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Home , Crown glass (optics), Fiberglass, Lead glass

REFLECTIONS An ancient yet modern marvel, the transparent material always remains at the surface of things

BY ALAN H. FEILER

10 BOSS 4 fa ll/w i nte r 2013 REFLECTIONS ON

LOOK AROUND. Glass is everywhere international —are the United Today, the countries in our lives, and its utilitarian and States, , , , India that are the world’s creative purposes are endless: It and . Not surprisingly, North preserves our food and beverages, Americans, Europeans and the Chinese leading exporters of provides our drinking vessels (which are the greatest consumers of glass, glass—which annually aptly enough are called ) and accounting for three-quarters of the dishes and cookware, helps improve our global demand. is a $75 billion vision (also called glasses), protects our Among the world’s leading glass international industry buildings and vehicles from external manufacturers are China’s Jiangsu intrusions and threats, preserves our Farun Group, France’s Compagnie de —are the United photographs and artistic treasures, and Saint-Gobain, Asahi Glass of Japan, States, France, greatly assists our scientifi c endeavors Pilkington of Great Britain and (test tubes, , telescopes, Guardian Industries of the U.S. Other Belgium, Japan, etc.). And glass optical fi bers enable us major glass companies are Schott AG in India and Germany. to take endless reams of data from Germany and Corning, Owens-Illinois across the globe and transmit them at and PPG Industries in the U.S.—which the speed of light, via the Internet. are among 1,500 American glass outfi ts In addition, glass allows us to with an estimated combined annual actually see ourselves. Aft er all, what revenue of approximately $25 billion. would our lives be like without Not too shabby for an ancient yet ? And cameras? Try video- modern material that people generally chatting without glass. tend to think of as greatly fragile, highly Plus, there are centuries of fi ne vulnerable and rather disposable. Glass artisans and craft smen who have taken has been compared to human nature. diff erent forms of glass and created “People are like ,” spellbinding and exquisite treasures suggested the late Swiss-American that illuminate the imagination, inspire psychiatrist and author Elisabeth and fi ll the human spirit and transcend Kübler-Ross. “Th ey sparkle and shine the centuries. when the sun is out, but when the Today, the countries that are darkness sets in, their true beauty is the world’s leading exporters of revealed only if there is a light glass—which annually is a $75 billion from within.”

www.dixonva lve.co m fa ll/w i nte r 2013 4 BOSS 11 52.1.93, Collection of The Corning Museum of Glass, 52.1.93, Collection of gift of Arthur A. Houghton, Jr. York, Corning, New

Left: The Morgan Cup. Roman Empire, first half of the first century AD Opaque white over translucent deep blue glass; blown and cased; carved, ground and polished. Right: A hand-colored engraving, which appeared in The Universal Magazine (London, 1760), depicts the manufacture of by blowing (left) and by casting (right). Glass workers were susceptible to cataract caused by the of the furnace.

Glass REFLECTING ON GLASS’S ORIGINS the sand into tubes called evolved in Venice Glass exists in nature, most often in fulgurites. These forms of glass were the form of obsidian, which is created used for jewelry, knives, arrowheads during the time of during volcanic eruptions, notes David and even currency. the Crusades (middle Whitehouse, a senior scholar at the Glass manufacturing is believed Corning Museum of Glass in Corning, to have begun in South Asia around to late Middle Ages), N.Y. “People, however, have been 1730 BCE. During the Roman Empire, and in the late 13th making glass for more than 4,000 years,” glassmaking had many domestic and he adds. industrial uses, as evidenced by the century an elaborate Historians believe that obsidian objects that have been discovered in guild system was was used by societies around the areas governed by the Romans. In fact, world during the Stone Age for the the word glass was first coined in the established there manufacturing of cutting tools. latter part of the Roman Empire era, for glassworkers. Archaeological evidence shows that with the term glesum originating most glass was first made in likely in the Roman glassmaking center (today’s Iraq and coastal northern Syria) in Trier (now in Germany). The Latin as during the third century BCE. word stems from the Germanic term for , Syria and other Mediterranean a lustrous, transparent substance. countries were glassmaking centers in The Romans were the first to use the centuries before Christ, and priests glass for windows, circa 100 AD in and ruling classes considered glass Alexandria. They tended to use glass to be as valuable and prestigious pebbles laid out on a wooden frame. as jewelry. Clear glass panes were first invented in Besides obsidian, early the late third century. Subsequently, artisans found that mullioned glass was used for windows natural glass was among Europe’s elite and well-to-do, as formed when well as for cathedrals. (It wasn’t until the lightning struck 17th century, however, that glass was sand and the commonly used for windows for heat would ordinary houses throughout Europe.) sporadically During the first centuries of the Common Era, the art and production of Obsidian glassmaking flourished. Glassmakers

