. That situation will probably not change in the near future. Also, floor space is extremely expensive and under constant evaluation for highest priority usage. (This could be the main reason many of us are located in basements or somewhat less sought after areas.) Furthermore, some glassware manufacturers have been forced to consider creative ways to compete with less expensive foreign-made products. As a result, some of these companies have decided that they must offer outsourcing services to survive, even though this is an extremely unpopular practice. They try to appeal to employers by offering to pick up and drop off glassware a couple times a week. Their plan is to work toward being the sole source for all glass needs. Unfortunately, these factors are out of our control.

Outsourcing glassblowing services usually comes into play as an attempt to cut expenses or expand another initiative believed to be a more worthwhile endeavor at that time. However there is another consideration—a very important consideration that employers should evaluate: Are outsiders able to provide services that benefit research efforts, like we can? The answer to that question depends a lot on us and the actions we choose to take. I am thoroughly convinced that we can provide better overall research enhancing services “in-house.” After all, researchers like having us readily available for assisting with design, making changes along the way, or providing immediate support when a problem arises. They greatly appreciate and value our assistance; we definitely provide a nice convenience for them. However, like it or not …we are not a “necessity.”

As I see it, we have only two possible choices. We can offer basic fabrication and repair services, as has been done through the years, and hope to retain our job until retirement. Of course we would be taking a risk that our employers could very well contemplate better uses for our area after we are gone. Or, we can choose to do as some have and include other beneficial services that outside concerns cannot provide. Without question, most of us care about our profession and would choose the more active role, not only to secure our positions but also to enhance research efforts. For those individuals, I offer the following suggestions.

Although it can be difficult at times, the key is to be customer service oriented as much as possible, and also be willing to accept inevitable change. Along with assuring each visitor you can confidently design and fabricate glassware or instruments, be more aggressive in recommending other viable ideas or solutions. Never act as though a job is a lot of trouble or make researchers think they have inconvenienced you unnecessarily. This behavior would create an uncomfortable atmosphere, forcing them to seek assistance elsewhere. They should always feel welcome in your shop, even if they managed to break the same item two or three times. (By the way, if you find this to be a continuous problem you may consider redesigning the glassware so it will be structurally stronger for their particular application.) Also seek to understand what the researchers are trying to achieve and consider how you can help them get results easier, faster or more economically. Go see how the research groups are using your glassware. Make some evaluations: Is it mounted and clamped correctly? Are stopcocks greased and operating properly? Do you notice any vacuum, contamination or other potential problems?

You will discover that most researchers do appreciate a tip that may improve their research efforts or possibly lessen breakage. Now I am not suggesting that you “drive a point home” or make them feel as though you are overstepping your bounds. This behavior would surely lead to poor relations. You want them to feel you are a team player and a useful resource they can depend on. Also, never say, “I don’t know” without following up with “I’ll try to find out and get back to you.” Occasionally a job may come in requiring specialized machining, plating or other service beyond the capability of your shop. In this case, offer to find a reliable resource that can do their job at a reasonable price. Researchers should feel confident knowing that they will leave our shops with a solution, or at the very least, less of a problem than when they came.

In addition, try to maintain an up-to-date technical and material library to assist in locating almost anything that may be needed. Volunteer to go online and track down hard-to-find glass or related equipment. Many Web sources provide new, used or even discontinued items. If time allows, go the extra mile to find out availability or prices. It may take a little extra time, but your effort will be appreciated. In other words, don’t limit yourself to only fabricating and repairing glassware. You may want to offer the service of salvaging glass apparatus and instruments that can be utilized by another department or group. It involves requesting unused items be brought to you, or possibly visiting recently vacated labs to gather them up before they are indiscriminately discarded. These items can then be cleaned, repaired and offered to the research community. Another popular service you may consider is disposal of obsolete glassware or related instruments. Some of these items require strict reclamation or recycling procedures, and may stipulate you work closely with Occupational Health and Safety.

If you haven’t done so already, you might try creating a Web site to show the full capabilities of your glass shop. Depending on information posted, it could prove to be a valuable resource for your research groups. Lastly, you may consider volunteering for or accepting temporary committee positions when asked. Although some may be quite time consuming (and cause a larger backlog), I have actually found they provide rewarding experiences overall. Always take advantage of the opportunity to provide input that may affect the direction and future of your unit.

Most of you are already important assets to your institutions and currently offer many varied services. It is to our benefit--and definitely to the benefit of our colleagues--that we avoid complaisance and maintain a dedicated work ethic and enthusiastic attitude. We should be an easily approachable and useful resource that researchers consider crucial to their team. We can blame others for what seems to be a growing outsourcing trend in our field, or we can concentrate on what we CAN do: We can change our viewpoint, expand our services, and facilitate research in the process. Remember that institutions with strong R&D programs almost always employ at least one in-house glassblower. Therefore, it is certainly in our best interest to help them grow. Of course we do not have the time or energy to solve every problem encountered in an eight hour day. Our services offered must be limited due to individual time constraints and workload. However, we should re-evaluate those restraints periodically to provide realistic services that prove to be most beneficial.

I am fortunate to have recently been relocated to a newly renovated shop. I’d like to believe that my efforts and services have helped justify the cost, inconveniences incurred and more importantly the area. My hope is to remain a valuable resource here at the University of Delaware. My goal is the same as many of yours, which is to maintain the need for future scientific glassblowers that will fill our shoes one day.

Submitted to A.S.G.S. by: Doug Nixon
University of Delaware
Dept of Chemistry and Biochemistry


 
Did you ever wonder where the odd or interesting names came from for much of our glassware or instruments?
This article explains some of them, as well as a few quirky and tragic facts about the individuals themselves....  

Famous Names in Glass Apparatus- By J. Lees
Department of Physics, University of B.C.
Vancouver, B.C., Canada

This paper is the result of a casual interest in the names of glass apparatus found in catalogues of scientific glassware. I found myself wondering why a beaker should be a Berzelius” beaker, or a gauge a McLeod” gauge. I wondered also how long these names had been in use. Eventually, I began to do a little digging in our library and was amazed at the way these names seemed to spread over the whole history of science. It was very gratifying to find that these famous men had so close an association with glass apparatus, but a little disconcerting to find no mention at all of the Glassblowers who had manufactured the apparatus.
It soon became clear that the early scientists were largely of the wealthy class, and that their interests often spread over many unrelated fields. The study of Natural Philosophy, as it was then called, was often a consuming hobby of the rich. However, as with all rules, there were notable exceptions to this one also. Faraday, for example, was the son of a blacksmith and started his working life as an apprentice to a bookbinder. It is also interesting to note that many scientists suffered physically in some way from their work. Bunsen lost an eye in a laboratory explosion, as did Dewar’s assistants, Lenox and Heath. Many suffered from arsenical or lead poisoning, while mercury was so commonly used that almost all contracted mercury poisoning in various degrees. In point of fact, it was not until a thorough investigation of the toxic effects of mercury was made in the nineteen twenties by a German chemist, Alfred Stock, that the hazardous nature of mercury use was realized. Even today, we find a great deal of laxity in its use.


In order to keep this dissertation within reasonable limits I have had to reduce along list to about twenty names. The final selection is my own while the basis for that selection, I must confess, is my own interest. I trust, therefore, that in this instance, my interests will coincide with yours. I have followed no particular chronological order, but have picked out names and incidents which I found usually instructive, often entertaining, and sometimes amusing. The amount of time devoted to each depends partly on the importance of the individual, but mostly on just how much information I was able to obtain about him. In each case, I have tried to give dates of birth and death, with some idea of his main contributions to Science.


Pride of place goes to Jons Jacob Berzelius (1779-1848), a Swedish chemist known to the world as the father of modern chemistry, but known to us as the designer of the Berzelius form of beaker. His activities illustrate perfectly the wide range of interests of the early scientists. He first qualified as a Doctor of Medicine, then became successively, Professor of Botany, then Pharmacy, and finally Chemistry in 1815. In chemistry, he has left an indelible mark. He produced the first reliable table of atomic weights, discovered the elements Selenium (1818), Silicon (1824), and Thorium (1829). He invented the words Isomer, Catalyst, and Protein. He also invented and popularized the system of chemical symbols still in use today, where the Symbol for an element is the first letter of its Latin name, plus, where it may be necessary, another letter from the rest of the name. Thus Nitrogen is represented by N, and calcium by Ca, and so on. He even invented the name Radical, to denote a stable molecule. It is a wry circumstance that what then meant stable now means almost exactly the opposite when applied to some of our modern students. By 1830, Berzelius was the world authority on chemistry, of such fame that even Goethe was proud to have had lunch with him. It is not well known that Goethe was also something of a scientist, interested in geology and zoology. He actually published a long text on the nature of light, but his theories were soon proved to be quite wrong. Berzelius became very conservative in his old age and was on the wrong side of almost all the scientific arguments of his later years. However, at the age of fifty-six he surprised everyone by marrying a beautiful young lady of twenty-four. As a wedding present, King Charles XIV of Sweden conferred on him the title of Baron. (I must confess that in the present concern about the population explosion and the Pill, I first misread this item as “As a wedding present, King Charles of Sweden made him Baron.”).

For about thirty years after the death of Berzelius, the dominant figure in Chemistry was Baron Justus Von Liebig (1803-1873). He stared life as an apothecary’s apprentice, but, through the help of some influential friends, managed to obtain a position in the laboratories of Gay-Lussac, in Paris. In 1824, when twenty-one years old, he became Professor of Chemistry at the University of Geissen. There he introduced a tremendous innovation by setting up the first laboratory ever for student use. This set a completely new pattern in the instruction of science students. In collaboration with Wohler, he was responsible for much of the early work in organic chemistry, and was also one of the first to experiment with chemical fertilizers. In appreciation for his work, he was made a Baron in 1842. To us, he is known as the inventor of the most famous and widely used of all condensers, the Liebig condenser.
August Wilhelm Von Hofman (1818-1892) was the natural successor to Liebig. He became famous for the synthesis of dyes and was so far ahead of the rest of the world in this field that his work gave Germany a virtual monopoly for many years. He was one of Liebig’s students, and also had the good sense to marry his professor’s niece. He deserves mention here as the inventor of one of our most useful little gadgets, the pinchcock. The correct name of this handy little device, according to Webster, is the Hofman clamp.


