What is Glass & Qualities of Glass
Glass has been known to the old civilization of Egyptians 6000-5000 B.C. Venice has been a prosperous market for glassware and jewels for more than a century during the medieval times. During the last 100 years glass making has been given a scientific basis.
Any substance which has solidified from the liquid state without crystallization is known as glass. However, the term glass refers to the product that is obtained by the fusion of mixture of silica, basic oxides and a few other compounds. Thus the exact definition is glass may be defined physically as ” a rigid, super cooled inorganic liquid having no definite melting point and a sufficiently high viscosity (greater them 13 poise) to prevent crystallization. Chemically it is a mixture of alkali and alkaline earth silicates containing silicates and borates of other metals also having random structure”.
Requisite qualities of glass are: –
1) The material must liquefy at a conveniently feasible temperature.
On cooling the molten mass should not crystallize.
The molten glass should be such that it can be easily give the desired shape and form.
The glass should be resistant to the conditions for which it is manufactured.