Monday, June 4, 2012

How is Glass Made?

            Glass sheets have a wide application; they are used in windows of houses, trains, motorcars, ships and aero planes. The list of its products is, in fact, endless and includes water tumblers, decoration articles, and various kinds of bottles, sunglasses, spectacles, flasks, laboratory items, light bulbs, fluorescent tubes and a large number of other items used in our daily life. There is hardly any field in which glass is not used in some form or the other. Do you know how his useful material is made?

A Glass Making Plant

            The art of making glass is very old. A blue glass rod made in 2,600 B.C. was found in Babylonia. It is evident from these finding that man knew the art of making glass some time around 2,600 B.C.

            Sand silica, soda sodium carbonate and lime calcium carbonate are the main constituents used in the manufacture of glass. These materials are finely ground, mixed together and melted in a big furnace. When the mixture becomes homogeneous after melting, it is moulded in the form of sheets or rods. The solid material so formed is glass.

            There are many kinds of glass. To make different kinds of glass, some additives are mixed to the aforesaid mixture before melting it. In general, magnesium oxide, boric oxide, aluminum oxide, zinc oxide, lead oxide is the main additives used in glass manufacturing. For making colored glass, oxides of copper, iron, selenium, chromium, cobalt etc. are used. Cobalt salt is mixed to make blue glass, chromium or copper compounds impart green color, whereas selenium salts makes glass red.

            There is also fiberglass, which is being used in research work. Today, scientists have developed a kind of glass, which changes its color when illuminated. A special kind of glass is now in use for making bricks used in building houses. By mixing special materials to glass before melting. Transparent substance which is as strong as steel has been developed. This type of steel is used in space ships. Coating the surface of borosilicate glasses with a metallic oxide makes it a conductor of electricity. These kinds of glasses are used in panels for industrial and house heating.