To continue with useful tools, we come to the burner popularized by Robert Wihelm Von Bunsen (1811-1899). An almost identical burner, working on the same principle, was invented and used by Faraday prior to Bunsen’s burner. However, Bunsen, besides being a very prominent chemist, was quite adept at public relations, so that it is his name which is universally associated with this type of burner. He did a considerable amount of work on gases produced in blast furnaces and invented a number of very ingenious calorimeters for measuring heat. This work led to an investigation of the Geysers of Iceland in the late 1840’s. Bunsen produced the first explanation of the workings of geysers which subject had, until that time, been shrouded in superstitious mystery. He was the prolific inventor, two of his inventions being a carbon-zinc battery, and a grease-spot photometer. He was the first to produce magnesium in quantity, thus opening the way for its use in photography. In 1880, together with Kirckhoff, he developed the technique of spectroscopy and so discovered two new elements, Cesium, and Rubidium. Bunsen never married and usually explained this by saying “But Good God man, I’ve never had time to get married!” This incidentally, was also the excuse of John Dalton, of atomic theory fame.


It is of some interest to note that the oxyhydrogen blowpipe was the invention of an American chemist, Robert Hare, who died in 1858. Hare’s first occupation was the managing of his father’s brewery, but he eventually became a Professor of Chemistyr, and was associated with Silliman, whom we know was the inventor of the refractory, Sillimanite. It is now hard to believe that most of the scientific community of that time refused to believe that meteors were simply rocks falling from the sky. Demonstrating the natural origins of meteors was Silliman’s major contribution to science.
Another odd theory which was held sway in that period was “Vitalism.” This theory claimed that chemical changes in the body were different from other chemical changes and were brought about only by a mysterious “Life Force” within the body. Buchner (1860-1917), a German chemist, won a Nobel prize for his work on fermentation which completely disproved the vitalist theories. He was, of course, the inventor of the Buchner funnel which is still widely used. Buchner was killed in action in Rumania during the first World War.


One piece of equipment which is still in use by every glass blower who ever built a vacuum system is the Tesla coil. Its inventor was an electrical engineer named Nikola Tesla. He was a naturalized American, born in Hungary in 1856, and was involved in one of the bitterest scientific disputes of his time. He came to America in 1884 where for a time he was associated with Edison. Edison went back on a promise to pay Tesla for one of Tesla’s inventions, which unfair treatment caused Tesla to go into business for himself. He developed transformers to enable power to be transported cheaply at high tension and designed generators and motors and transmission equipment, all of course using A.C. current. The use of electrical power was just beginning at that time, and a great dispute had arisen over whether A.C. or D.C. should be the system used. Edison was the proponent of D.C., while Telsa in association with George Westinghouse was strongly supporting the use of A.C. Edison’s prestige was enormous, but subsequent events have proved him quite wrong in this case. The argument was very bitter, and unscrupulous tactics were used. Edison even went so far as to privately advise the New York authorities to use A.C. for their newly introduced electric chair, then he publicly expressed pious horror at the deadly nature of A.C. in this use. At an enquiry into the relative merits of the two systems, Tesla, testifying under oath, was asked by an opponent to state who was the leading world authority on electricity. He replied “I am.” Later, when his friends were chiding him for such immodesty, he said “But what else could I say, I was under oath.” The deciding event came when the Westinghouse Company, manufacturing Tesla’s designs, was given the contract for the generating station and transmission lines at Niagara Falls. Later, the Nobel prize was to have been awarded jointly to Tesla and Edison, but Tesla was so incensed at Edison’s unscrupulous tactics that he refused absolutely to be associated with Edison in any way, so the prize went to neither man.


We come now to another name known to all glassblowers, the Dewar Flask. This was invented by James, afterwards, in 1904, Sir James Dewar (1842-1923). He was youngest of seven sons of a Scottish innkeeper. When ten years old, he fell through thin ice and, as a consequence, suffered ill health for some time afterwards. During the convalescent period, he learned to make fiddles. One of these, dated 1854. when he twelve years old, was played at his golden wedding celebration. Eventually, Dewar became Professor of Chemistry at the Royal Institution in London, where he gave a brilliant series of lecture demonstrations over a period of thirty years. During this time, there was intense competition in the world of science to be the first to liquefy Hydrogen. This Dewar achieved in 1898, but the subsequent race to liquefy Helium was won by Kammerlingh Onnes in Leiden in 1908. Dewar never got over this disappointment and gave up his work on low temperatures to follow an earlier interest in the study of the films of soap bubbles. During his career, he had, with Abel, invented Cordite. They took out a patent for this invention and were unsuccessfully sued by Nobel, who claimed that he had given the ideas to Dewar during long discussions on the subject. Before the Dewar flask, liquefied gases were contained in a double vessel with the space between the inner and outer portions containing either a drying agent such as calcium chloride or else liquid ethylene, the vapour of which was continually pumped away. Dewar’s vacuum flask made it possible to keep gases in a liquid state at very low temperatures for long periods. It could have been known as the Weinhold flask or the “Vase d’Arsonval” for both of these gentlemen claimed the idea as their own. However, there is no doubt whatever but that the credit should go solely to Dewar. His design has never been improved on, which fact is a high tribute to its effectiveness. Dewar was an irascible Scot who engaged in many feuds and seemed to enjoy doing so. In his later years, he quarreled with all his friends, but his wife stood by him till the end, and indeed, they were the perfect example of a devoted married couple. Dewar had a strangely sensitive and artistic side to his character. He was very fond of music and would often sponsor struggling young musicians. He would quietly buy up all unsold tickets for their concerts then distribute them for free so that there was certain to be an audience. I would like to leave him with a quote from “The Quest for Absolute Zero” by K. Mendelssohn: “Dewar’s rule in his laboratory was as absolute as that of a Pharaoh, and he showed deference to no one except the ghost of Faraday whom he met occasionally all night in the gallery behind the lecture room.”


Some of our more mature glass blowers present today may have at some time had to construct a “Nernst” lamp with a ceramic filament. This is my excuse for mentioning Walther Herman Nernst (1864-1941), a very prominent physical chemist who is best known for his work on specific heats at low temperatures. Two of the student assistants at his laboratory in Berlin were the brothers of F.A. and Charles Lindeman, two energetic Englishmen from a well-to-do family. F.A. Lindeman became Viscount Cherwell, the scientific advisor to Winston Churchill and official head of the back-room boys, or boffins, in World War Two. The Lindeman brothers were keen tennis players and insisted on a game every day. Nernst, who was something of a slave driver, could not understand this athletic fervor, and finally his irritation caused him to complain peevishly. “Hah! How grown men chasing one little ball! You are so rich, why don’t you buy one each?” Nernst sold the patent rights to his lamp for a considerable sum with which he bought a country estate. One winter, he noticed that although there was snow outside, his barn was very warm inside. He realized that the heat was coming from the natural metabolism of his cows and was in fact originating with the feed which he gave them. He decided that this was thermodynamically wasteful, so he sold all his cattle, had ponds dug on his land, and from then on he bred carp. His argument was that if he was going to put good money into producing meat, then it had to be done without such a wasteful increase in entropy.


Now we come to our pride and joy, the inventor of the Geissler tube, Heinrich Geissler (1814-1879), who is the only one of our subjects who was a glassblower in his own right. He owned and operated a scientific instrument shop where he manufactured instruments and experimented with his own designs. He invented a vacuum pump operating on a similar principle to the Topler pump. His pump was the first to produce a low enough pressure to permit the operation of the famous tubes known universally as Geissler tubes. These original discharge tubes led directly to the discovery of the electron by J. J. Thompson. Geissler was a very skilled glassblower who must have gained a tremendous amount of pleasure from producing the complicated designs of his tubes. It is intriguing to note that even today, the scientific instrument catalogues still offer the same fantastic shapes which Geissler first produced. Science is occasionally very conservative. Everyone passing through a High School physics laboratory must have seen the Maltese Cross tube, yet this ubiquitous cross could just as well have been an Isosceles Triangle or a fleur de lys.


I would like to mention now one name which is not well-known to glassblowers, that of Karl Auer (1858-1929), who is better known as Baron Von Wellsbach, the inventor of the Wellsbach incandescent mantle. He is of interest to us because of two other accomplishments. He did the pioneer work on the rare earth Didymium, which name should certainly sound familiar. Auer demonstrated that Didymium is actually a mixture of two other elements which he called Praesodymium, and Neodymium. His work on rarer earths led to his other accomplishment, the invention of Misch metal, which is a mixture of rare earths, mainly Cerium, with finely divided iron. If you have not heard of Mischmetal, you will perhaps wonder why it should be important to us. It is, for one thing, a very useful getter for oxygen removal, but mainly, every time you use a flint gas lighter to light your torch, that flint you are striking is Mischmetal.
I had intended at this point to discuss the name Corning. However, when I looked it up in Webster’s encyclopedia, I found that Corning is the present participle of the verb to corn. I felt that no improvement could be made on this statement.


I must now deal briefly with a few other well-known names. Franz Von Soxhlet, who died in 1926, was a German chemist who invented the ingenious method of extraction embodies in the Soxhlet extractor. Johan Kjeldahl, a Dane who died in 1910, was responsible for the design of the Kjeldghl flask used originally for nitrogen determinations. Another flask, designed by Emil Erlenmeyer has a special shape so that the contents can be shaken laterally without danger of spilling. A Dutchman, Petrus Jacobus Kipps, invented the Kipps Hydrogen Generator which is still a standard in many first year chemistry laboratories. However, Florence flasks are a disappointment. They were used as containers for wine and olive oil and were associated mainly with the city of Florence. The Petri dish, used in the preparation of bacterial cultures was the invention of Julius Richard Petri who was an assistant to Robert Koch, the discoverer of the bacilli of anthrax, Cholera, Tuberculosis, Bubonic Plague, and others. Koch originally prepared his cultures on plain flat slides and the story is that Petri designed his dish because he got so fed up with having to clean up the mess in the lab.


Condensers have a varied and cosmopolitan origin. There was Liebig, a German, Allihn, a Frenchman, Hopkins, a Englishman, and among others, Thomas D. Graham, a Scotsman who died in 1869. Graham has another interesting claim to fame as the discover of “Graham’s Salt,” which is actually a glass formed by Sodium Metaphosphate and may even have been the original solder glass. Graham is also said to have been a Presbyterian lay preacher, and is supposed to have used his own form of loose leaf notebook for preparing his sermons. On one occasion, he was preaching on Creation and was just at the end of one page as he was declaiming “And Eve said to Adam.” He turned over the page, looked puzzled, hesitated, then while looking down at his notes, repeated, “And Eve said to Adam—there seems to be a leaf missing.”


