Glass is used for various purposes in home, offices, factories, shops and almost every where. Today there is hardly any sphere of life in which glass is not employed in some form or other. The list of glass products is, in fact, endless and comprises water tumblers, tea- cups, plates, bottles, jars, bowels, flasks, test-tubes, different laboratory items, light bulbs, fluorescent tubes, television and computer picture tubes, decoration articles and a large number of other items used in our day to day life. Glass sheets are employed in manufacturing windows of houses, motor cars, trains, aeroplanes and ships. The sheets are also used as table top plate and in photo frames. Hence, glass is an important material. Do yuu know how this advantageous material is manufactured?
The art of making glass is very ancient. A blue glass rod made in 2600 BC was discovered from the ruins of Babylonia civilization of ancient period.
The main ingredients used in making of glass are sand (silca), soda (sodium carbonate) and lime (calcium carbonate). These materials are finely grinded, mixed together and melted in a big furnace. After melting, when the mixture becomes homogeneous, it is moulded in the shape of sheets, rods or of any other thing. Then it becomes the solid material of glass.
There are so many types of glass. To make different types of glass, some other materials are mixed with the mixture before melting it. Magnesium oxide and lead oxide are used as the chief additives in the glass manufacturing industry.
Different coloured glasses are manufactured. For making coloured glasses, oxides of copper, iron, selenium, chromium, cobalt etc are utilized. The cobalt salt is combined to make blue glass. Chromium or copper compounds bring green colour while selenium salts make red glass.