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From a Broken Flask: Laminated Safety Glass

All About Glass

Edouard Benedictus, a set and costume designer for a French theater, wanted to make glass safer. He was disturbed by reports of people being disfigured by broken windshield glass during automobile accidents. How could windshields be made less dangerous?

He recalled a curious incident that had happened years earlier, when he was pursuing his interest in chemistry. He had dropped a seemingly empty glass flask, and it broke. To his surprise, the pieces stayed together. The liquid that had been in the flask had evaporated and left a thin plastic film, which held the pieces of glass in place.

Bénédictus concluded that windshields would be safer if they were made from glass that held together after it broke. In 1909, he patented TriPlexTM, a laminate made from two glass sheets bound to an inner layer of clear plastic. Today, every car, truck, and bus built in the United States has a windshield of laminated safety glass.

Early car with unlaminated windshield
laminated glass

Making a Laminated Windshield

Laminated safety glass

A laminated glass windshield starts out as three distinct layers: two perfectly matched transparent glass sheets and an opaque plastic sheet.

The plastic interlayer is placed between the two pre-shaped glass sheets, and the entire assembly is subjected to heat and pressure. The plastic turns transparent and adheres to the glass, forming a three-layer windshield.

The Corning Museum of Glass
This article was originally published in Innovations in Glass, 1999, pp. 18–20.

Published on October 25, 2011