CRACKED WINDSHIELD Q&A

Question: How do long cracks start?

Answer: Over 90 percent of the time, long cracks start with a single chip close to the edge of your windshield… in the black edge — the “frit” — of the glass, so you can’t see it until it has started to crack.

Q: Why the edge of the glass?

A: That’s the weakest part of the windshield. The frit is placed on the glass to keep the sun’s ultraviolet light from cooking the polyurethane seal that holds the glass to the frame of the vehicle.

But because it’s black, the frit gets very hot in the sun. There is often a 20-30 degree difference in temperature between the center of your windshield and the edge. This tends to make the edge of the glass brittle, and make it more susceptible to stone chips that turn into cracks.

Q: Why should a crack be fixed promptly?

A: If a crack is more than about a month old, it tends to get dirty. The windshield wipers tend to push dirt into the crack over time. And when it rains, dirt is carried into the crack.

If a crack is caught early enough, however, a good repair can be done that will accomplish three things:

Stop the crack from spreading.

Restore much of the strength of the glass.

Make the crack much less visible.

Q: Can two or more separate cracks in a windshield be repaired?

A: A windshield with two or more cracks should be replaced, both from a visual and from a safety point of view.

Q: What does a long crack repair look like if done properly?

A: The best of repairs will look like a hair lying on top of the glass. The glass has been damaged so the crack won’t disappear. It will greatly reduce the “glinting” of an open crack when the sun hits it.