Toughened glass is a strong glass that has low visibility. It is available in all thicknesses and when it is broken it forms small granular chunks that are dangerous.
There are two different types of heat-treated glasses, heat-strengthened and tempered. The differences between the two glasses are as follows:
- With tempered glass, the cooling process is accelerated to create higher surface compression (the dimension of force or energy per unit area) and/or edge compression in the glass. It is the air-quench temperature, volume and other variables that create a surface compression of at least 10,000 pounds per square inch (psi). This is the process that makes the glass four to five times stronger and safer than annealed or untreated glass. As a result, tempered glass is less likely to experience a thermal break.
- With heat-strengthened glass, the cooling process is slower, which means the compression strength is lower. In the end, heat-strengthened glass is approximately twice as strong as annealed, or untreated, glass.