| Glass |
Explore glass chemical composition
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Almost all commercial glasses fall into one of three basic categories. These categories are based on chemical composition. There are numerous compositions, all distinct, even if fused silica is always present.
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 Glass is by definition an amorphous solid material made by fusing silica with a basic oxide. Glass is called amorphous because it is neither a solid nor a liquid but exists in a vitreous, or glassy, state. Architectural glass is made from three principal raw materials, easily found in nature: silica, lime and sodium carbonate. The secondary materials are used to give special properties to glass or to facilitate the glass-making process. By mixing secondary materials with the basic raw materials in the right percentage different types of glass are obtained, which can be categorized into three broad categories:
Soda-lime glass:
This is the most common commercial glass (90% of total production), and also the least expensive. The chemical and physical properties of soda-lime glass are the basis for its widespread use. Soda-lime glass is primarily used for bottles, jars, everyday drinking glasses, and window glass. It usually contains 60-75% silica, 12-18% soda, and 5-12% lime. Soda-lime glass is resistant neither to high temperatures nor sudden thermal changes, nor to corrosive chemicals.
Lead glass:
As the name already indicates, lead glass has a high percentage of lead oxide (at least 20% of the batch). Lead glass has a relatively soft surface, making it especially suited for decorating using grinding, cutting, and engraving processes. This glass will not withstand high temperatures or sudden changes in temperature.
Borosilicate glass:
The third major group, borosilicate glass, is any silicate glass having at least 5% of boric oxide in its composition. It demonstrates greater resistance to thermal changes and chemical corrosion. Thanks to its properties, borosilicate glass is suitable for use in industrial chemical process plants, in laboratories, for ampoules and vials in the pharmaceutical industry, in bulbs for high-powered lamps, etc. Borosilicate glass is also used in the home for cooking plates and other heat-resistant products.
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Photos: Bungi
Last review: December, 2004 |
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