Materials (Glass)


(the following informative notes on materials are all from 'Materials for Builders & Architects' by Arthur Lyons)

Glass: Modern glass is made from sand (silica), soda ash and limestone, with some other small additional ‘things’. There is about 70% silica in glass.

Manufacture: Forming processes: There are several ways to produce glass objects. Early methods were manual and laborious. However, when the float glass method was developed, it revolutionized the glass industry. Glass floats on liquid tin and is cooled after having been heated to 1500C. This is a continuous process. Before this method, glass was made by manually blowing into tubes to which molten glass was attached. The size of this ‘crown glass’ was mainly determined by the strength to the person. In the 20th Century, new ways of producing glass were developed. For instance the Colburn and Fourcault processes which allowed the making of flat glass directly. However, this glass has many imperfections. Because of this the float process developed by Pilkington in 1959 became so successful.

Toughened Glass & Laminated Glass: Essentially these two types of glass make the glass harder to shatter by different methods of treatment. Laminated glass usually has thin layers of a plastic substance between two or more sheets of glass. It is very tough. The more layers, the stronger the laminated glass is. However, this might greatly reduce transparency. Toughened glass is very hard to shatter. When it does, it forms into small granules of glass which should not cause serious injury. This is often considered a safety glass. It is made by heating the glass and cooling rapidly so that the outer layer is harder than the core. Heat-strengthened glass works in a similar way, but it usually made with a slower cooling and is therefore weaker. Laminate glass can be made into bullet-resistant glazing, since it can be very resistant to impact when the interlayers are thick and numerous. This doesn’t mean it cannot be broken: the common belief of ‘bullet-proof glass’ does not exist – if a bullet is a high calibre and the impact speed is high enough, even the toughest glass will yield.

Other types of Glass: Many different things can be achieved with the usage of glass, from aesthetics, acoustic control, solar control, heat control, etc.