SAFETY GLASS

Evening Star, Issue 22805, 13 November 1937, Page 1

SAFETY GLASS

ORIGIN AND DEVELOPMENT A Frenchman named Edouard Benedicts was the first to make a really safe '' glass; He had left a mixture of chemicals in a bottle, and most of the contents had vanished into the air leaving a coating on the side of the bottle. Accidentally dropping the bottle, he was surprised to find that the glass did not break into pieces as ho expected. The fractured sections had been kept firmly in place by the film on the inside. Later, when Benedictus saw the injuries caused by splintered glass in road accidents ho thought of his bottle. He coated a thin piece of glass with a “ celluloid mixture and pressed a similar piece of glass against the celluloid. Safety glass was a fact. This form of safety glass had to be sealed at the edges, after the sheet of glass had been shaped to its actual purpose ; the air and the light had _ a chemical effect on the “ fixing ” mixture between the plates, turning it yellow or brown. But the middle layer has now been improved, and a “ yellow ” windscreen is now rarely seen. The glass has not been altered; a mechanical treatment has simply been added to minimise risk from splintering and cracking. But glass can be toughened so that it can bo struck heavy blows with a hammer without breaking. If it should be too severely tested, instead of splintering it crumbles into tiny pieces like sand or sugar. It will even allow a certain amount of bending without breaking! This type of “tough” glass is sometimes called “ bullet-proof ” glass. That does not mean that it will resist any bullet, no matter how fast or how heavy. , It might stop bullets fired from small pistols, or even rifle bullets from a distance. But even if it does not act exactly as “armour plate ’’ as on a battleship it will not splinter. You may be in danger from a bullet that passes through, but you will not be in danger from the sharp, knife-edged splinters of glass. A type of glass used in many households is called “ fireproof glass.” It is used for dishes that sometimes have to be heated strongly in an oven. This glass may be “ toughened glass ”; but some kinds are made of different materials from ordinary glass, and are “ safe ” even though they have not been toughened. You can make “ fireproof ” and “.toughened” glass _ red hot, and if water is dropped on it it i will not fly to pieces.