Description
Glasses may be heat-treated to enhance their resistance to mechanical and thermal shocks.

There are three types of glass:
- heat-strengthened
- thermally toughened
- thermally toughened and Heat Soaked
Breakage pattern:
- into small blunt pieces (means that they may be considered safety glasses)
- of thermally toughened glass
- of thermally toughened glass and which may or may not be Heat Soaked
- into large sharp pieces of heat-strengthened glass (means that it cannot be considered safety glass)