I have left till last my own favourite Herbert Mcleod (1841-1923), a Scottish Physical Chemist. There is probably no other glass instrument which compares with McLeod’s gauge for having so many “improvements” designed for it. The journals and abstracts are full of papers with titles such as “An improved design of McLeod gauge for measuring the internal measuring the internal pressure of whiskey kettles.” Yet, the old original has not altered in any important respect, and is still the gauge used to calibrate almost all other vacuum gauges. McLeod was professor of Physical Chemistry at several universities and was elected to membership in the Royal Society. The paper in which he introduced his “Apparatus for measurement of low pressures of gas” was delivered to the London Physical Society in 1874 and published in the Philosophical Magazine. I was fascinated to find that the original design incorporation a conical ground joint and also a ground ball joint, and this was in 1874! McLeod gives clear instructions for making the ball joint while a footnote contains a claim by a Dr. Sprengal that the conical joint should have been called a Sprengel Joint and cites a prior publication as proof.
It only remains now for me to express the hope that this look into the past has entertained you, and that it will perhaps give you a little more fuel for those interminable “consultations” which fall to the lot of every glassblower. At least, you will know a few more names to drop.

 

 

NMR tubes are not 'analytically clean' when delivered to you


NMR-010: Proper Cleaning Procedures for NMR Sample Tubes


So if your NMR samples require scrupulously clean glass, follow the procedures below for Difficult Cleaning Problems to assure your sample purity is never jeopardized. Since NMR tubes are formed over a metal mandrel and certain organic lubricants are used, these cleaning steps will assure that any trace organic or inorganic residues from these procedures is removed.
When you invest in high quality precision NMR Sample Tubes, you expect high resolution and sensitivity. Proper cleaning procedures can help you preserve the quality of your investment. Since the purpose of an NMR Sample Tube is to confine a liquid sample in a perfectly cylindrical volume within the spectrometer probe, the degree to which the tube accomplishes this determines the quality of the sample tube. Improper cleaning can damage NMR tubes and reduce your apparent spectrometer performance.
You should never use a brush or other abrasive materials to clean NMR tubes. Scratches on the inside surface of the tube allow a portion of the sample to extend beyond the perfect cylinder defined by the NMR tube. Because the portion of your sample which fills a scratch on the inner surface of a tube experiences a different magnetic field than the rest of the sample, lines will broaden and resolution will deteriorate when you use scratched tubes. And you'll see a reduction in apparent spectrometer performance, unless you reshim your spectrometer for each sample. That's a tedious procedure your investment in high quality tubes was designed to eliminate to begin with.
Proper cleaning of NMR tubes can be easy or difficult, depending on your sample. We'll start with simple cleaning situations and move to the harder cleaning problems. Because even difficult cleaning procedures end with a proper rinsing, explained under Simples Cleaning of NMR Tubes, you should be familiar with both cleaning procedures.

Simple Cleaning of NMR Tubes


When cleaning your NMR tubes is as simple as rinsing the tube with water or an organic solvent, you can rinse them one at a time. Your main concerns, then, are what to do with the rinsate. And, if you're using Acetone, also preventing dermatitis that results when oils are removed from your skin by this potent solvent.
If you rinse a lot of tubes, there are apparatuses available that will make your job much simpler. Tube washers, listed in the WILMAD NMR Catalog as Solvent Jet Cleaners, provide an easy way to clean either one or five tubes at a time. Using a vacuum flask and aspirator, solvent recovery is simple. And your hands won't be so easily dried out by solvents, either. A final rinse with Acetone is frequently used to remove the last organic contents from the tube. When your sample is to be dissolved in water or D2O, a final rinse with distilled water is usually adequate. You may want to take steps to remove traces of water from the surface of the tube. Follow the procedures for deuterium exchange, below.


Difficult Cleaning Problems


Tubes left with samples in them for a period of time frequently present a more challenging cleaning problem. Sample degradation or precipitation can cause material to adhere to the inner walls of the tube. Rinsing the tube doesn't always remove this adhered material. So WILMAD recommends using strong mineral acids such a concentrated or, in severe cases, fuming Nitric Acid soaks of 1-3 days, as needed. Nitric Acid can oxidize many organic chemicals and dissolves most inorganic materials, as well. WILMAD doesn't recommend using Chromic Acid, since residual Chromium can often adversely affect NMR experiments. Chromic Acid, while a stronger oxidizer, can leave paramagnetic Chromium VI behind, which can be removed only with repeated soaks with Nitric Acid. Copious rinsing of NMR tubes washed in acids is required to assure removal of residual acids. A final rinse with distilled water or Acetone is also appropriate.
Tubes which contained polymeric samples can be even more difficult to clean. When the polymers are natural products, like proteins and polysaccharides, strong acid soaks will usually be sufficient. However, when dealing with synthetic polymers, the challenge is more severe, since many polymers are inert to acids or insoluble in organic solvents by design.
Although polymers may not readily dissolve in solvents, it may be possible to soften them by soaking the tubes in a solvent that swells the polymer. Then a pipe cleaner might be sufficient to remove the softened material. It may take some experimentation to find the solvent combination that works best with your polymer system.
Agitation in an Ultrasonic bath with an appropriate solvent can also help dislodge stubborn sample residues. However, you should take precautions to assure that NMR tubes don't touch, since contact and vibrations can fracture delicate thin wall tubes. WILMAD offers a special tube rack for use in its Ultrasonic bath that prevents such destructive contact between tubes.

Removing Water from NMR Tubes


Drying tubes at elevated temperatures can reshape and ruin precision NMR tubes. If you dry tubes in an oven, WILMAD recommends placing tubes on a perfectly flat tray at 125° C for only 30-45 minutes. Better is the use of a vacuum oven that will remove water at lower temperatures. In a flat position, tubes that do reshape could be out-of-round and may not fit the spinner turbine as well. But they'll not affect the spectrometer probe adversely. Tubes placed in an oven in a beaker, flask, or tube rack can bend, increasing Camber (lack of straightness)1. Bent tubes may still fit the spinner turbine, but can damage or break the NMR probe insert, a costly repair with many probes.
But even drying at high temperatures doesn't remove water chemisorbed to the surface of the tube. Thus, the preferred method of water removal is chemical, not physical, treatment. In most cases, it is the protic content of water that must be avoided. So WILMAD recom-mends exchanging the protons of chemisorbed water with a deuterated solvent such as D2O prior to a short drying period in the oven. A bottle of D2O that isn't being used any longer is perfect for this purpose.
When water chemically degrades your samples, then removal of water is essential. Here, reaction of the water with a hydride solution can be used, with caution. After rinsing the hydride solution, a final rinse with very dry Acetone can be used to remove rinse solvent prior to oven drying. Cap tubes promptly to avoid absorption of moisture when removing dry tubes from the oven.

 

Unbreakable Glass
Chemists Steal Engineering Tricks from Sponges

Sponges are the homes of colonies of tiny marine animals, and wonders of miniaturized engineering. They employ complex structural arrangements, the strongest glasses known to man, and even microscopic fiber optics that glow in the dark. Scientists are trying to figure how to reproduce some of their tricks, such as producing glass at low temperatures.

Science behind the news is funded by a generous grant from the NSF

BACKGROUND: Bell Labs researchers have discovered that a sea organism known as the glass sponge uses basic principles much like those found in mechanical engineering textbooks to reinforce its seemingly delicate and brittle structure. Its architecture calls to mind the Eiffel Tower in Paris. Studying such creatures could lead to new concepts in materials science and engineering design.

ABOUT THE GLASS SPONGE: Unlike the squishy, manmade sponges we see all the time in our daily lives, sponges are an ancient group of animals whose presence in the fossil record goes back more than half a billion years. Sponges may be groups of collaborating individual cells rather than one unified animal, since they don't form tissues. This means they don't have hearts, lungs or other organs. But they are capable of creating some of the most complex and diverse systems of skeletons known in nature.

The glass sponge is made entirely of glass, spun into delicate fibers. It can even emit light despite the darkness of deep sea levels, thanks to the presence of fluorescent bacteria embedded in its structure. The intricate glass cages of the sponge have at least seven levels of structural organization. The creatures use fiber-reinforced cements, beams of bundled fibers, and diagonal reinforcement beams running at 45-degree angles to achieve maximum strength and stability. The glass beams, which resemble small needles, are made of alternating layers of glass and glue; the glue between each glass layer prevents cracks from spreading from one layer to the next. Wherever the beams intersect, more glue is added to toughen the connection.

WHAT WE COULD LEARN: By studying the glass sponge, scientists could learn how to create a strong material out of something that seems to be frail. It may also hold the secret to making glass at room temperature, instead of the extremely high temperatures required to do so today. Researchers believe that the individual glass fibers in the sponge are formed by a protein at the center of each glass filament.

The American Society of Civil Engineers contributed to the information contained in the TV portion of this report.

 

American Society of Civil Engineers
1801 Alexander Bell Drive
Reston, VA 20191-4400
Tel: 1-800-548-2723

 

 

Ten Do’s and Don’ts for Vacuum Systems


1. Never assemble glassware to lateral bars on your racks. Instead, use vertical bars to hold the finger clamps supporting your manifold and traps.


2. When starting-up a new vacuum line or one that has been exposed to air, it is best not to overfill the dewar. New or exposed systems have considerable amounts of water that is adsorbed in the glass. Thus, it is best to fill your trap-dewars to about 1/3 capacity and wait another half-hour or so until you fill the dewar all the way to the top. This avoids pressure spikes that occur when the liquid N2 boils-off and the condensate is collected too high in the trap.


3. Never use cryogenic traps on a leaking vacuum system. Oxygen and other materials can be trapped as a solid. Which in turn can clog the vacuum throughput and present catastrophic conditions from pressure build up as the solid melts to gas and increases volumetric pressures by factors of x600 or greater.


4. Restrict the use of silicone greases to traps only and avoid using the substance on adapter joints, stopcocks and orings. Silicone grease has a very short life span* and tends to polymerize through out a vacuum system. This makes cleaning a system very difficult when it comes to repairs. In addition silicon dust can cause sensitive electronic equipment to fail. Instead, use Apezion M grease for joints and orings and use Apezion N for glass stopcocks. Both have longer lasting properties, the latter is more expensive but provides a lubricant for rotating stopcock plugs.


5. If you frequently empty traps, silicone grease is an economic alternative. However, users should remove old grease and apply a new coating as often as possible. This will help avoid having your glass joints becoming permanently seized together.


6. When cleaning glassware in a base-bath, never soak joints that are connected together. Base baths can chemically fuse the two inter-locking pieces into one permanent piece.


7. When shutting down a system, always vent your traps before you turn-off your mechanical pump. This will avoid the back-streaming of pump oil into your system and allow the volatiles in your trap to boil-off without dangerous pressure build-up.


8. Hi-vacuum glass stopcocks should always have indexed numbers that match the plug to the barrel. These parts should not be interchanged.


9. Tygon and rubber hose tend to weld onto glass. To avoid accidents consider hose adapters that allow you to attach a hose to removable glass components otherwise always use razor blades to cut away old hoses.


10. Glass breaks only when two combined effects take place: Force & Flaws. It is important to always consider ways to reduce these effects. Over time flaws are inevitable. So use extra care on older glassware.

