Bullet proof glass

Bullet proof glass is usually fabricated using polycarbonate thermoplastic or layers of laminated glass. The aim is to make a material with the appearance and clarity of standard glass but with effective protection from small arms fire. Polycarbonate designs usually consist of plastics sandwiched between layers of regular glass.

The plastic in laminate designs provides resistance to impact from physical assault from hammers, axes, clubs, and so forth. The plastic provides little in the way of bullet-resistance. The glass, which is much harder than plastic, flattens the bullet, which prevents penetration. This type of bullet-resistant glass is usually 70-75 millimetres (2.8-3.0 inches) thick.

Laminated glass layers are built from glass sheets bonded together with polyvinyl butyral, polyurethane or ethylene-vinyl acetate. This design has been in regular use on combat vehicles since World War II; it is typically 100-120 millimetres (3.9-4.7 inches) thick and is usually extremely heavy.