Tempered glass

Tempered glass is a type of glass that undergoes a heating cycle at a temperature of about 700°C, followed by rapid cooling, with streams of  cold air. As a result of the thermal shock, a state of "compression" is created on the surface of the glass, which results in an improvement in mechanical strength. If the hardened layer is scratched, the tempered glass can shatter into small, harmless fragments. For this reason, and due to its high mechanical resistance, tempered glass is called safety glass.