Tempered Glass
Glass that has been heat-treated to increase its strength approximately 4-5 times compared to annealed glass, and breaks into small granular pieces rather than sharp shards.
Tempered glass (also called toughened glass) is classified as safety glass under Canadian building codes. It is required in locations where human impact is likely: doors, sidelites, shower enclosures, glass railings, low windows, and areas near stairs.
The tempering process involves heating glass to approximately 620°C and then rapidly cooling it. Once tempered, glass cannot be cut or drilled — all fabrication must occur before tempering. Tempered glass can be identified by the permanent etch mark typically found in one corner.