Today’s automotive windshields are not simple composed of glass as the name might suggest. Modern windshields are made from laminated safety glass that include two layers of glass sandwiched around a layer of PVB (polyvinyl butyrate). This is for safety reasons. During a crash or other occasion when the windshield is damaged, sharp pieces of glass will tend to stick to the PVB layer. This decreases the potential danger from flying glass, to passengers in the cabin of the vehicle. The PVB layer in laminated glass also serves to protect passengers and keep them inside the vehicle during collisions by exerting a cushioning effect.
Heat strengthened, alson known as tempered, glass is considered to be a form of safety glass as well. This type of glass is commonly used in vehicle side and back windows as opposed to windshields. Tempered glass crumbles into rounded glass pebbles which are relatively harmless, when broken.



