Safer windscreens

Press, Volume CXIII, Issue 33408, 14 December 1973, Page 12

Safer windscreens

Pressure to have new cars fitted with laminated - glass windscreens, rather than the present toughened glass, is increasing in Britain, and has been further fuelled by the announcement of a new and safer type of laminated windscreen glass.

Toughened glass shatters into “sugar crystals” when broken, whereas laminated usually just stars or cracks. The sudden loss of vision which occurs when a toughened screen is broken has been blamed for many accidents. More importantly, British safety experts say, toughened glass causes worse injuries than modern laminated glass when an unbelted passenger is thrown into the windscreen in an accident. With toughened glass, they say, the head penetrates the windscreen, and is then forced down until it is stopped by the last remaining crystals of glass held in the rubber screen surround. It is these crystals that cause serious facial injuries. A modem laminated screen, in contrast, is said to bulge without fragmenting when hit, cushioning the head and preventing lacerations. Laminated screens are already compulsory in the United States, Canada, Italy, Sweden, Belgium, Denmark, and Norway. They cost twice as much as toughened screens, but usually last longer. Nearly all the cars sold

in New Zealand are fitted with toughened glass windscreens. The new British windscreen just announced has been produced by the Triplex company, and the company claims that it will give a hundredfold reduction in facial lacerations compared with even normal laminated screens. It also weighs less, and is much stronger. The new screen is already used in several jet aircraft, including the Concord, and took five years to develop. The secret of the new screen is said to be special thermal toughening of the inner glass surface—on the “interior” side of the flexible plastic interlayer—so that it breaks into toughened-glass type crystals, w’hich are held in place by the plastic layer,

but do not have the sharp edges found in a conventional laminated screen. The Triplex company says ordinary laminated screens are ' safer than thoughened ones, but the new screen is much better than either. Hit by a stone, the new screen acts like a normal laminated screen, and suffers only minor chipping. The new screen has been extensively tested in both Britain and the United States, and several European manufacturers are said to be interested in it.

One British safety authority. Professor G. M. Mackay, recently said that research had shown toughened glass caused four times as many serious injuries as laminated glass.