12 BOSS 4 fa ll/w i nte r 2013 devised the process of offhand glass blowing, painting and gilding, and showed how to create layers of colors on DID YOU KNOW ... ? glass and cut out designs in high relief. Glass manufacturing evolved in The blowpipe was invented around 30 BCE, probably along the Venice during the time of the Crusades • (middle to late Middle Ages), and in the Mediterranean coast. This invention was revolutionary in the history late 13th century an elaborate guild of glassmaking. The craft of glassblowing was passed down from system was established there for father to son, and from master to apprentice. glassworkers. Venetian glassblowers • The formulas and procedures used in glassmaking were a closely created some of the most exquisite guarded secret throughout history. At times, the penalty for glass ever made, according to art disclosing techniques was death. historians, including glass, a transparent, virtually colorless glass • When breaking, glass cracks at speeds of up to 3,000 miles per hour. that can be created in any shape and • The Corning Museum of Glass, in Corning, N.Y., with more than to extreme thinness. 45,000 pieces, possesses the world’s largest collection of . Glassmaking became an important trade in Germany and • A modern glass bottle would take 4 millennia or more to decompose. during the late 1400s and 1500s. In • Glass has the quickest turnaround of any recycled curbside product. 1674, English glassmaker George It can be back on store shelves in as little as 30 days. Ravenscroft—who had familial ties to Venice’s glass artisan community— • The four sectors of the glass industry—container, flat, specialty and patented a new type of glass called —produce more than 20 million tons of glass annually, glass. In quantities of 10 to 30 percent, used for myriad consumer products. lead oxide was added to improve the The auto industry uses an estimated 500 million square feet appearance of glass and make it • easier to melt in furnaces fueled of glass annually. Also, 15 to 20 percent of a ’s surface today by coal. This process made glass consists of glass. easier to manipulate and decorate, • The world’s tallest glass building is The Shard in London, which and the production of opened in July 2012. Also known as the Shard of Glass or Shard galvanized the British economy and London Bridge, the 95-story skyscraper stands 1,020 feet high allowed England to overtake Venice and features 11,000 panes of glass. as the glass industry’s capital in the 18th and 19th centuries. Lead glass proved to be invaluable to the optical community, particularly for the manufacturing of optical , telescopes and microscopes. American glassmaking originated in 1608 in the settlement of Jamestown in the colony of Virginia, and by the early 1800s, glass—also known as crown glass—was the primary glass in demand in the . Glassmakers blew a bubble of glass and spun it until it was flat to create crown glass. By the 1850s, plate glass was developed for mirrors and other products. This glass was made by casting molten glass onto a round or square plate, cooling it and polishing both sides. Clockwise from left: Mullioned window of the medieval Priori Palace; The Shard, London, the world’s tallest glass building; a goblet from London’s York of Glass, Corning, New Savoy glasshouse of , 1676-1678. Colorless glass; blown, pattern-molded, applied. 50.2.2 Collection of The Corning Museum 50.2.2 Collection of www.dixonva lve.co m fa ll/w i nte r 2013 4 BOSS 13 The Secret Behind Bullet- Proof Glass

