What causes the windshield to crack?

Cracks in the windshield can confuse the owner of the most cunning vehicle, especially when there are no external signs of a hole, a splinter or a crack. The next day may bring another alarming revelation; the crack has lengthened and it has crossed the entire windshield, distorting its vision. The answer lies in a few basic physical facts and also some very obvious reasons.

Direct impact, gravel of the route

The most obvious and dangerous cracks in the windshield can be attributed to the random impacts of the route, particularly to gravel, rocks and rocks. They can be kicked behind a vehicle or expelled through the street by a car that passed in the opposite direction. The obvious blows are shown as splinters or large holes, which can extend with primary cracks or “spider webs”. Some small pieces of gravel can leave only a small well or splinter, sometimes microscopic in size, which can be very difficult to detect. These small wells or chips collect moisture and the moisture molecules can expand and contract, pushing the glass in all directions, eventually forming a groove. Such wells and chips, if not repaired immediately,

Structural weakness

Most cracks have their origins very close to the edges of the windshield at a point about 3 inches (7.62 cm) away from the final mold of the windshield. Due to the manufacturing process, a weak point occurs from time to time, caused by a thermal effect during the casting process. Since the glass composition consists of particles and not a liquid substance, the particles do not have a stable grip surface at the edge where the glass does not exist. In addition, the mechanical stress that must be used to force the two pieces of glass together against the inner plastic coating also causes imperfections in and around the edges of the windshield. The very nature of the windshield edge exposes you to more adverse stress, as it joins the windshield mounting gallery at the end.

Extreme cold

Variations in temperature that expand and contract the windshield regularly can produce small cracks that travel along the length of the glass. If the interior air of the vehicle registers 75 degrees (23 ° C) and the external air temperature reads 30 degrees Fahrenheit (-1 ° C), the inner glass layer may expand while the outer glass layer contracts, causing a distortion. Any small defect that exists in the windshield can cause stress and begin to crack. More temperature variation, with the addition of moisture in the windshield, can accelerate the trip of the crack.


A deluge of large hailstones in the shape of stones can hit the glass and cause obvious splits and cracks. What’s worse, multiple blows can pepper the windshield with numerous cracks and sometimes holes, making it useless to repair it. Hail damage can be infrequent, but when present it can be devastating to all glass panels in the vehicle.

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