The scenario is all too common: You're driving along the Interstate minding your own business, a muddy gravel truck pulls in front of you and moments later a stone comes smacking against your windshield, leaving a whitened, pitted scar.
But wait, there's still hope! Often, a simple repair to stone damage will prevent the wound from sprawling across the windshield, into your field of vision, and way into your wallet. To increase your chances that your damaged windshield might be repaired rather than replaced, consider the following guidelines:
If you can cover it with a quarter, it might be repairable. As a general guideline, smaller pits (less than an inch in diameter that don't go too deep) can usually be repaired with a resin-based material professionally injected into the damaged area (as long as they're not in the driver's line of sight). The new material is then often cured through a process involving exposure to high-intensity ultraviolet light. Sometimes longer cracks can be repairs, provided they don't meet the edge of the windshield in more than one place.
Limit your driving. Try to drive as little as possible before you take your vehicle to a glass shop for an inspection. Vibration and temperature changes can quickly cause small cracks or pits to sprawl out over the whole windshield.
Prevent the damage from contamination. Lightly apply a piece of transparent cellophane tape or packing tape over the impact point to prevent dirt and debris from getting into the pit.
Do not touch the damage. Besides being sharp, oils from your skin will reduce the effectiveness of a repair, and the slightest touch might cause a crack to expand.
Don't slam your doors, the trunk, or the hatch firmly. The vacuum inside the car creates a sudden stress on the windshield's seal. Keeping one window slightly cracked will avoid this stress.
Temperature changes might make the damage worse. Avoid getting the glass wet if possible, and try not to run the defroster. Either of these might encourage cracking due to the temperature differences on either side of the glass. Avoid parking in direct sunlight for the same reason -- consider parking in a garage until you get it repaired.
You know how to keep the damage under control. Now here's what to do:
Bring the windshield to a glass shop as soon as possible. Windshield repair is not for novices, and only a reputable professional automotive glass shop (or sometimes your dealership) can tell you if your windshield can be repaired or if it must be replaced. Ask your regular mechanic for a recommendation.
Do-it-yourself doesn't work on windshields. You might be tempted by the cheap fix-it kits available at auto-parts stores and department stores. These often usually include a resin compound that bonds with the glass, and a small syringe-suction-cup contraption to inject the compound into the damaged area. The material in these often yellows with time and weakens. These kits often yield undesirable results, and once they've been used the windshield can no longer be professionally fixed. Save money, and preserve your safety.
Then there's the safety aspect. Windshields are functional members of modern unit-body automobiles, providing stiffness, rigidity, and crash protection for the body. Most front airbags are designed to work with the original windshield seal. If a windshield has been replaced and the seal has been broken, then the airbag might no longer be optimized for a deployment. If minor, small windshield damage is fixed early, then there is often no breach in the seal and the windshield suffers no reduction in strength.
Use OE-approved glass. Finally, if you must replace the windshield, it's of utmost importance that you request the use of original-equipment quality glass. Many glass shops now offer budget-priced glass made in China that does not necessarily have the strength of the original windshield.
The bottom line is that catching and repairing windshield damage when it happens -- and having it fixed while it's still small-can save you hundreds of dollars. Fix it now before it costs many times as much.