What gives bullet-resistant glass the ability to stop bullets? While processes vary by manufacturer, the basic strategy involves layering a polycarbonate material between pieces of ordinary glass in a process called . Polycarbonate is a tough transparent — SCHOTT AG SCHOTT usually between 7 and 75 millimeters in thickness. Left: Cullet. Above: A melting tank A bullet fi red at a sheet of bullet-resistant glass will In the 1890s, the MAKING GLASS pierce the outside layer of manufacturing of glass Generally speaking, glassmaking has changed and increased the glass, but the layered remained the same since ancient times. exponentially. With the advent of polycarbonate-glass material is able Most glass contains three primary machinery (and eventually pipelines to absorb the bullet’s energy and ingredients: silica (which is usually that carry petroleum and natural gas to stop it before it exits the fi nal layer. found in sand), soda or (which plants), the making of glass—for bulbs, lowers the temperature aft er sand melts) tubing, sheet glass and many other and lime (which provides stability to uses—allowed for more precision and a generally unstable combination). mass productivity. In 1904, the fi rst Aft er being stored in silos, prepared automatic bottle-making machine was and mixed, the raw materials (called the invented by Michael J. Owens in Toledo, batch) for glass are transported to a Ohio, and by the mid-1920s a fully furnace. Cullet (recycled glass or waste automatic machine to blow electric glass) is added to the batch to accelerate light bulbs was developed by Corning reactions. Melting the raw materials Glass Works in New York. Elias Snitzer requires temperatures of 2600 to 2900 of the American Optical Corp. invented Fahrenheit (1427 to 1593 C), depending laser glass in 1961. Two decades later, on the composition of the materials. Corning Glass Works introduced Particularly large quantities of glass are transparent glass cookware. made in furnaces known as day tanks. Today, glass can be recycled to Most glass, however, is made in large make glass for new containers, furnaces known as continuous tanks, particularly when mixed with silica where 400 to 600 tons of fl at glass can sand, and soda ash. Th e be melted per day for production. recycling of glass is relatively easy In the case of soda-lime glass— because glass does not age or which is largely composed of silica diminish with constant usage. and sodium oxide from soda ash, as Furthermore, since the 1970s, well as lime and other additives, and glass has been utilized to store is used for drinking bottles and windows radioactive wastes. And glass has been —mass production is conducted in used for the creation of specialty glasses, gas-fi red units. For specialty glasses, such as an infrared transmitting glass smaller scale furnaces are used, that can be used for lenses in night including electric melters, pot furnaces vision goggles. and day tanks.

14 BOSS 4 fa ll/w i nte r 2013 SCHOTT AG SCHOTT

Schott Glass manufactures the world’s first , Borofloat, using a microfloat process.

of glass into a mold and then pressing it from tension caused by uneven cooling. with a plunger until it fills the mold. In involves reheating glass and the drawing process, molten glass is cooling it according to a planned drawn in an upward into a sheet timetable and temperature schedule. through rollers, with the thickness of After this long process, glass the sheet determined by the speed of plant engineers inspect the glass by the draw itself and by the configuration testing samples for quality and desired Glass blowing furnace of the draw bar. Casting occurs when properties. With blown glass items, molten glass is poured into molds with excess glass is often removed by scoring After the melting process, the ladles—or straight from the furnace. the pieces with a diamond or glass is formed after undergoing homogenization and the removal of Generally speaking, glassmaking has remained the same bubbles. In the case of flat glass for windows and other uses, a floating glass since ancient times. Most glass contains three primary process is employed in which the top ingredients: silica, soda or potash, and lime. surface of the glass is subjected to nitrogen under pressure to obtain a polished finish. Glass for bottles and Once the form for glass is achieved, wheel, and snapping them off with jars is produced by blowing and it is annealed (heated and then slowly sudden pressure. If glass edges are pressing processes. cooled) to remove strains and stresses. too rough, they are usually polished Four methods exist for the shaping This process might also include surface with abrasives or flames from a of glass: blowing, pressing, drawing and treatments, and coatings and/or fire-polishing instrument. casting. Blowing is conducted through lamination to enhance the chemical After the finishing process, glass the ancient practices of a blowpipe. durability, strength or optical proper- is decorated in various . The Pressing is done by dropping a hot glob ties. If not annealed, glass may shatter etching process requires that glass be

