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Safety Lenses 177

Glasses
Glasses may be:
1. Laminated glasses
2. Heat toughened glasses
3. Chemically toughened glasses
4. Special heat toughened safety glasses.

Laminated Glasses
Laminated glass lenses are made by the adhesion of two layers of crown
glasses to an inner layer of plastic material. These lenses are not very strong,
but are able to withstand significantly more impact than a standard glass
lens. When broken, however, they tend to remain intact as the particles
generally adhered to the centre plastic layer.

Fig. 12.1: Broken laminated glass

Fig. 12.2: PVC film is sandwiched between two glass
surfaces of a laminated glass