Tempered Glass

Tempered glass is made by uniformly heating a piece of regular annealed glass to a temperature of up to 700° C and immediately cooling it.

The clean piece of glass enters the furnace where it is heated evenly for a predetermined amount of time based on the glass thickness and other factors. At the end of the heating cycle, this super-heated glass enters the cooling chamber.

In the cooling chamber, the glass undergoes a rapid cooling process called "quenching". This quenching process blasts the glass with high-pressure air via an array of nozzles. This cools the the outer surface of the glass much more quickly than the center. As a result, the center of the glass remains in tension, while the outer surfaces go into compression. It is this stress pattern that gives tempered glass its characteristic strength.

Characteristics of Tempered Glass

• Four to five times stronger than annealed glass of the same size and thickness.
• Higher thermal strength, and it can withstand high temperature changes up to 250° C.
• In the event of breakage, disintegrates into small, relatively harmless pieces.
• Tempered glass cannot be cut or altered.
• Optical distortions are a by-product of the tempering process.