 


* Dow Corning silicone grease has a product shelf-life (in the tube) of about 18 months. When exposed to light or vacuum the grease can degrade in about two-weeks.

 

 

 

UNDERSTANDING GLASS COMPATIBILITY
(Warm Glass Co.)

Bullseye and Moretti glass types are not usually used in research efforts, however the article explains the subject well and in theory is similar to that of all glasses.


To better understand compatibility, lets consider what happens when glass gets heated in a kiln. Like many other substances, glass expands when it gets hot and contracts when it cools. This change in density, which occurs at the molecular level, can be measured in a laboratory. A typical one inch piece of Bullseye brand glass, for example, will expand 0.0000090 inches for each 1 degree Centigrade (about 1.8 degrees Fahrenheit) increase in temperature. Thats nine-millionths of an inch!
This rate, which is commonly known as the Coefficient of Expansion (COE), is usually expressed as a whole number, rather than as a long decimal figure. Most Bullseye glass, for example, is said to have a Coefficient of Expansion of 90, and you will often hear glass artists refer to it as COE90 glass. Spectrum, another common glass, has a COE of around 96, while Cornings Pyrex glassware has a 32 COE. Standard window glass, referred to as "float" glass by the glassmaking community, has a COE that is usually around 84-87, while Effetre (Moretti) glass, commonly used for lampworking, has a 104 COE.

These differences in expansion and contraction may not sound like much, but they are very significant on the molecular level. A 10 inch length of Bullseye glass, for example, will shrink about 0.046 inches (about 1 mm) in cooling from around 950 degrees Fahrenheit to room temperature. By contrast, a 10-inch piece of Spectrum glass will shrink about 0.049 inches over the same temperature range. That difference - .003, or three thousandths of an inch - sounds trivial, but its enough to ensure that you cant fuse Bullseye and Spectrum together.


Two glasses with considerably different COEs are said to be incompatible. They cannot be fused together and should be kept in separate areas of the glass studio to prevent their accidentally becoming intermingled. This is especially critical because you cant always tell incompatible glasses just by sight. In the example below, Bullseye (90COE) and Spectrum (96 COE) glass has been fused together. All looks fine to the naked eye, but viewing the glass with a polarized film shows the underlying stress.
You can sometimes get away with using two different glasses where the COE is only one or two apart (say, a 90 with a 91), but not always. Sometimes even two glasses with the same Coefficient of Expansion can not be fused together. Thats because the laboratory test that determines COE takes place at a different temperature than the one the warm glass artist often uses.


There are really only two ways to know if your glass is compatible:

1. Use glass that has already been "Tested Compatible" by the manufacturer.
2. Have the compatibility factor tested.

 

 



Science & Technology (no pub)
Feature: Space glass cracks earthly limits

By LIDIA WASOWICZ
UPI Senior Science Writer

Results from space-bound experiments unencumbered by gravity are crystallizing the wondrous possibilities of creating glass that breaks the mold in ways not thought possible on Earth. Space glass could revolutionize fiber optics and other terrestrial technologies and even serve as construction material for erecting structures on other planets. Trailblazers on the cutting-edge of glassmaking envision extraordinarily transparent glass fibers stretching for thousands of miles across continents or super-strong glass glue made of "moon dust" that can cement walls, floors and roads on extraterrestrial worlds. The pioneering craftsmen think they can bring seemingly pie-in-the-sky notions down to Earth. Already, National Aeronautics and Space Administration researchers who have dabbled in making glass in the weightlessness of space have discovered their creation is endowed with some remarkable properties. For one, it has the pristine purity of an object untainted by touch because it lacks the need for a container that must hold the molten precursor of glass -- called the melts -- back on the ground.

"At high temperatures, these glass melts are very corrosive toward any known container," explained Delbert Day, Curators' Professor of Ceramic Engineering and senior research investigator in the Graduate Center for Materials Research at the University of Missouri, Rolla. Day conducted the first U.S. glass melting experiments in near-weightlessness aboard the space shuttle in 1983. As it eats away at the confining crucible, the melt -- and thus the glass -- becomes contaminated by the dissolving particles. In contrast, in gravity-free experiments, the molten glass stayed suspended inside a hot furnace simply by the pressure of sound waves emitted by a special device called an acoustic levitator. Like a trick out of a magician's book of floating gimmicks, acoustic levitation can position and move a tiny sample -- a mere fraction of an inch (a few millimeters) across -- in mid-air. The force from the sound waves suffices to suspend, place and manipulate the test target, eliminating the necessity for containers and the danger of contamination. "The great potential is that we will gain information from experiments in space which will let us better understand materials that we already are making on Earth so that we can make them faster, better and cheaper," predicted Day, whose credits as an inventor include thinner-than-a-human hair glass spheres that deliver high doses of cancer-shattering radiation directly to a disease-riddled organ or tissue. With the newfound availability of space as a one-of-a-kind laboratory, the sky could be the limit in glass research, scientists told United Press International.

"We can't even comprehend what we are missing," Day marveled. For example, his crystal ball points to glass as a major player in the future settling of other worlds, if such comes to pass. "If and when we colonize another planet, we will need to use as much of the material on the planet as possible since we can't transport all of the materials required from Earth," Day projected. Glass made of "moon dust" and native soils melted by solar energy could provide the construction material for floors and walls, he envisioned. "Molten glass could be used to glue the naturally occurring rocks together in much the same way that cement is now used to glue the rocks (aggregate) together to build roads and buildings," Day added. "Might sound a little far-fetched, but everything about living on another planet will be far-fetched." Closer to home, space glass also could have a life-altering impact, scientists proposed. "The key to producing the highly transparent glass fibers used for optical communication, which are revolutionizing our world -- we are now rewiring the world a second time, the first was with copper wires and the second is with glass fibers -- is to develop an entirely new method for melting high purity silica glasses," Day told UPI. "The main idea at this time is to use the information gained from experiments in space to improve our manufacture of glass made on Earth."

On Earth or beyond it, glass -- be it of the ordinary variety used in windows and bottles or of a more exotic form that facilitates optical communication -- follows a fundamental formula. The age-old recipe calls for combining such materials as sand, limestone and soda, boiling the mixture until it glows red-hot, then cooling the incandescent goop with utmost care to avoid the formation of crystals, which would ruin the desired effect. Glass -- a solid with an amorphous internal structure -- can form only if the melt cools quickly enough to preclude the atoms from hooking up into the patterns that typify crystals. When all goes according to plan, the result is a hard, brittle, usually clear or translucent substance that can stand up to wind, rain or sun and serve an ever-expanding range of pragmatic and cosmetic purposes. "While glass is one of the oldest materials made by man (it is thought to have been created by the Phoenicians around 3000 B.C.), we are still discovering new uses and new glasses all the time," Day pointed out. For example, he continued, there are "fibers for optical communication, oven (thermal shock) proof chemical ware and dishes, new glass which barely changes dimensions when heated/cooled that is now used in the Hubble Space Telescope (which couldn't explore the universe without those glass lenses), glass microspheres for treating patients with cancer, et cetera."

Most of the familiar types of glass blend silica obtained from beds of fine sand or from pulverized sandstone, an alkali to lower the melting point, usually a form of soda or, for finer glass, potash, lime as a stabilizer and cullet, or waste glass, to help the mixture melt. Scientists with sights set on more exotic applications, however, strive to break out of the traditional mold. If, as the initial results indicate and Day is convinced, glass melted in zero gravity resists crystallization, then setting up shop in space -- either as a full-force factory or even as an occasional testing ground -- could forever transform glassmaking, scientists said. "Glasses have a wide use in our everyday life, and their use would be even greater if we were able to prevent formation of crystals," noted Tihana Fuss, a doctoral candidate from Zagreb, Croatia, who works with Day's group. "It appears that melting glass in space does exactly that." Taking gravity out of glassmaking could have a two-fold benefit, scientists speculated. "This would not only mean that we would be able to improve properties of present commercially used glasses, but also that we could make new types of glasses," Fuss told UPI. Particularly intriguing to space researchers -- and of exceptional potential value to the fiber optics industry -- is an exotic glass made of metal called ZBLAN, an appellation derived from the chemical names of its components. The blend of fluorine and the metals zirconium, barium, lanthanum, aluminum and sodium (Zr, Ba, La, Al, Na) is 100 times more sheer than silica-based glass. "A fluoride fiber would be so transparent, light shone into one end, say, in New York City, could be seen at the other end as far away as Paris," Day remarked. "With silicon glass fibers, the light signal degrades along the way." To their dismay, scientists found fluoride fibers are difficult to produce on Earth, where the melts tend to crystallize before glass can form. But space-based processing promises to offer tips on overcoming this obstacle, researchers said. In fact, tests conducted in a KC-135, a workhorse four-engine jet aircraft that provides short bursts of near-zero gravity interspersed with periods of high gravity, showed thin fibers of the exotic glass are clearer when made in near-weightlessness than back on the gravity-saddled ground, noted Dennis Tucker, a physicist in the Space Sciences Laboratory of NASA's Marshall Space Flight Center in Huntsville, Ala.

ZBLAN glass fibers carry enormous commercial potential -- to the tune of $2.5 billion a year by some estimates -- for advanced communications, medical and manufacturing technologies using lasers. The biggest payoff could be in optical fiber communications where glass threads carry millions of telephone conversations and video and computer data. Telecommunications companies are investing heavily in optical fiber systems, including a "glass necklace" that will encircle the world, replacing transoceanic cables and eventually entering neighborhood communications. Day points to one crucial missing link that remains: comparison of glasses processed in space and on Earth. He hopes to fill in the blank, and confirm his theory of the superiority of space-based glassmaking, with the next set of experiments -- aboard the International Space Station. "We will measure the number and size of crystals in the glass (produced in space) and compare those numbers with identical glass samples processed on Earth," Day explained. "These data should confirm that glass formation is improved in space." Although the Feb. 1 disintegration of the space shuttle Columbia and the ensuing uncertainty about the future of the shuttle program have played havoc with time schedules, Day and company hope to be conducting their space tests within three years. The realization of practical applications for space-based glass research is still several years away, scientists cautioned. "It depends obviously on funding to perform the basic research, then interest from private companies who see a benefit from producing glass in space for use on Earth," said Tucker, who is working with a private company on the design of an automated fiber producing facility that uses robotics to perform human functions. The plan is to launch the facility into low-Earth orbit and deploy it to produce miles of glass fiber, including ZBLAN, then have it land by parachute and repeat the cycle, Tucker said.Day hopes eventually to bring the lessons learned from space down to Earth.

"(My) ultimate goal," he said, "is to gain knowledge which will improve our life on Earth and which might contribute to our effort and plans to explore the universe."

