Tempered Glass Windows - Safer Glass

Tempered glass (also known as toughened glass in some countries) has much improved safety and security benefits over annealed (ordinary) glass. So the number of homeowners installing tempered glass windows when replacing windows in their home is on the increase.

But it is important to understand that a tempered glass window is not an unbreakable window, the glass can still break. Fully tempered glass is still excellent for window safety though. As it will be somewhere around four times stronger than ordinary glass of the same type, size and thickness.

This extra strength means that tempered windowpanes can withstand greater impacts than ordinary glass can, as well as being more endurable against stress from thermal energy (heat).

The strength within tempered glass is achieved through surface and edge compression. This is brought about by tactical uses of heating and rapid cooling during the manufacturing process. Tempered glass is a `heat-treated glass' along with its relative, heat-strengthened glass. However heat-strengthened glass is not as strong as fully tempered glass, so don't let anyone tell you it is!

Compress To Resist Stress

The surface compression (which brings the strength) is measured in what is known as psi (pounds-square-inch). In order to comply with the relevant standards, the following rules apply.

Ordinary annealed glass has surface compression less than 3500 psi
Heat-strengthened glass must have surface compression between 3500 and 7500 psi
Fully tempered glass must have a surface compression of 10,000 psi as a minimum.

The design of windows made from tempered glass means that even if they do break: the glass will burst apart into many hundreds of small and blunt fragments which are sometimes known as `dice' because they are so shaped. This is obviously a whole lot safer than the large and dangerous shards associated with breakages of ordinary glass.

Tempered glass must be shipped and installed with due care though, for the glass can not crack as ordinary glass does and sometimes will not show signs of trouble immediately either. If dealt with very clumsily, any sudden temperature change or contact once installed can cause an overload and result in a spectacular and astonishing window eruption which is known as a `spontaneous breakage'.

Also see; window types.

Author Notes:

Anthony Lee contributes and publishes news editorial to http://www.replacement-windows-n-shutters.com. Find everything you need to know about replacement windows, shutters, tinting, basement, fiberglass windows and more.