Windshield glass is different from regular glass and is specifically designed for automobiles. Windshield glass is manufactured in a way to support the structure of a vehicle using different types of safety glass. Safety glass is used in the making of all automobile glass because it reduces the likelihood of injury if it breaks.
The two different types of glass used in making automobile glass are laminated glass and tempered glass. The windshield glass itself is made from laminated glass. In 1927 the automobile industry began using laminated glass by taking two pieces of glass and sticking them together with a transparent piece of plastic called polyvinyl butyral (PVB). The plastic and two sheets of glass are infused by using heat and extreme pressure.
This process keeps the windshield glass from shattering apart during a collision. The windshield is specifically designed to take impact without shattering and provide protection to occupants inside the vehicle. If the occupants of the vehicle are not wearing their safety belts and are thrown into the windshield, the vinyl layer acts as a cushion to the occupant. Since it does not usually shatter, the broken pieces adhere to the plastic lining, giving it a spiderweb-like appearance.
Laminated glass is mainly used in a car where the possibly of human impact can occur. Sometimes it is used on the side windows and back windows of the car as well. Laminated glass can even be used in storefront windows in certain geographical locations where hurricanes are prevalent.
While the side windows and back window of an automobile can be made with laminated glass, they are generally made with tempered glass. Rapid heating and cooling methods are used to manufacture tempered glass. In the event of an accident, or when the stability of the glass is compromised by being hit with an object, the tempered glass will not shatter. Instead, it breaks into tons of tiny pebble-like pieces. These pebble-like pieces are dull and do not cut like regular shattered glass.
Tempered glass can be used for a number of things besides automobile windows. Different examples include outside telephone booths, cooking and baking dishes, polarized sunglasses, and certain cell phone screens. Due to the specific process of making tempered glass, it is harder and stronger than regular glass of the same thickness. Tempered glass is not repairable but laminated glass is. This is why windshield repair is often offered but window repair is not. Windows usually need the entire piece replaced.