From left to right: A vase is shaped through glass blowing; raw material that has been melted in the pot at Schott in Mainz, Germany, is rolled to flat glass. SCHOTT AG SCHOTT

www.dixonva lve.co m fa ll/w i nte r 2013 4 BOSS 15 FACTS & FIGURES/

Optical

WORLD GLASS INDUSTRY STATS

• ANNUAL INTERNATIONAL GLASS INDUSTRY REVENUE: Japan, Pilkington of Great Britain, Germany’s Schott AG $75 billion and Guardian Industries, Corning, Owens-Illinois, and PPG Industries of the U.S. • LEADING GLASS EXPORTERS: U.S., France, Belgium, Japan, India and Germany • PRODUCTS IN GREATEST DEMAND: Containers, bottling, automotive and construction industrial needs • LEADING SPECIALTY PRODUCTS: Lenses, optic fibers, mirrors, glassware, TV tubes (all of which account for 60 percent • VALUE OF GLASS PACKAGING MARKET: $35 billion of global glass revenue) • BIGGEST CONSUMERS: North America, China and Europe • LEADING GLASS COMPANIES: China’s Jiangsu Farun Group, account for 75 percent of global demand for glass. France’s Compagnie de Saint-Gobain, Asahi Glass of

16 BOSS 4 fa ll/w i nte r 2013 dipped in or sprayed with hydrofl uoric “Th e speed of change today Improved melting and refi ning acid and some of its compounds etched. makes forecasting a risky business,” processes will be necessary to alleviate Th e surface may be frosted, rough or he writes. “It is almost certain that environmental concerns while opaque, or it could have a translucent, new generations of glass and products increasing product yield, lowering smooth quality. Sandblasting can also that incorporate glass will appear. energy demands and reducing be used to give glass a translucent As scientists make increasing use of production costs. All these issues will design; the process involves blowing nanotechnology [the manipulation of help improve the competitiveness of compressed air and sand against the matter on a molecular scale] to improve glass products and create a leaner, glass while using a rubber stencil to existing types of glass and devise new cleaner processing system. And of create an image. ones, the pace of change is likely to course, the recycling of glass will be In addition, enamels and lusters become even faster.” key to that mission. can be applied to glass by hand painting Th e glass industry must continue More than 2 millennia ago, or the process of transferring decals, to devise superior products (translation: the Roman author, naturalist and or by silk-screening. When the decora- lighter and stronger) that will appeal to philosopher Pliny the Elder observed, tions are heated, they fuse to the glass the consumer base. will be “Neque est alia nunc sequacior materia and become part of the piece. Th is is needed to support the proliferation of aut ... accommodatior” (Today no other how many glass products—such as glass products in new markets and material is more pliable ... or adaptable jugs, pitchers and lighting devices— industries, especially with the advent than glass). are decorated. of the information age. Th ose words about the unique and In particular, glass industry eternal nature of glass are as true today A CLEAR VISION observers say, more research is needed as when they were penned during the What is the future of glass? In his for new glass processing technology Roman Empire. Like love and art, book Glass: A Short History, David to reduce greenhouse gas emissions, glass is here to stay and will remain Whitehouse makes it clear that waste and energy use while increasing a critical part of our lives. Just look in predictions aren’t easy to make. the productivity of glass furnaces. the .

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