The properties of glass are mainly governed by factors such as composition of the constituents, state of surface, thermal treatment conditions, dimensions of specimen, etc.
Following are the properties of glass which have made the glass popular and useful.
(1) It absorbs, refracts or transmits light.
(2) It can take up a high polish and may be used as substitute for every costly gems.
(3) It has no definite crystalline structure.
(4) It has no sharp melting point.
(5) It is affected by alkalies.
(6) It is an excellent electrical insulator at elevated temperatures due to the fact that glass can be considered as an ionic liquid. The ions are not easily moved at room temperature because of the high viscosity. But when the temperature rises the ions are permitted to flow and thus they will sustain an electric current.
(7) It is available in beautiful colours.
(8) It behaves more as a solid than most solids in the sense that it is elastic. But when the elastic limit is exceeded, it fractures instead of deforming.
(9) It is capable of being worked n many ways. It can be blown, drawn or pressed. But it is strange to note that it is difficult to cast in large pieces.
(10) It is extremely brittle.
(11) It is not usually affected by air or water.
(12) It is not easily attacked by ordinary chemical reagents.
(13) It is possible to intentionally alter some of its properties such as fusibility, hardness, refractive power, etc. to suit different purposes.
(14) It is possible to obtain glass with diversified properties. The glasses may be clear, colorless, diffused and stained.
(15) It is possible to weld pieces of glass by fusion.
(16) It is transparent and translucent. The transparency is the most used characteristic of glass and it is due to the absence of free electrons. For the same reason, it also works as a good
It can thus be easily appreciated that glass, though used for thousands of years, is just beginning to be understood and it is still possible to get a variety of glasses with certain chemical additives. Further investigations are yet in the process for preparing glass with extraordinary unusual characteristics and thus to increase the utility of this unique and complex material.
As a matter of fact, the glass industry has made enormous progress all over the world and the glass has become very cheap and useful to the poor as well as to the rich.