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04:00:06 PM Sep 11th 2010
So is this trope about being easy to break through, or just that it leaves a person unharmed?
04:43:14 AM Apr 5th 2010
edited by Galane
Vehicle windshields that shatter and fall to pieces. In the 1940's, most glass used in cars was laminated plate glass. Safer than solid plate glass but still would break into sharp shards, rather deadly if your head hit a window hard enough to punch through, trapping your neck in a ring of daggers held together by an elastic layer of plastic. (Much emphasized in a scene in the Tucker biopic "A Man and His Dream".) The grievous injury potential was reduced so much that all the windows in most vehicles was made of laminated glass. Seat belts, for buyers safety conscious enough to get them installed, averted the potential of 'necklacing'.

When tempered glass was invented, this problem with the previous safety glass was removed and soon all vehicle windows were made of solid tempered glass except the windshields which are laminated tempered glass. Solid tempered glass is the only type in post 1940's vehicles that will shatter and fall to bits when broken.

Yet in most movies and TV shows ALL windows of any vehicle of any year shatter into little pieces and fall out completely when broken. No window made of either type of laminated glass will do that. Starting in the 1960's windshields and rear windows began to be glued in, making it even more impossible for those windows to be removed by gunshots, rocks, being kicked out etc.

So if you're writing a story that involves breaking car windows, please use period appropriate breakage styles. Watch old movies prior to the invention of tempered glass and car windows will break as they should in cars of contemporary vintage. In the reverse, I've seen shows from the 60's where cars that had tempered glass had windows break like non-tempered, laminated plate glass.
04:12:23 AM Apr 5th 2010
They don't use sugar glass much anymore. There's stuff like Smooth-On's Smash Plastic and Rubber Glass which are two part catalyzed resins. They don't need to be melted, are clearer than sugar glass, can be vacuum de-gassed and pressure cast and can be dyed in an infinite range of colors. Another plus is items cast from these plastics can be stored indefinitely with no deterioration until they make their smashing appearance on stage or screen.
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