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 Tempered glass was made from ordinary glass heated to a temperature of about 650 degrees and then forced to cool rapidly, which produce a compression stress layer on surface and a tensile stress layer inside glass.
Tempered glass has approximately three times as strength as float glass of same thickness does. As the balance between surface compression stress layer and tensile stress layer inside collapses, the whole glass will instantly become small fragments. When ordinary glass breaks the glass fractures into large, sharp shards, which makes the possibility of the injury rises, in the meantime when tempered glass breaks the glass fractures into small fragments which makes tempered glass a high safety glass. Compared with ordinary glass, tempered glass also has a high heatproof effect towards sudden changes of temperature.
Accordingly, in the <<Safety Design Indicator of Using Glass in Open Part >> (The Japan Building Disaster Prevention Association), tempered glass has been recommended to use in parts where safety design is highly necessary.
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Glass is heated to about 650 degrees, then sent out of the furnace and shot by compressed air to cool down thoroughly.
On glass's surface, there forms a compression stress layer, whose thickness is up to 1/6 of that of glass, and inside the glass a tensile stress layer is formed. Under impact or weight, compared with float glass of same thickness, though tempered glass has approximately three times of strength, as one part fractures, the balance of stress collapses, the whole glass will fractures instantly. Moreover, flaw on surface or foreign materials rarely remain inside glass will cause flaw to grow, and when flaw reaches the inside tensile stress layer, even without any outside forces glass will suddenly fracture. However, even glass fractures, fragments will be small, so that the danger which influences the human body will decrease.
*NOTE
Since stress balance is maintained as a whole, and more, glass after tempering can not be cut off, so please order at correct size. Again, for same reason, glass after tempering treatment can not be drilled or notched.
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