In 1903, French chemist Edouard Benedictus was working in his laboratory on other experiments when he accidentally dropped a glass flask that had become coated with plastic cellulose nitrate. When the flask fell to the floor, it did break as you’d expect glass would, but it did not shatter into millions of dangerous tiny shards.
Benedictus saw immediately that his new plastic-coated glass could have many safety benefits. One of the first uses of this new laminated glass was in reinforced eyepieces used for gas masks in World War I.
Later, the automobile industry began using this impact-resistant plastic/glass mix in windshields to reduce life-threatening injuries that commonly occur from shattered glass in car accidents.
Today there are even more practical uses for impact-resistant glass, and it is produced to be even safer. Two or more pieces of glass are layered with a plastic interlayer, typically Polyvinyl Butyral, or PVB. The layered pieces are then sent through rollers to eliminate air pockets and then heated to 158 degrees F in a pressurized oil bath to ensure a tight bond.
The more layers added, the stronger and more impact-resistant this glass becomes. Aircraft windshields are usually three sheets of 6 mm glass with PVB layers between them and bullet-proof glass can be up to 100 mm thick.
This was the first steping stone towards the creation of impact-resistant windows.