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What is Laminated Glass?

Laminated glass is a type of safety glass that is commonly used for automobile windshields because of its ability to bend and absorb impact.
Broken laminated glass.
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  • Written By: Adam Hill
  • Edited By: Bronwyn Harris
  • Last Modified Date: 14 August 2014
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Laminated glass is a kind of safety glass that is commonly used for automobile windshields. It consists of two layers of glass with a layer of film, called the interlayer, in between them. The glass is designed this way in order to prevent it from shattering into sharp pieces when struck by an object or when the car is in an crash.

The interlayer in the glass is a film of a tough, yet pliable material known as polyvinyl butyral (PVB). In the event that the glass breaks, the two layers are held together by the PVB, allowing the sheet as a whole to bend and absorb the impact. This characteristic is especially important for car windshields since, ideally, the film will keep objects from penetrating through the glass and possibly injuring the car’s occupants. Laminated glass is also used in prisons, jewelry stores, hospitals, and other places where safety or security are paramount.

The French chemist Edouard Benedictus invented laminated glass in 1903. As is sometimes the case with inventions, his was inspired by an accident in his laboratory. One of his glass flasks had become coated with a plastic compound called cellulose nitrate. It was dropped, and broke, but it did not shatter into pieces.

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Based on this discovery, Benedictus fabricated a glass-plastic composite that he intended to use to reduce injuries in car accidents. Car manufacturers, however, did not adopt his invention for many years. In fact, the first widespread use of this type of glass was in the eyepieces of gas masks used in World War I. Today, though, it is a much more common sight in a variety of places.

The manufacture of laminated glass has become standardized as demand for the product has risen. Typically, two layers of glass with a thickness of about 0.12 inches (3 mm) are placed on either side of the PVB layer which is 0.015 inches (0.38 mm) thick. Rollers press the layers together to expel any air pockets. The glass is then heated to 158°F (70°C) in a pressurized oil bath to permanently bond all the layers together.

Additional layers of glass and PVB will increase the strength of the material. For example, the glass that forms the front widows of airliners often consists of three sheets of 0.23 inch (6 mm) glass with thick layers of PVB between them. Certain types are also used for artistic applications, such as glass sculptures and mosaics.

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OeKc05
Post 5

@seag47 – The most expensive cars sometimes have laminated glass windows, but typically, cars just have ones made of tempered glass. I'm with you on the safety subject. I would want to be able to break the window of my car in an emergency.

The only downside that I have experienced with tempered glass is that it doesn't do a whole lot to block UV rays. It blocks some of them, but I still get a little bit sunburned if I am driving all day long.

Laminated glass blocks out almost all of the UV rays, so I guess that people driving fancy cars are better protected from the sun. I don't know what they would do if they drove into a lake, though!

seag47
Post 4

Are most car windows made of tempered or laminated glass? I have heard that tempered glass shatters into tiny round bits and it breaks all in one sheet, but since I have never seen a car window being shattered, I'm not sure which material they are made from.

Laminated glass sounds like it would be good for windows because of the insulation and UV protection. However, what if you needed to break it to escape the car? I have this horror of driving off a bridge into water and being unable to get out of the car.

Perdido
Post 3

I have laminated glass windows in my home. They were installed by the previous resident, and I am glad.

They are soundproof, which is a great thing, because my neighbor's dogs bark all night long. If I didn't have these windows, then I wouldn't get any sleep.

They also keep the temperature inside the house from being heavily influenced by the temperature outside. The old house I used to live in would let so much air in around the windows that my air-conditioning bill was astronomical in the summer. I have a lower bill than I've ever had in this house with laminated windows.

DylanB
Post 2

I don't know of any cars in existence today that don't have curved laminated glass windshields. My uncle is a car expert, and he told me that the auto industry started using laminated glass for windshields way back in 1928.

People who got into accidents before then had to deal with shards of glass flying toward their faces. I have had several rocks hit my windshield, and they have only dented a small circle into it. I suppose that every rock that hit the windshields back then probably did major damage.

cevon
Post 1

I own a few laminated art pieces at home, and never realized it was the same type of material as the windshield on my car. I never would have thought of the connection because the mosaics look so fragile.

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