Thermally Toughened Glass

Glass which has been heat-treated using a method of controlled heating and cooling which locks the surface of the glass in a state of compression
Virtually all glasses can be thermally toughened: clear and coloured Planibel, Stopsol, Sunergy, Imagin, etc.
Certain types of glasses with a magnetron coating are also toughenable; this requires some adjustments to the toughening procedures
Thermal toughening can be combined with silk-screen printing or enamelling
Use: single glazing, insulating glazing, laminated glazing and so on for applications where the following are required:
- Greater resistance to mechanical shocks (glass doors, glass units with punctual settings, etc.)
- Greater resistance to thermal stresses (glasses exposed to solar radiation with possible shadows which cause stresses in the glass, etc.)
- Greater protection against the glass breaking thereby reducing the risk of injury
Once toughened, the glasses cannot be sawn, cut, drilled or processed
Complies with standard EN 12150

Spontaneous breaking
Toughened glass can break spontaneously due to the presence of nickel sufide. To avoid this, a Heat Soak treatment can be requested.
Optical performance
The thermal toughening process causes the surface of the glass to distort in two ways:

- Overall bend of 3 mm/m*

- Localised bend of 0.5 mm/300 mm*

* Values for Planibel heat-strengthened glass using the horizontal process

This phenomenon may be more visible in coated glasses.
Anisotropy
Anisotropy is caused by compression of the surface of the thermally toughened glass. Under natural lighting conditions, the reflection characteristics vary from one point to another and differently coloured patterns known as "leopard spots" may be seen on the glass.

This particular aspect is inherent to thermally toughened glass.