Also known as tempered glass, TSG is a Grade A Safety Glass that is easily identifiable in its broken state. This is from its characteristic small dice sized particles of glass which significantly reduce the risk of severe injury and deep lacerations.
The toughening process involves heating of the glass to a very high temperature and then rapidly cooling by blasting air on the surface. This creates high compression stresses in the glass surface which are balanced by tensile stresses in the centre. The compressive stresses press any surface flaws closed preventing crack migration and glass failure.
The toughened glass surface is not as hard as annealed glass, and so manufacturers often apply coatings and/or laminates to the surface of the glass. Toughened glass must have all its finishing work (e.g. holes, chamfers and polishing) undertaken prior to the process of toughening being undertaken.