 

 

 


Chemical & Engineering News
January 16, 2006

Glassblowing-An Essential Craft
Despite the declining use of glass, glassblowers remain vital to science and medicine
Rachel Petkewich



On a steamy day last August, a group of chemists from Bristol-Myers Squibb visited Vineland, N.J., to tour Chemglass, one of the largest producers of scientific glassware. Even with 30-foot ceilings, the 85,000-sq-ft main building of the plant sweltered and buzzed with activity. More than 70 glassblowers peered through safety glasses, concentrating on their individual tasks. One chemist murmured, "I thought all this stuff was made by a machine."

Although machines can fabricate basic labware such as beakers and Erlenmeyer flasks, scientific glassware requires skilled handwork. Crafting just the basic shape for a custom 72-L reaction vessel, for example, requires a team of eight. Many more skilled hands contribute to the finished piece.
Glassblowers used to be fixtures in the chemistry departments of large research universities and in the workshops of industrial and government research facilities. Declining demand for glassware caused by alternative materials and new techniques has reduced the number of people skilled in the craft and the number of job opportunities.
But because scientific research and medical innovation cannot do without glassware, glassblowers will never disappear completely. Despite having far fewer practitioners now, scientific glassblowing continues to attract new people who, after years of training, find ways to survive and even thrive.

Hot, viscous glass waits for no one. Glassblowers acquire skills by learning from a family member, on the job, through an apprenticeship, or by taking courses.
A certain amount of natural ability is required, including dexterity, says Anthony Tamburelli, a native of Naples, Italy, who learned the craft in 1955 at Kontes, another large New Jersey scientific glassware company, and who has trained many glassblowers at Quark Glass, a small production facility in Vineland. Other physical demands include the ability to withstand the year-round, intense heat that comes with working in a room Government-recognized apprenticeships require up to 8,000 logged hours or about four years of work, after which one becomes a journeyman. Master glassblowers have decades of experience in addition to inherent talent.
Ready for the heat, Tara DiCinque applied for an apprentice position in the lamp room at Ace Glass, also in Vineland. She had dabbled with glass art, but the precision of scientific glassblowing drew her in. After six years with Ace doing various tasks including washing and packing glassware, she had the opportunity to become an apprentice. Just last month, two years after she started her apprenticeship, she hit the 5,500-hour mark. She expects to complete her 7,000 hours required by New Jersey within a year.
Practice is the best way to master specialties such as medical glassblowing, which includes making molds for devices such as stents and anatomically correct models of human body parts. Wade Martindale began training at Farlow's Scientific Glassblowing at age 13. He came from Canada to work summers, and he's been working there full-time for 11 years. "Everything has been on-the-job training and just working through the ranks," he says. "Now I'm almost exclusively doing heart models because there are so many orders."

Gary T. Farlow, who trained as an art glassblower in the mid-1970s, founded Farlow's, located in Grass Valley, Calif. He began his career by making little animals and ships, and then he learned about laser components and glass-to-metal seals for X-ray tubes. Eventually, he started his own company and got involved with medical glassblowing. He has hired people with various skill levels, from those who have never touched a torch to master glassblowers. "Most people have just fallen in love with the work, stayed on, and advanced in it," he says. Some glassblowers earn four-year degrees in glass arts or ceramics. Many go to Salem Community College in Carney's Point, N.J., the only school in the U.S. that grants degrees in scientific glass technology. The program began in 1959. Its graduates are sought for glassblowing positions in production, university labs, and commercial R&D work.

At Salem, students can get an associate's degree in two years. They take classes in English and math, as well as chemistry, physics, and technical drawing. "We teach them to think, not just to manipulate glass," says Don Hodgkins, a Salem graduate and the instructional chair who teaches all of the scientific glass classes. But most of the courses involve "making actual scientific products," he adds.
Salem's curriculum focuses on flamework, which requires skills in manipulating intermediate forms of glassware, such as glass tubing, with torches at benches and rotating stands called lathes. In the first year, students learn basic skills and fabricate simple apparatus. Some of the products fabricated during the second year include reaction flasks, condensers, bump traps for rotary evaporators, and vacuum manifolds.
Students spend 10-20 hours per week working on projects in Salem's state-of-the-art Glass Center. Six hours are earmarked for class time, and the rest are devoted to working on technical skills with a wide variety of equipment during open lab. In class, students analyze a technical drawing, watch the instructor's demonstration, and then reproduce that piece. During class, Hodgkins moves from student to student, answering questions and providing tips that he has learned from 25 years of experience in production custom shops and research facilities.

Many working glassblowers from near and far have spent a year or two at Salem. Current students range in age from 18 to 40. "People from all around the world come to school here, across the street from where I grew up," says Brian Rainear, who graduated 19 years ago from Salem and is the foreman in the lathe room at Ace Glass. Although a couple of universities had offered him golf scholarships after high school, he followed his family's tradition and pursued scientific glassblowing. He says the knowledge he gained in chemistry and physics classes helped him understand what chemists need when they request custom work.
Sam Conterato came to Salem from farther away. Halfway through a bachelor's degree in management information systems at the University of Wisconsin, Eau Claire, he met a member of the chemistry department, became interested in scientific glass, started looking for a new program, and transferred to Salem. Scientific glassblowing, he says, will provide him stable and reliable work in industry. To pay for school and to get more experience while in New Jersey, he is working at Glastron, a manufacturer of specialized and biomedical glassware in Vineland. He's also pursuing a degree in glass art through a glass arts program that Salem offers.
Dipogiso White came from farther still: Botswana. "People don't know glassblowing in my country," he says. With a city and guilds certificate in laboratory technology from the University of Botswana, he worked for a university in Gabarone, the country's capital. The government of Botswana is building a science and technology university and will need a glassblower; the hospitals need glass, too, he says. The only other person in Botswana who knows scientific glassblowing is Zambian and ready to retire, he explains. He plans on returning to his job in Botswana after graduating.

Prior to 1915, scientific glassware was manufactured primarily in Germany. When World War I cut U.S. access to those products, Corning stepped in with Pyrex glassware, says Stuart Sammis, historian for the firm, headquartered in upstate New York.
Early in the 20th century, southern New Jersey became an epicenter for a wide variety of glass products because of its proximity to a high-grade raw material called silica sand. The area still has the highest concentration of scientific glass companies in the world. Salem, nestled in the area, enjoys strong support from the scientific glass companies. According to Hodgkins, those companies donate 95% of the glass materials that Salem students use for assignments.
" Twenty years ago, chemistry was 90% of the scientific glassblower's work. Think of all the joints, stopcocks, and valves and ball sockets that chemists use on their systems," says Michael Souza, Princeton University's glassblower. He started his career in glassblowing in 1973. At the time, the university employed three glassblowers just to keep up with orders and repairs for flasks and columns. Now, Souza says, "about 20% of my work comes from chemistry. The rest of it comes from physics, materials sciences, geosciences." Other glassblowers receive projects from various disciplines in engineering and biological sciences, as well as from medical schools.
Four main advances in science and medicine have reduced demand for glassware. First, technology and instrumentation cut out a lot of wet chemistry. Second, the trend in microscale operations necessitated the use of smaller glassware. Third, large-scale distillations and separations moved to metal apparatus to reduce injury from accidents. And fourth, sophisticated materials and polymers became popular in biological and medical applications.
In the 1980s, about 1,500 people attended the national meetings of the American Scientific Glassblowers Society, according to David Surdam, vice president of Chemglass, his family's business, and vice chair of the Delaware Section of ASGS. "Now, you are lucky if you have 500, because a lot of glassblowers have lost their jobs through attrition," he says.

Glassblowing must be a labor of love, because the pay is modest. Apprentices usually start at $10-$12 per hour, masters can command $30 per hour or more, and the rates for journeymen fall in between. Some university glassblowers, however, can earn up to $90,000 per year.
Job openings tie to the ebb and flow of basic research funding. Souza says the work is "very hard for the young person to get into." Salem's Hodgkins, on the other hand, points out that researchers in many fields seek glassblowers to create custom glassware and apparatus, pieces that cannot be made by a machine. Many highly skilled glassblowers are now reaching retirement age, he adds.

Still, scientific glassblowing is in decline. Production companies stay afloat through strategies akin to those taken by other manufacturing industries, including partnering, diversifying product lines, or focusing on a niche. Chemglass, for example, is expanding its scientific catalog and looking into other markets, including replacement joints and bone pins and screws. "Companies are making them out of composites now, and we have a machine shop that is capable of doing that," Surdam explains.
Small manufacturers are a good fit for the custom work niche. Doug Riley, president of Quark, a small company, says, "We have heard that we have delivered the piece before a large company has gotten a quote back." Quark's salespeople pick up and deliver pieces to labs when possible to avoid shipping delays.
Large consumers of scientific glassware, such as pharmaceutical companies, are opting to dispense with an on-site glassblower in favor of buying disposable products from glass manufacturers or outsourcing to small, local "contract shops." These one- or two-person operations exist all over the country; some fare better than others. In some cases, a company outsources to its former glassblower.

" At one point, P&G had about six glassblowers at a shop here in Cincinnati," says Rick Ponton, one of two glassblowers worldwide at Procter & Gamble. As they retired, however, they were not replaced. P&G tried to get by with only one glassblower but couldn't, he adds.
Glassblowers and their craft will never disappear. Keeping glassblowers in-house at any research facility offers two benefits, Ponton says. First, chemists have someone they can consult directly, an especially important capability in moments of crisis, such as when a vacuum line pops mid-experiment. Researchers can have some problems solved within an hour instead of delaying experiments for weeks while replacement glassware is en route. Second, maintaining an on-site glass shop may in fact be a bargain. "I charge my labor hours, and that's it," he says. "Something that would be in a catalog for $200, I can probably get to my customers for $50, because I don't make 35-60% profit like glass manufacturers."

P&G once considered outsourcing all its glassblowing needs, as it had done with its electrical and plumbing services, Ponton says. "But the chemists here stood up for us and fought for us." He adds, "I hear from a lot of glassblowers in academia, and they are always worried about that red pen."
Survival in the era of outsourcing weighs heavily on many university glassblowers. Bringing in work from outside is one survival strategy, but there are a few who don't need to. For example, Kevin Teaford, the glassblower at the University of Utah, is the only glassblower in the state. He has plenty to keep him busy, he says. Fourteen years ago, he switched from law enforcement to train in several places as a scientific and medical glassblowing apprentice.
Specialization is another strategy. Princeton's Souza, for example, is sought after because he works with aluminosilicate, a type of glass popular with physicists investigating tiny particles and light gases that can pass through the standard borosilicate and even more expensive quartz glass. "Aluminosilicate is a nightmare to work with, and almost every other glassblower hates it," he says. "So now I get stuff from all over the country and parts of the world." He estimates that 10-15% of his billable work comes from other universities and national research facilities.

