Glass is a material consisting mainly of silica, but it is also mixed with sodium carbonate and limestone and is produced at temperatures above 1,700 °C. The resulting product is hard, brittle and normally transparent. A unique characteristic of glass is that in its final form it retains a number of properties of both liquid and solid substances. This is called an amorphous material.
Specific properties of glass
Sometimes other materials are added during the production process to create specific properties. The addition of boric oxide provides oven-resistant glass, lead oxide creates a fine crystal glass, lamination of glass and plastic layers creates bullet-proof compositions, and toughened glass for car windows, for example, is made by cooling the glass very quickly during production. Waterjet cutting can be used for glass without the risk of crushing or tearing.