The toughening process involves a heating and cooling treatment that creates high compressive stresses on the surfaces of the glass, balanced by tensile stresses in the center. This process enhances the glass’s strength against impact and thermal stress loads while maintaining its original volume, chemical composition, color, and clarity.

Tempered glass is approximately five times stronger than annealed glass when it comes to impact resistance. It is suitable for use as safety glass because, upon breaking, it shatters into small, blunt-edged fragments that minimize the risk of injury.

Certain “tempering patterns” may only be visible under specific lighting conditions, and distortions within allowable bow and warp tolerances are generally accepted as inherent characteristics of the heat treatment process rather than defects.