At universities, glass shops, like machine shops and electronics shops, are part of the research team, and all are threatened by funding cuts. "But to be competitive in the modern research world you need to have certain facilities," says Patrick H. Vaccaro, a professor of physical chemistry at Yale University and one of five members of a search committee that selected a new glassblower last summer. "In many ways, universities have to become a little bit creative in what they think a glassblower should be doing."
Yale's new glassblower, Daryl Smith, is housed in the chemistry department; however, faculty in physics, engineering, molecular biology, and the medical school seek him out. In addition, as a former Salem instructional chair, he plans to teach some basic bending, sealing, and repair techniques to chemistry graduate students, who can apply them in the lab. That group still goes through plenty of glass.
Scientific glassblowers are dedicated, and despite geographic isolation, remain a tight community via Web forums. Collaboration with researchers intrigues them. "I think this is a great job because you get to see the research, but you don't have to do it," says Sally Prasch, a glassblower at Syracuse University who also runs her own glass shop in Massachusetts and has worked for AT&T.

" There is a satisfaction I get from my work that I can't imagine I would find anywhere else," Souza says.

 

A Bit About Glass
(liquid or solid?)

From THE SCORE (# 40), published by Spectrum Glass Company, Inc.

Has anyone ever told you that glass is actually a liquid? That, ever so slowly, everything made of glass is actually flowing, and will eventually reduce itself to a glossy puddle on some futuristic landscape? It's not an uncommon tale, even though it's absolute horsepucky.

Some glass buffs think the notion of glass as a liquid got started in Europe a century or so ago, when very old sheet glass was removed from very old buildings under renovation. The workers might have noticed that the sheets were much thicker on one end than the other, and that the thicker end was always down. Drawn by centuries of gravitational pull, they speculated, the bottoms of the windows had become thicker than the tops. Since people were already accustomed to fairly uniform sheet glass by that time, it's no surprise that the ancient hand-blown sheets raised some eyebrows, and possibly, the faulty conjecture.

A more likely explanation for the misconception arises from the definitions of "liquid" and "solid." The truth is, glass exhibits characteristics of each. Webster defines "liquid" as "a substance which exhibits a readiness to flow." Of a "solid" the dictionary says: "of definite shape and volume; not liquid or gas." Clearly, what we call "glass" better fits the latter than the former. But science doesn't look to Webster to draw their distinctions. Science-types will tell you that a material is a solid when its molecules are motionless and lined up in flawless geometric fashion, in perfect little rows and columns, like thousands of tiny soldiers at attention. This molecular configuration is called "crystalline". A liquid, on the other hand, is quite the opposite. Liquid molecules are in a constant state of movement and entirely random in their configuration. Scientifically, then, cold glass is neither liquid nor solid, because its molecules are motionless (like a solid) but random in configuration (like a liquid). This structure is characteristic of all vitreous (glassy) substances.

Many materials, like water and iron, are common in both liquid and solid states. At any given moment, their state depends on their temperature. Water molecules are disorderly and mobile only to a point, which is thirty-two degrees Fahrenheit. There, the water molecules "crystallize" - they line up in perfect lattice-like order and cease moving altogether, until the warmer side of thirty-two shines once again. The liquid has become a solid.

Thirty-two is said to be the "freezing point" of water (or the "melting point", depending on which direction temperature is moving). But this is a "point"only in temperature, not in time. When water reaches thirty-two degrees, it stays at thirty-two degrees until crystallization is complete. This may take a split second (a snowflake) or a great deal of time (Lake Omygoochie). Only when every molecule has taken its place in the lattice and come to a standstill will the temperature continue its decline.

One of the most fascinating things about vitreous substances is the conspicuous absence of any freezing point or melting point. There is no "point" in temperature where glass naturally maintains itself while its molecules reconfigure. As temperature decreases, the free-flowing molecules in molten glass simply move more and more slowly, until they are no longer able to move at all. But theymaintain their random configuration; crystallization does not occur.

If, on the other hand, we hold glass at a given temperature for a long enough time, crystallization, to some degree, will take place. The crystallized areas will no longer be glass, of course, because lack of crystallization is how we define glass. The crystallized areas are non-glass; they are de-vitreous -- devitrification has occurred.

Think about what happens as a piece of cold glass is heated. The randomly configured "frozen" molecules slowly begin to awaken and agitate. As the glass becomes warmer there's more freedom of movement. The higher the temperature, the faster and freer the molecules spin about. What is happening? In a practical sense, the glass is moving through different degrees of viscosity. From cold and hard it becomes warmer and softer, then pliable, then soft enough to slump under its own weight. Eventually it will puddle and finally, become liquidous. There are no such stages or degrees between water and ice; it's either one or the other. Such is the unique magic of vitreous substances.

Glass, then, is really neither a liquid nor a solid; it exhibits definite characteristics of each. In fact, some schools of thought find it more clear and convenient to classify matter into four states instead of the traditional three. So don't be surprised if your kids come home from school one day and tell you the Four states of Matter are liquid, solid, gas, and glass.

 

 


I am Glass
1940 BY GEORGE J. OVERMEYER

 

I am created of the admixture of Earth’s minerals, formed by the alchemy of time.
I am born transformed in the blasting heat of fiery furnace.

I am molten mass I am tediously fashioned by the hand of cunning Artisans - or fed into the maw of intricate machine.
I assume ten thousand hues of all the spectrum - either transparent, translucent or opaque - upon my maker’s will.

I can masquerade as ruby - emerald - topaz - moonstone: and all other priceless jewels of man.
But frivolous baubles are not my aspiration - I serve ten million purposes in as many places, forms and ways.


My duties are unnumbered - infinite: pay heed to my utility.
I admit the Heavenly light to hovel, palace or cathedral, and yet repel cold winter’s howling breath.

I faithfully project the light that warns great ships from shoal and concentrate the beam that guide swift vehicle through storm and gloom of night to bring the wayfarer safe home.
I visibly contain my master’s food - his drink - and countless other of his commodities; protecng them in transport and in the mart and home.

I form the glowing shell of bulb and tube to diffuse his artificial light - and to disseminate his advertising.
I am the walls of his abode, his office and his factory - and objects of utility and art in each of these.

I reflect his image - and mark the effects of time upon his person - sometimes I flatter but more often am critically severe.
I correct his impaired sight and thus bestow enjoyment of the printed word - and all of Nature’s beauties roundabout.

I magnify his minute, unseen enemies and thereby do I promote his health and happiness.
I form the gossamer thread from which is fashioned fine raiment - yet too the insulation of his dwelling
I reveal to him the mysteries of his Universe - carrying his vision to the illimitable reaches of the outer stars.

Through me he learned to chart the Firmament - to plot the orbits of the Planets and predict the courses of the Comets and Eclipses.
This knowledge I unfold is but the pledge of vaster knowledge as - step by step - I lead him to unexplored, immeasurable spaces.

For I am older than the pyramids yet newer than tomorrow’s unborn dawn - withal the marks of time affects me not - for I am ageless and retain my lustrous beauty permanently.
Some of my tasks I have recounted - but this is only the beginning; for those who made me and adapt me to their uses are men of vision - and together, and times unfolds, we will go far.

And so - in modesty I proclaim - I am Man’s invaluable and versatile servant - I AM GLASS.

 


One Way Mirrors/glass

Glass can be covered with a thin coat of silvering and then not covered with the paint used to make an opaque mirror. When this is done, the glass is said to be half-silvered or to be a one-way mirror or one-way glass. Because of these latter names, there are people who believe that a product exists which is always mirrored on one side and always clear on the other side, which is not true. The visibility through such a mirror/glass depends entirely on the lighting - those on the more brightly lit side will see the glass as a mirror and those on the darker side as a more or less transparent window. The silver surface (and reflection) take out much of the light passing through, so the view through the glass is always darkened. If there is any light on the dark side, then it is possible to make out what is going on there from the bright side. Even if the dark side is completely black, some light is present having come through the one-way. Because the reflection is less than perfect, with experience it is easy to spot that a piece of mirror is half-silvered. Normally, because of its expense and fragility, users installing half-silvered do not even disguise the small mirror as being a real mirror - the reflection merely prevents people from easily knowing whether someone is behind the view port. It is now much cheaper to use reflectorized plastic film such as is used on cars.

Front Surface Mirrors

Normally mirror silvering is applied to the back of the glass where it is protected from touching. It is further protected and enhanced by painting over the silvering with opaque paint that reduces further the light passing the silver coating, making the reflection brighter. When silvering is applied to the front of a mirror, it is normally very fragile - it will scratch easily and show fingerprints if touched and if wiped will show smear as tiny scratches, reducing the reflection. It is difficult to put a protective coating on the mirroring, it must be very thin and clear. However, there are uses for front surface mirrors because there is only one reflective surface. Glass makes a very smooth surface for a good mirror, better than metal. If silvering is on the back of the glass, there is some small reflection from the glass front surface and the double image is distortion. The most widely available front surface are the small mirrors sold for use in kaleidoscopes. Astronomical mirrors are front surface silvered and both curved and smaller flat mirrors are sold through astronomy supply firms.

 

 


Communicating with Glass Science

Cancer Treatment

A cancer treatment in which glass microspheres deliver radioactivity directly to diseased areas in the body is currently being tested. Canada already uses the treatment, which shows success for liver cancer, and may be appropriate for other cancers. The treatment is promising, because it replaces the need for external beam radiation, which can cause unnecessary damage to healthy surrounding tissues. In the treatment, 5-10 million glass micro-spheres, 1/3 the diameter of a human hair are injected into an artery. Don't worry - that's only a small fraction of a teaspoon, less than 1/10 cc. Too large to pass outside of the diseased liver, the spheres remain harmlessly in the organ even after their radioactivity has disappeared.

 

 

High-Tech Glass: Pure Material Made in Levitation Lab

An experiment originally designed to fly on the International Space Station (ISS) led a team of researchers to develop a completely new type of glass, a material formed while floating in mid-air in a NASA laboratory on Earth. Using static electricity fields to levitate the material, scientists were able to construct a pure glass, free of any contamination typically associated with containers. It could serve as the centerpiece for new medical and industrial lasers, as well as have broadband Internet applications.

"I think there's a lot of potential for this glass," said Rick Weber, director of the Glass Products Division of Containerless Research, Inc., which invented a whole family of the new transparent material. "We've got a wide composition field, so one [glass] can be tuned for a particular use." Weber told SPACE.com that new the glass is currently being put through its paces in several validation projects for applications in high-density lasers, and as the glass components for low-cost, compact broadband devices.

