When it comes to building cars, two main types of glass are used: laminated glass and tempered glass. Tempered glass is designed to fracture into small, less dangerous pieces in order to avoid serious injuries caused by sharp edges. Most of the glass used in cars is tempered, including the side windows, the deflector glass, the ventilation glass and the glazed roof (if the car has one). However, the most important glass in any vehicle is the windshield, which is made of laminated glass.
Laminated glass is a century-old fool-proof design that consists of two strong sheets of glass that become a single thick sheet by sandwiching a layer of polyvinyl butyral in the middle. These layers bond at high temperatures to provide us with incredibly strong and durable automotive glass that won't break in the event of an accident. The tempering process induces compressive stress on the surface of the glass and gives it strength and durability far beyond normal glass. Different types of glass are used throughout the vehicle because each type of glass has a different purpose.
But the only solution to repairing a broken tempered glass is to replace it with a new one, since it cannot be repaired. Unlike tempered glass, laminated automotive glass is designed to tolerate heavy impacts during a crash or collision. If you're not sure if a piece of automotive glass is tempered or laminated, simply read the manufacturer's label. Tempered glass is manufactured by rapidly heating it to more than 1000 degrees Fahrenheit and then rapidly cooling it to room temperature.