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Understanding Automotive Glass

tempered auto glass

Because moving vehicles must withstand air pressures, high speeds, and impacts, automotive glass is specially designed to be strong and provide added safety to automobiles. Although it may look just like regular window glass, auto glass is processed to have very different properties.

The windows in modern vehicles are made of two different kinds of automotive glass:  Tempered Glass and Laminated Glass.

Tempered Glass

This special, heat-treated glass is used in the side and rear windows of automobiles such as cars, vans, and pickups. Before being heat-treated, normal window glass is easily shattered, and can break into sharp and deadly shards under impact or severe pressures. Early automobiles had plain window glass, which caused many fatalities and serious lacerations when these vehicles were involved in collisions. To correct this grave flaw, auto producers developed the process of tempering auto glass.

In the tempering process, sheets of glass are superheated – to temperatures of over 600 degrees Fahrenheit – and then cooled very rapidly with bursts of cold air. This process makes the glass contract, so that it is far denser.

The density of tempered glass means it is stronger, and far more resistant to fluctuations in temperature. Even more importantly, upon impact, tempered auto glass will break apart into dull-edged chunks – rather than sharp, pointed pieces – to protect passengers from lacerations if a window is shattered in a collision.

Due to these special properties, tempered glass auto windows cannot be repaired if they are broken. They must be removed and replaced.

Laminated Glass

Because the windshield of a car or truck not only protects passengers but acts as a part of the vehicle’s structural support, an even stronger type of glass is required for this important car window. Unlike tempered glass which – while durable – may still shatter into pieces if impacted by another object, the laminated glass used in windshields is designed to withstand much more, and to remain in one piece even if it is cracked or broken.

Laminated glass is created by sandwiching a thin layer of clear vinyl – called polyvinyl butyral – between two sheets of glass. The three layers are then sealed with pressure and intense heat, bonding the glass and PVB into one thick and impact-resistant sheet.

Unlike tempered glass windows, a windshield can often be repaired instead of replaced when it has been cracked or chipped by an impact. If your windshield’s structural integrity is intact, we can use a high-tech process to refill and seal chips and cracks. During the process, we utilize a “vacuum” to remove any air that has entered between the glass and PVB layers, then completely fill any openings with a strong clear resin. Once we have achieved complete saturation, we undertake a curing process until the resin has solidified. The entire crack or chip repair process usually requires only half an hour.