Why windshield cracks in winter
Windshield technology has improved considerably in recent years. Plain, flat glass window in the first automobiles left its place to tempered glass, which broke into pieces when it broke, but not sharpened pieces. As early as 1919, Henry Ford began experimenting with laminated glass – two panels that interspersed a layer of cellulose.
The glass would break, but not break into pieces. The father of American automobile manufacturing ordered the use of laminated glass in all Ford cars by the 1929 laminated windshield. The first ones remained stable. Modern windshields are curved. Modern laminated windshields also use polyvinyl butyrate as the filler between the two pieces of glass. It is the safest windshield glass in motion.
It is not uncommon for small stones to be thrown on your windshield while driving. You may not notice the tiny chips that spoil the surface of the windshield – until the external temperatures fall below zero and a barely visible chip suddenly develops in a crack. You can aggravate the situation by defrosting your windshield by pouring hot water into it.
According to seismologist Larry Gender, the problem is caused by the metal structure of the car expanding and contracting (with temperature changes) at a different speed than the windshield glass. This causes additional stress on the glass in cold weather, especially at the tip ends of a crack, resulting in serious risk of further separation.
Prevention / Solution
Rick Robertson, vice president of Auto Glass, gives the following advice: have existing chips fixed before winter. Do not turn the vehicle’s defrosting windshield to the maximum as soon as it exits your garage; rather, warm gradually to minimize temperature differences on freezing days.