Bénédictus glued a plastic film between glass so it would not shatter

In 1903 French chemist and painter Édouard Bénédictus clumsily dropped a glass flask on the floor of his laboratory. It shattered, but instead of flying into pieces, the fragments stayed together. When he examined it, he found the flask had previously held an alcohol solution of collodion — a plastic made by treating cotton with sulfuric and nitric acids — and when the solvent evaporated, a thin film of plastic had been left on the inside of the glass.

Bénédictus found the observation interesting but set it aside. What changed his mind was reading a story about a young girl being cut by glass shards in one of the first automobile accidents. Glass that broke into flying shards was a serious danger on early cars, and Bénédictus began to think about how the flask's behaviour could prevent it.

He spent the night working out how to make the coating, and within a day had produced the first sheet of safety glass: a sandwich of two sheets of glass with a film of cellulose nitrate between them. He named it triplex, because of its three layers. Even if the glass broke, the plastic layer held the pieces in place, so they could not fly out and cut anyone.

He applied for a patent in 1909, and triplex went into production. Its first practical use turned out to be the face shields of World War I gas masks, but by the 1920s it became standard in American automobile windscreens.