Different Types of Glass

The most common division of glass is by chemical composition. In this way we see a division into the main groups.

Soda Lime Glass

finds its use in the foodstuffs industry as bottle and preserve glass as well as in the laboratory industry. The chemical composition of this glass consists of

71 - 75 % sand (SiO₂)
12 - 16 % soda and
10 - 15 % lime.

Soda lime glass is subject to acuate stress under heat shock and has a relatively high coefficient of expansion. It is particularly resistant to alkaline liquids.

Lead Glass

If in place of lime larger quantities of lead oxide are added, we obtain lead crystal glass. The chemical composition of this glass consists of

54 - 65 % sand (SiO₂)
18 - 38 % lead oxide
13 - 15 % soda and potash. 

Lead cystal is well known for its very high clarity, its ability to be cut and decorated and its 'ring' when tapped - all leading to its use for high quality domestic ware.

Borosilicate Glass

differs from soda lime and lead glass by using a higher proportion of sand (SiO^₂) The chemical composition of this glass contains

70 - 80 % silicon dioxide (SiO₂)
7- 13 % boron trioxide (B₂O₃) 
4 - 8 % Na₂O and K₂O
as well as 2 - 7 % aluminia oxide (Al₂O₃).

Glass with such composition is characterised by a high stabitlity against acidic attack, low thermal expansion and excellent temperature stability. This glass is particularly sutiable for laboratory and chemical use where contact with aggressive mateials is likely to be prolonged.