Toughened glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. ST Glass uses a thermal toughening process which compresses the outer surfaces of the glass while also placing the inner surfaces into tension.
This process strengthens the glass against surface impacts and pressure while also allowing the glass to crumble into small segments if broken. These small chunks tend to be almost blunt compared to the large jagged shards created from annealed glass, and the likelihood of injury is greatly reduced.
Glass that has been toughened using a thermal or chemical treatment can not be modified (cutting grinding or drilling) as it is the total compressive stress that the final full piece of glass has been placed under that gives it its unbelievable strength. By creating a hole in the glass or changing the edge, the glass will release the pressure rapidly from the newly modified area causing the glass to fracture.
After the process the toughened glass has a greater thermal resistance and has improved flexural and tensile strength, the colour, clarity and chemical composition of the glass remains unchanged. Glass that has been produced in this manner can also be laminated in order to make sure that after receiving an impact the individual shattered pieces stay in place using an anti splinter film that coats the outer surfaces.