A Finished Repair Looks Great, but Later the Chip Seems to Reappear

Question:

When I finish a repair, it looks great, but later the rock chips seems to reappear, what is happening?

Answer:

There are two common causes for this problem, the most common of which, is over-heating. While warming the glass to 70 to 100 degrees can be very beneficial, heating the glass past that point causes the glass to expand, pushing the resin out of the crack. It looks repaired but in fact has no resin in the cracks, thus no bonding strength. When the glass is cooled, it contracts and the cracks reappear. To test this theory, heat a rock chip on a piece of scrap glass without putting any resin in it. Small chips and cracks will often disappear. Now cool the glass and see what happens.

The second most common reason for this issue is putting too much pressure on the windshield when affixing the repair fixture “bridge” or injector holding device to the windshield. If the injector is over tightened, the glass will flex in and the cracks will close just as when over-heated. To eliminate this problem, once the injector seal has made contact with the glass, rotate the injector one half turn, then make your final leveling adjustments with the rear adjusting screws.