How Do I Recognize a Dangerous Chip in my Windshield?
There will be a white spot on the windshield: ground glass where the stone hit. Beneath or around that white spot will be an area of black discoloration in the glass; line(s), circle, semi-circle, or in the shape of an eyebrow. That black is air trapped in the glass. Air moves around when disturbed by road shocks or changes in temperature. The glass succumbs to the movement of air by cracking.
Rule of thumb: no black, no crack.
If in doubt, call us. We'll check out your windshield at no cost or obligation.
Once a crack starts, it can be stopped. If not stopped it will continue to the edge of the windshield. The exception is STRESS CRACKS, typically caused by improper installation of a windshield. Cracks caused by stress instead of a stone seem to have minds of their own, and will run through stop measures to the windshields edge.