Levitating glass

The new material, known as REAl glass -- short for Rare Earth Aluminum oxide -- was first developed at NASA's Electrostatic Levitator (ESL) laboratory at Marshall Space Flight Center in Huntsville, Alabama. Scientists there routinely use static electricity to allow their experiments to defy gravity inside a vacuum chamber, then zap them with lasers to turn them into floating molten balls of material that can later cool without any interference from a crucible or container. "The ESL is a very pure way to look at what a material does," said Jan Rogers, a facility scientist for the ESL. "In an oven or container of any sort you have contact with the container wall, and at high temperatures a sample can interact with those walls, absorbing specks of dust and having a chemical reaction with the container." By melting and cooling a levitated material, scientists can understand not just its formation, but its inherent physical properties. Surface tensions keeps molten samples together which, when cool, coalesce into tiny spheres. At the most fundamental level, making REAl glass uses the same method used by glass-makers for centuries, namely mixing materials together, melting them, then cooling them into a solid. But its the levitation that gives REAl glass its kick. The process allowed researchers to imbue their glass with a number of attractive properties, such as chemical stability, infrared transmission and laser activity.

"Other glasses tend to have just one of those properties, and at least one weakness," Weber said. "They could be really good at infrared transmission, but dissolve in water so you wouldn't want a window made out of it." Laser applications are key for REAl glass, since the material could serve as the "gain medium," a component that amplifies light into a concentrated beam capable of cutting metal for car assembly or human tissue during surgery. REAl glass laser gain mediums could provide a range of available wavelengths to give surgeons more control of beam intensity, depending on tissue type and surgery, he added.

 

Consumer glass

Once Containerless Research scientists understood the basics of REAl glass formation, they were able to adapt the technology away from its dependency on electrostatic levitation. The step was a crucial one for commercial purposes, since NASA's ESL facility is only powerful enough to levitate tiny sample materials up to three millimeters wide and 70 milligrams in weight. "So we're not talking about golf balls and pineapples here," Weber said of the ESL's production capabilities. "For commercial purposes, we needed at least rods and plates of the glass." Weber's team was able to devise a small-scale production plan that uses platinum crucibles to melt REAl glass and cooling forms that shape into commercial rods and plates, all without taking away the materials positive properties.

 

A glassy side project

Containerless Research scientists did not originally seek to develop REAl glass outright when they approached NASA with a proposed space station experiment. That proposal, which used the Marshall lab as a proving ground before reaching the orbiting outpost, sought to explore the properties of molten oxides and aluminates. "Most of my customers are space flight candidates," said Rogers of the researchers who use the ESL facility. "Some of them have experiments for the ISS, where they would be using the next generation levitator." That instrument, an electromagnetic levitator for space-based material science studies, is being developed for the European Space Agency's Material Science Laboratory aboard the Columbis module of the ISS. The module was scheduled to be launched via space shuttle in October 2004, though NASA does not expect another shuttle flight until at least March 2005.

"When the appropriate instrumentation is available, we still hope to conduct that flight experiment," Weber said. Other scientists have used some form of levitation, though not exactly Weber's approach, for glass making, both on Earth and in space. Delbert Day, a NASA-funded researcher at the University of Missouri-Rolla, for example, used sound waves to levitate glass samples in order to study higher-quality glasses. He also designed microgravity experiments for the space shuttle.

 

 

Researchers: Evidence of ancient Egyptian glassmaking

 

What may be one of the earliest glassmaking sites in ancient Egypt has been uncovered in the eastern Nile Delta. Evidence at Qantir-Piramesses indicates that glass was made there out of raw materials as early as 1250 B.C., researchers from England and Germany report in Friday's issue of the journal Science. The reworking of already made glass into finished goods has been documented at ancient sites in the Middle East and Egypt, but the new report adds evidence for primary glass production at this location. Thilo Rehren of University College, London, and Edgar B. Pusch of Pelizaeus Museum in Hildesheim, Germany, report finding a large number of crucibles with remains of glass inside.

Glass was made using finely crushed quartz powder which was melted with other materials inside the ceramic crucibles, which then were broken to get the glass out, they reported. The glass ingots "would then have been transported to other, artistic workshops where they were re-melted and worked into objects," Pusch and Rehren reported. Much of the glass produced at Qantir-Piramesses was red, produced using copper in a complex process, and some of it was blue or colorless.A large shipment of glass ingots has been found in an ancient shipwreck off the coast of Turkey. The wreck predates the materials found at Qantir-Piramesses, but the ingots are similar in size and shape to the crucibles found at the Egyptian site.

Fragments of similar crucibles have also been found in Egypt at el-Amarna and Lisht, Rehren and Pusch noted. Caroline M. Jackson of the University of Sheffield in England called the new report "highly significant." Jackson, who was not part of the research team, said, "Rehren and Pusch convincingly show that the Egyptians were making their own glass in large, specialized facilities." In a commentary accompanying their report, Jackson says their analysis reinforces the role of glass in Egypt "as an elite material that was exported from Egypt to the Mediterranean world." Rehren and Pusch's research was funded by the German Research Council and the British Academy.

reference pasted as printed from CNN.com 6-16-05

 

 

 

 

History of Glass

Early Times | Middle Ages | Early American Glass | Modern Glass Making

Early Times.

Before people learned to make glass, they had found two forms of natural glass. When lightning strikes sand, the heat sometimes fuses the sand into long, slender glass tubes called fulgurites, which are commonly called petrified lightning. The terrific heat of a volcanic eruption also sometimes fuses rocks and sand into a glass called obsidian. In early times, people shaped obsidian into knives, arrowheads, jewelry, and money. We do not know exactly when, where, or how people first learned to make glass. It is generally believed that the first manufactured glass was in the form of a glaze on ceramic vessels, about 3000 B.C. The first glass vessels were produced about 1500 B.C. in Egypt and Mesopotamia. The glass industry was extremely successful for the next 300 years, and then declined. It was revived in Mesopotamia in the 700's B.C. and in Egypt in the 500's B.C. For the next 500 years, Egypt, Syria, and the other countries along the eastern shore of the Mediterranean Sea were glassmaking centers.

Early glassmaking was slow and costly, and it required hard work. Glass blowing and glass pressing were unknown, furnaces were small, the clay pots were of poor quality, and the heat was hardly sufficient for melting. But glassmakers eventually learned how to make colored glass jewelry, cosmetics cases, and tiny jugs and jars. People who could afford them—the priests and the ruling classes—considered glass objects as valuable as jewels. Soon merchants learned that wines, honey, and oils could be carried and preserved far better in glass than in wood or clay containers.

The blowpipe was invented about 30 B.C., probably along the eastern Mediterranean coast. This invention made glass production easier, faster, and cheaper. As a result, glass became available to the common people for the first time. Glass manufacture became important in all countries under Roman rule. In fact, the first four centuries of the Christian Era may justly be called the First Golden Age of Glass. The glassmakers of this time knew how to make a transparent glass, and they did offhand glass blowing, painting, and gilding (application of gold leaf). They knew how to build up layers of glass of different colors and then cut out designs in high relief. The celebrated Portland vase, which was probably made in Rome about the beginning of the Christian Era, is an excellent example of this art. This vase is considered one of the most valuable glass art objects in the world.

The Middle Ages.

Little is known about the glass industry between the decline of the Roman Empire and the 1200's. Glass manufacture had developed in Venice by the time of the Crusades (A.D. 1096-1270), and by the 1290's an elaborate guild system of glassworkers had been set up. Equipment was transferred to the Venetian island of Murano, and the Second Golden Age of Glass began. Venetian glass blowers created some of the most delicate and graceful glass the world has ever seen. They perfected Cristallo glass, a nearly colorless, transparent glass, which could be blown to extreme thinness in almost any shape. From Cristallo, they made intricate lacework patterns in goblets, jars, bowls, cups, and vases. In the 1100's and 1200's, the art of making stained-glass windows reached its height throughout Europe.

By the late 1400's and early 1500's, glassmaking had become important in Germany and other northern European countries. Manufacturers there chiefly produced containers and drinking vessels. Northern forms were heavier, sturdier, and less clear than Venice's Cristallo. During the late 1500's, many Venetians went to northern Europe, hoping to earn a better living. They established factories there and made glass in the Venetian fashion. A new type of glass that worked well for copper-wheel engraving was perfected in Bohemia (now part of the Czech Republic) and Germany in the mid-1600's, and a flourishing industry developed.

Glassmaking became important in England during the 1500's. By 1575, English glassmakers were producing Venetian-style glass. In 1674, an English glassmaker named George Ravenscroft patented a new type of glass in which he had changed the usual ingredients. This glass, called lead glass, contains a large amount of lead oxide. Lead glass, which is especially suitable for optical instruments, caused English glassmaking to prosper.

Early American glass.

The first factory in what is now the United States was a glass plant built at Jamestown, Virginia, in 1608. The venture failed within a year because of a famine that took the lives of many colonists. The Jamestown colonists tried glassmaking again in 1621, but an Indian attack in 1622 and the scarcity of workers ended this attempt in 1624. The industry was reestablished in America in 1739, when Caspar Wistar built a glassmaking plant in what is now Salem County, New Jersey. This plant operated until 1780.

Wistar is one of the great names of early American glass. The second great American glassmaker was Henry William Stiegel, also known by his nickname, "Baron" Stiegel. Stiegel made clear and colored glass, engraved and enameled glass, and the first lead glass produced in North America. A third important American glassmaker was John F. Amelung, who became best known for his elegant engraved glass.

Another important early American glass, Sandwich glass, was made by the Boston and Sandwich Glass Company, founded by Deming Jarves in 1825. It was long believed to be the first company in America to produce pressed glass. But the first was actually the Bakewell, Page, and Bakewell Company of Pittsburgh, Pennsylvania, which began to make pressed glass earlier in 1825. These two companies and many others soon made large quantities of inexpensive glass, both pressed and blown. Every effort was made to produce a “poor man's cut glass.” In lacy Sandwich, for example, glassmakers decorated molds with elaborate designs to give the objects a complex, lacelike effect.

In the early 1800's, the type of glass in greatest demand was window glass. At that time, window glass was called crown glass. Glassmakers made it by blowing a bubble of glass, then spinning it until it was flat. This process left a sheet of glass with a bump called a crown in the center. By 1825, the cylinder process had replaced the crown method. In this process, molten glass was blown into the shape of a cylinder. After the cylinder cooled, it was sliced down one side. When reheated, it opened up to form a large sheet of thin, clear window glass. In the 1850's, plate glass was developed for mirrors and other products requiring a high quality of flat glass. This glass was made by casting a large quantity of molten glass onto a round or square plate. After the glass was cooled, it was polished on both sides.

