Causes of Stress Cracks in Windshields

Replacement of windshield auto glass in Saint Paul, MN, typically is necessary when the windshield develops a crack; although some drivers continue traveling with a relatively minor crack for quite some time. Cracks are usually caused by a hard object hitting the windshield. This could be a rock thrown from a flatbed truck or a golf ball that went completely astray. In other cases, a crack suddenly appears seemingly out of nowhere. These are stress cracks that develop for certain reasons.

Manufacturing Defects

People generally don’t think of glass as ever being soft. However, during windshield manufacturing, glass must be heated to a high temperature, so it becomes flexible. Technicians can then form it into the proper shape for a vehicle. A gradual cooling process heightens durability of the glass, but the glass may still have a certain degree of weakness at the edges. This can eventually lead to a crack developing, requiring a need for replacement auto glass in Saint Paul, MN.

Installation Defects

The combination of a manufacturing defect and an installation defect make the windshield significantly more vulnerable to fracturing. If the technicians did not make sure the pressure was even around the entire windshield, the uneven pressure can cause a crack when the temperature rapidly changes from cold to hot or vice versa. Metal and glass both expand in heat and contract in cold temperatures, but they do so at different levels.

Consider that it’s often possible to open a glass jar with a metal lid that is too tight by holding the top of the jar under hot running water. The metal expands to a greater extent than the glass does. When this occurs in a windshield and frame, uneven pressure at the edges can result in a crack.

Sudden Temperature Changes

Pouring hot water on an icy windshield can cause a stress fracture, and pouring cold water on a hot windshield can do so as well. That’s because the glass expands or contracts rapidly where the water hits, but the rest of the windshield remains static. This can occur if someone tries to remove ice with hot water or starts washing a sun-baked car with cold water from a garden hose. Companies like Harmon AutoGlass provide mobile service to replace the windshield.

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