robertson’s glazing                   PH. 8264 4161


Glass types

Float glass

The float glass process was invented by Pilkington and the first line in Australia was commissioned in 1972. 

Glass is manufactured by melting sand, soda ash, dolomite and limestone together and produces a continuous glass ribbon – 3660mm wide (after rebuild). This flows from the furnace and ‘floats’ the glass over a bed of molten tin. It is then carefully cooled to anneal the glass – a process which modifies the internal stresses enabling it to be cut and which maximises its potential mechanical resistance.

Decorated / Patterned glass

This involves embossing a pattern into the glass during manufacture by passing the semi molten glass through a set of rollers prior to annealing. One side remains smooth and a square wire mesh can also be included.

Insulating glass units

Also known as double glazed units where two or more panels of glass bonded to a perimeter spacer, either metal or thermoplastic spacer (TPS), with either air or argon gas filling used in the space between the glass panes. Their primary benefit is insulation and solar control. Most types of glass can be incorporated into an insulating glass unit.

Laminated safety glass

Comprises two or more layers of glass permanently bonded together with an interlayer or resin. If broken, the interlayer is designed to hold the glass together. Virtually all glass types can be laminated and the thickness and type of interlayer can be varied to provide ballistic, bomb or physical attack resistance. Normal laminated glass can be cut and further processed.

Toughened safety glass

Float or DecorPatterned glass is placed in a roller hearth toughening furnace. The glass is heated then rapidly cooled, resulting in the glass retaining high compressive stresses. Fully toughened glass is 4 to 5 times stronger than ordinary glass and if broken forms small granules.


High quality float glass is backed with silver and protective coats of baked enamel paint. It can also include a vinyl backing for safety.