Bottles and flasks were first used chiefly for whiskey, but the patent-medicine industry soon used large numbers of bottles. The screw-top Mason jar for home canning appeared in 1858. By 1880, commercial food packers began to use glass containers. Glass tableware was used in steadily increasing quantities. The discovery of petroleum and the appearance of the kerosene lamp in the early 1860's led to a demand for millions of glass lamp chimneys. All these developments helped to expand the market for glass.

Modern glassmaking.

Changes in the fuel used by the glass industry affected the location of glass factories. In the early days when wood was used as fuel, glassworks were built near forests. By 1880, coal had become the most widely used fuel for glassmaking, and glassmaking operations were near large coal deposits. After 1880, natural gas became accepted as the perfect fuel for melting glass. Today, most glass manufacturing plants are near the major sales markets. Pipelines carry petroleum and natural gas to the glass plants.

After 1890, the development, manufacture, and use of glass increased rapidly. The science and engineering of glass as a material are now so much better understood that glass can be tailored to meet an exact need. Any one of thousands of compositions may be used. Machinery has been developed for precise, continuous manufacture of sheet glass, tubing, containers, bulbs, and a host of other products.

New methods of cutting, welding, sealing, and tempering, as well as better glass at lower cost, have led to new uses of glass. Glass is now used to make pipelines, cookware, building blocks, and heat insulation.

Ordinary glass turns brown when exposed to nuclear radiation, so glass companies developed a special nonbrowning glass for use in observation windows in nuclear power plants. More than 10 tons (9 metric tons) of this glass are used in windows in one nuclear power plant. In 1953, automobile manufacturers introduced fiberglass-plastic bodies. Today, such materials are used in architectural panels to sheathe the walls of buildings. They are also used to make boat hulls and such products as missile radomes (housings for radar antennas). Other types of glass have been developed that turn dark when exposed to light and clear up when the light source is removed. These photochromic glasses are used in eyeglasses that change from clear glasses to sunglasses when worn in sunlight.

During the late 1960's, glass manufacturers established collection centers where people could return empty bottles, jars, and other types of glass containers. The used containers are recycled—that is, broken up and then melted with silica sand, limestone, and soda ash to make glass for new containers. Glass can be recycled easily because it does not deteriorate with use or age. In addition to the collection centers, some communities have set up systems to sort glass and other reusable materials from regular waste pickups.

In the 1970's, optical fibers were developed for use as "light pipes" in laser communication systems. These pipes maintain the brightness and intensity of light being transmitted over long distances. Types of glass that can store radioactive wastes safely for thousands of years were also developed during the 1970's.

The late 1900's brought important new specialty glasses. Among the new specialty glasses were transparent glass ceramics, which are used to make cookware, and chalcogenide glass, an infrared-transmitting glass that can be used to make lenses for night vision goggles.

 


Steve W. Martin, Ph.D., Professor of Materials Science and Engineering, Iowa State University.

"Glass," Discovery Channel School, original content provided by World Book Online

 

 

What is Quartz?
From Wikipedia, the free encyclopedia

Quartz belongs to the rhombohedral crystal system. The ideal crystal shape is a six-sided prism terminating with six-sided pyramids at each end. In nature quartz crystals are often twinned, distorted, or so intergrown with adjacent crystals of quartz or other minerals as to only show part of this shape, or to lack obvious crystal faces altogether and appear massive. Well-formed crystals typically form in a 'bed' that has unconstrained growth into a void, but because the crystals must be attached at the other end to a matrix, only one termination pyramid is present. A quartz geode is such a situation where the void is approximately spherical in shape, lined with a bed of crystals pointing inward.

Varieties

Quartz goes by an array of different names. The most important distinction between types of quartz is that of macrocrystalline (individual crystals visible to the unaided eye) and the microcrystalline or cryptocrystalline varieties (aggregates of crystals visible only under high magnification). Chalcedony is a generic term for cryptocrystalline quartz. The cryptocrystalline varieties are either translucent or mostly opaque, while the transparent varieties tend to be macrocrystalline.

Although many of the varietal names historically arose from the colour of the mineral, current scientific naming schemes refer primarily to the microstructure of the mineral. Colour is a secondary identifier for the cryptocrystalline minerals, although it is a primary identifier for the macrocrystalline varieties. This does not always hold true.

Not all varieties of quartz are naturally occurring. Prasiolite, an olive coloured material, is produced by heat treatment; natural prasiolite has also been observed in Lower Silesia in Poland. Although citrine occurs naturally, the majority is the result of heat-treated amethyst. Carnelian is widely heat-treated to deepen its colour.

Because natural quartz is so often twinned, much quartz used in industry is synthesized. Large, flawless and untwinned crystals are produced in an autoclave via the hydrothermal process: emeralds are also synthesized in this fashion.

Quartz occurs in hydrothermal veins and pegmatites. Well-formed crystals may reach several metres in length and weigh hundreds of kilograms. These veins may bear precious metals such as gold or silver, and form the quartz ores sought in mining. Erosion of pegmatites may reveal expansive pockets of crystals, known as "cathedrals."

Quartz is a common constituent of granite, sandstone, limestone, and many other igneous, sedimentary, and metamorphic rocks.

Quartz is the most common material identified as the mystical substance maban in Australian Aboriginal mythology. It is found regularly in passage tomb cemeteries in Europe in a burial context, eg. Newgrange or Carrowmore in Ireland. The Irish word for quartz is grian cloch, which means 'stone of the sun'.

Roman naturalist Pliny the Elder believed quartz to be permanently frozen ice. He supported this idea by saying that quartz is found near glaciers in the Alps and that large quartz crystals were fashioned into spheres to cool the hands. He also knew of the ability of quartz to split light into a spectrum.

Nicolas Steno's study of quartz paved the way for modern crystallography. He discovered that no matter how distorted a quartz crystal, the long prism faces always made a perfect 60 degree angle.

Charles Sawyer invented the commercial quartz crystal manufacturing process in Cleveland, OH. This initiated the transition from mined and cut quartz for electrical appliances to manufactured quartz.

The quartz oscillator or resonator was first developed by Walter Guyton Cady in 1921 [1]. George Washington Pierce designed and patented quartz crystal oscillators in 1923 [2]. Warren Marrison created the first quartz oscillator clock based on the work of Cady and Pierce in 1927 [3].

Quartz crystals are rotary polar (see rotary polarization) and have the ability to rotate the plane of polarization of light passing through them. They are also highly piezoelectric, becoming polarized with a negative charge on one end and a positive charge on the other when subjected to pressure. They will vibrate if an alternating electric current is applied to them. This proves them to be highly important in commerce for making pressure gauges, oscillators, resonators and watches.

What is Fused quartz?
From Wikipedia, the free encyclopedia

Fused quartz and fused silica are types of glass containing primarily silica in amorphous (non-crystalline) form. They are manufactured using several different processes.

Fused quartz is made by melting high-purity naturally occurring quartz crystal at around 2000°C using either an electrically heated furnace (electrically fused) or a gas/oxygen-fuelled furnace (flame fused). Fused quartz is normally transparent.

Fused quartz can also form naturally. The naturally occurring form of fused quartz is usually referrred to as Metaquartzite and is formed under metamorphic conditions. Due to increased heat the crystals within the quartz become fused together.

Fused silica is produced using high purity silica sand as the feedstock, and is normally melted using an electric furnace, resulting in a material that is translucent or opaque. (This opacity is caused by very small air bubbles trapped within the material.)

Synthetic fused silica is made from a silicon-rich chemical precursor usually using a continuous flame hydrolysis process which involves chemical gasification of silicon, oxidation of this gas to silicon dioxide, and thermal fusion of the resulting dust (although there are alternative processes). This results in a transparent glass with an ultra-high purity and improved optical transmission in the deep ultraviolet. One common method involves adding silicon tetrachloride to a hydrogen-oxygen flame.

Fumed silica is manufactured by a similar flame hydrolysis process to synthetic fused silica, however it is in the form of a fine powder/dust and is typically used in applications such as fillers for rubbers and plastics, coatings, adhesives, cements, sealants, cosmetics, pharmaceuticals, inks and abrasives.

The optical and thermal properties are superior to those of other types of glass due to its purity (or rather, its lack of impurities). For these reasons, it finds use in situations such as semiconductor fabrication and laboratory equipment. It has better ultraviolet transmission than most other glasses, and so is used to make lenses and other optics for the ultraviolet spectrum. Its low coefficient of thermal expansion also makes it a useful material for precision mirror substrates.

 

 

 

Heat Induced Stress in Glass

 

Scientific Glassblowers fabricate simple to complex glass apparatus to be used under laboratory conditions - which can mean harsh chemical exposure, high and/or low pressures, and a host of other environments hostile to people and facilities. An awareness of product design is essential as well as the integrity of the glass structure itself. An element in product safety is the fabrication of stress or strain-free glass apparatus and systems. This is a very basic introduction to glass stress and annealing. Blowing glass in the fabrication of scientific glassware involves the use of a torch or burner. The flame is adjusted to varying degrees of sharpness, ranging from a pinpoint for precision work, to a large bushy flame used for heating and forming broad areas. This process of heating, forming and cooling will introduce stress (often referred to as strain) into the glassware. Invisible to the naked eye, the strain never- the-less is present and is a potential point of failure in the glass apparatus unless relieved. The amount of strain present will be determined by a number of factors including the intensity and size of the torch flame, glass wall thickness and the complexity of the seal itself. The severity of the stresses may be enough to cause glass failure.....sometimes while the glass piece is under construction! Many glassblower's hand anneal the work during the fabrication process, with full furnace annealing prior to customer receipt.
At no time should un-annealed glass apparatus be put into laboratory service, especially if it is to be subjected to heat, pressure or vacuum. An instrument used by glassblowers as an aid in detecting the presence of glass stress is known as a polariscope. Briefly, the use of two polarized filters held in varying orientation produces a very visible stress pattern when viewed through the instrument. An excellent and detailed explanation of glass stress, strain and polarisers is found in:

Manual of Scientific Glassblowing
I.S.B.N. 0 9518216 0 1
Chapter 11 - Stress and Strain in Glass Published by
British Society of Scientific Glassblowers

 

Another hidden type of stress.....yet can be just as damaging

Many people don't realize the stress put on their vacuum systems from improper assembly and clamping of glassware. It is VERY important that manifolds and all attached pieces are hung as straight as possible and that clamps are tightened evenly for both sides. If this is not done properly the glass is being "torqued" and can fail at any time. Since this strain is not visable except under polarized lights, it is not realized until you come in one day and find it broken or have it fail at a crucial time. If you find this to be a problem in your lab let me know and I will show the correct way of clamping. I can also "heat relieve" your system if your clamping method doesn't allow proper adjustment.

Contact me if you'd like to understand more about the dangers of heat induced (or physically induced) stresses in your glassware and what you can do to eliminate them.

Doug

 
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