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Bob Crager
Bob Crager of Lewis Street Glass is a 26 year veteran in the glass business. Lewis Street Glass is a leading Wichita Glass company, serving the entire Wichita/Sedgwick County area since 1919. They do anything and everything having to do with glass, both residential and commercial. They also do Auto glass. They are located at 743 South Market, facing Kellogg on the South, and you can reach them by phone at (316) 263-8259. You can email Bob Crager at bcrager@lewisstreetglass.com
Glass
2008-02-01 11:16:00
Which musical note can I learn to sing to break a glass?
Answer: There is a special human relationship with glass of every description that has enjoyed an unbroken history for thousands of years. Ever since our earliest ancestors figured out ways to manipulate different objects in their world, enabling them to work better and have better lives, human progress has depended upon our relationships with tools, and the various materials that make them. Glass happens to be one of the most versatile and useful materials to have been first, forged by nature, and then improved by human ingenuity. We’ve used glass to hunt, cook, construct buildings, protect us from some of the elements of nature, and beautify our bodies and homes. From eyeglasses to microscopes, to telescopes and windows, glass has given us a brighter and better perspective on the world around us. Along the way, a few myths have evolved. For example, many people believe that a glass window pane will very gradually grow thicker at the bottom as the glass window pane flows downward. And thanks to cartoons and comedy routines, other folks think that a certain pitch of the human voice can break glasses. Neither of these is true. Glass is a complete solid that will flow only when liquefied at temperatures of hundreds of degrees centigrade. An opera singer can warble all over the musical scale if she likes, but it will take the sound of a pretty large explosion to shatter glass. So, it’s time to shatter a few myths about glass, with a brief history of this wonderful substance, which is an essential, and mostly taken for granted part, of all of our daily lives. The first glass erupted on the scene millions of years ago…literally. The very first glass known to prehistoric peoples, which was used to craft utensils, weapons and decorative objects, was obsidian, or black glass. Obsidian was formed naturally from volcanic lava which cooled too quickly to revert to stone. It comprised the same core elements found in glass today, which were and are silica (quartz sand), soda and lime. Archaeologists and anthropologists have found ancient obsidian artifacts all around the world. Our ancestors discovered deposits of shattered obsidian which they crafted into a range of usable items. In the Western hemisphere this included Apache arrowheads for battle and hunting, as well as for implements that were used by the Aztecs in their human sacrifices. Cuneiform tablets were clay tablets, cones, and brick fragments inscribed using the ancient writing system known as cuneiform. The Sumerians invented this writing system, which involves the use of a wedge-shaped reed stylus to make impressions in clay. These tablets contained glass-making recipes indicating that glass was probably first manufactured by the people living in Syria, Babylonia (Iraq) and Mesopotamia (Iran), sometime around 3,000 BC. They also likely discovered the process by accident. In its earliest form, glass was made from impure ingredients, which resulted in a green tint. It was primarily decorative. A few thousand years would pass before glass possessed the clarity and transparency for making window panes. However, as time progressed, several compounds were introduced to create a range of colors for the purpose of mimicking precious and semi-precious stones. Some of these colorants were cobalt, copper, silver, chrome, iron, gold, manganese, nickel, selenium and cadmium. Glass was core formed or rod formed. Core formed objects were made by molding molten glass around a removable core or center, usually a combination of dung and clay mixed with water. In the rod forming technique, beads and other small items were made by manipulating a glob of molten glass on a long rod which was thrust into a kiln until the glass was malleable. In the third millennium BC, Phoenician trading vessels carried glass and glass-making to Egypt where it was used as decoration by the aristocracy, and as far away as the Celtic cultures of Britain. The Egyptians used glass beads as trading collateral in their dealings with other African peoples, who didn’t have access to the secrets of glass-making. The Romans, and other Europeans after them, continued using glass beads and other objects to trade in exchange for African valuables. Now, in jolly old England, early environmentalists were crying out that deforestation was becoming a problem as early as the 15th century. After 1615, glass-makers were required to use coal instead of wood in their furnaces. Then, in the late 17th century, the English discovered that adding lead oxide to the glass making process resulted in a substance which was solid, heavy and durable. Also, right about this time, the French perfected grinding and polishing techniques and produced the first plate glass, but only the very rich nobles could afford it. Then, in the 18th century, there was a political revolution in France and the start of an industrial revolution in England, and a revolution in glass production. Compressed air technology created flatter and better glass panes. Cooling air was blown into a large glass cylinder in controlled amounts. This cylinder was then split lengthwise. It was re-heated, and then allowed to flatten under its own weight. Large, relatively inexpensive panes of glass became available, and by 1860 flat glass prices had dropped, making glass affordable in all building construction. Transportation, communication and architecture have all benefited from more modern breakthroughs in glass production throughout the 20th century. Machines were developed that produced endless sheets of flat glass for window glass. New processes strengthened glass by thermal and chemical tempering. Tints were applied to glass to reduce heat transmission and glare, and glass coated with metal oxide films reflected heat or conducted electricity. But it is probably the motorcar that motivated the most important changes of all. Before 1919, windshields were made of ordinary plate glass, and were therefore highly dangerous when broken. The auto magnate, Henry Ford, created the new process of glass lamination, and laminated windshields became mandatory. The cellulose in the originals has since been replaced with polyvinyl butyral, known as PVB. Polyvinyl butyral resins are employed in a wide array of industrial and commercial applications. These unique resins have offered impressive performances, as well as outstanding versatility in such products as the manufacture of auto glass. Now, in the 1950s, side and rear windows were replaced by tempered glass, which breaks into small pebble-like pieces when broken, and normally do not cause injuries to passengers involved in a car crash. Fibre-optics and the first photo-sensitive glass came into being in the 1940s. In 1959, float glass replaced flat glass as a preferred material for residential and commercial windows. The most exciting recent development is Low-E glass, with a low-emission coating that improves the energy efficiency of windows. From early on to pretty recently, that’s part of the story of glass. A subject very near and dear to our hearts! Some research taken from the internet…More next month…
 
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