Tempered Glass

The tempering process produces highly desirable conditions of induced stress which result in additional strength, resistance to thermal stress and impact resistance.

Fully tempered glass must have a surface compression of 10,000 PSI (Annealed is below 3500 PSI) and heat strengthened must have a surface compression between 3,500 and 7,500 PSI.

The basic principle employed in the heat treating process is to create an initial condition of surface and edge compression. The condition is achieved by first heating the glass, then cooling the surfaces rapidly.

This leaves the center glass thickness relatively hot compared to the surfaces. As the center thickness then cools, it forces the surfaces and edges into compression.

Wind pressure, foreign object impact and thermal stresses or other applied loads must first overcome this compression before there is a possibility of breakage.

In the heat treatment process the key procedure is application of a rapid air quench immediately upon withdrawal of hot (1200 degrees F) glass from the tempering furnace. The immediate and sustained application of an air quench produces the temper.

A quenched condition becomes stable when the glass is reduced to a temperature of approximately 400-600 degrees F.

Tempered glass is about 4 times stronger than standard annealed.

When broken, Toughened Glass shatters into small blunt - edged fragments (dice) reducing the risk of human injury

Available in thicknesses ranging from 4-19mm (¼" - ¾")

Toughened glass sheet sizes up to 1.9 metres (75") by 3.8 metres (150"). Minimum size 280mm (11").