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Charlie Stephens · 10-04-2013, 08:13 PM

There are two types of safety glass. Today we use tempered glass everywhere in a car but the windshield. This glass is made by heat treating the class after it is cut. The glass is brought almost to a molten temperature. It is then hit with a blast of cold air to solidify the surface. As the interior cools it contracts. This sets up stress within the pane of glass. This stress causes the glass to break into thousands of harmless pieces when it is broken. In case of an auto accident the glass in the side windows can be broken with a sharp rap to reach passengers trapped inside. It is also probably cheaper to manufacture than the laminated. This glass in the windshield is laminated. There are two pieces of glass sandwiched around a plastic (acetate) core that keeps the glass from breaking into dangerous pieces. The tempered glass is not used in the windshield because you wouldn't want a windshield to shatter into a thousand pieces if hit by a rock on the freeway.The glass in the '40 was the same type that is used in windshields today.

Charlie Stephens

10-04-2013, 08:13 PM	#2
Charlie Stephens Senior Member Join Date: May 2010 Location: Southern California Posts: 7,031	Re: double paned glass in a 40 There are two types of safety glass. Today we use tempered glass everywhere in a car but the windshield. This glass is made by heat treating the class after it is cut. The glass is brought almost to a molten temperature. It is then hit with a blast of cold air to solidify the surface. As the interior cools it contracts. This sets up stress within the pane of glass. This stress causes the glass to break into thousands of harmless pieces when it is broken. In case of an auto accident the glass in the side windows can be broken with a sharp rap to reach passengers trapped inside. It is also probably cheaper to manufacture than the laminated. This glass in the windshield is laminated. There are two pieces of glass sandwiched around a plastic (acetate) core that keeps the glass from breaking into dangerous pieces. The tempered glass is not used in the windshield because you wouldn't want a windshield to shatter into a thousand pieces if hit by a rock on the freeway.The glass in the '40 was the same type that is used in windshields today. Charlie Stephens Last edited by Charlie Stephens; 10-05-2013 at 03:33 AM.