Tempered Glass Demystified
The fundamental process of tempering was discovered in the 1600s and first patented in 1900. Today, tempered glass products can be found all around us, filling a variety of different specialty applications where strength and/or safety are specified.
A type of safety glass created with controlled chemical or thermal treatments to increase its strength when compared to annealed or “normal” glass.
Tempered glass is four to five times stronger than annealed glass which makes it desirable in transportation, architectural and a variety of other applications. In addition, its balanced internal stresses enable the glass, when broken, to crumble into small, harmless “chunks” instead of splintering into sharp, jagged shards.
Flat glass is heated to 600 degrees Celsius and then cooled rapidly, or “quenched,” with concentrated air currents, manipulating temperature and pressure (at times greater than 10,000 psi) to achieve the desired properties. The cooling differential created between the surface and central layers of the glass creates surface compression and internal stresses which underly the enhanced strength.