Cars today use two main types of glass: laminated glass and tempered glass. Laminated glass is the most important part of a car, and has been added to vehicles as a standard safety measure in recent years. It is used for windshields, sunroofs, and side door windows for its increased strength, shatter resistance, and ability to remain transparent even after breaking. The key advantage of laminated glass is that it can withstand serious accidents, and can be repaired with a specialized resin for small cracks.
The main disadvantage is that it is prone to impact breakage and therefore the cost of replacing a new windshield is very high. Tempered glass is cheaper and easier to maintain, which is why many commercial operators still use it on their buses, trucks, and trucks. It has more strength than laminated glass and is less susceptible to breakage by stones or debris. However, it does not have a PVB layer which can prevent a harmful element from entering the car's chamber, and it breaks on impact so it cannot protect occupants.
The front and rear door windows are usually made of tempered glass, while the windshield is made of laminated glass. Automakers began using tempered glass in the late 1930s for its cost-effectiveness. Tempered glass is treated by a rapid heating and cooling process that strengthens the outer surface of the glass and its core. Laminated glass can be traced back to the 1920s when two sheets of glass were placed together using a PVB (polyvinyl butyral) sheet between the layers.
This process induces compressive stress on the surface of the glass and gives it strength and durability far beyond normal glass. At the time of purchase, you can directly ask the manufacturer or supplier about the type of automotive glass you have. But the only solution to repair a broken tempered glass is to replace it with a new one, since it cannot be repaired. An important difference between car or windshield glass and other glass is that the former is shatter proof.
Laminated glass is widely used in the automotive industry, but can be applied for other applications where a potential impact could occur.