Glass & Visibility · DIY Guide
How to Use a Windshield Repair Kit to Fix Chips and Small Cracks
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A small stone chip can turn into a long crack after a few cold mornings or a pothole. Fixing it early with a resin repair kit takes about an hour, costs very little and keeps dirt and moisture out of the damage. Here's how to do it properly, and how to tell when a chip is too big for DIY.
Key takeaways
- Repair chips as soon as possible, before dirt and moisture get in.
- DIY kits work best on small chips and bullseyes, roughly the size of a quarter or smaller.
- Long cracks, damage in the driver's line of sight, or damage at the edge of the glass need a professional.
- Work out of direct sun to fill the chip, then use sunlight or UV to cure the resin.
Can Your Chip Be Repaired?
DIY kits are designed for bullseyes, star breaks and combination chips that are small (generally under about an inch across) and haven't spread into a long crack. Follow your kit's size limits. Get a professional repair or replacement if:
- the crack is longer than a few inches or still spreading;
- the damage is directly in the driver's line of sight;
- it's within a couple of inches of the edge of the glass;
- it goes through both layers of glass, or there are several chips close together.
Many auto insurance policies with comprehensive coverage pay for professional chip repair with little or no deductible, so it's worth checking.
How to Repair a Windshield Chip Step by Step
- Park in the shade. Resin cures in UV light, so do the filling out of direct sunlight on a mild day. Avoid very hot or freezing glass.
- Clean the damage. Use the pushpin from the kit to remove loose glass from the impact point, then clean the area with glass cleaner and let it dry completely. Don't use water or cleaner inside the chip itself.
- Attach the applicator. Center the applicator or pedestal over the chip so the tip sits directly over the impact point, and press it down firmly so it seals.
- Add resin and create pressure. Add the number of drops your kit specifies, then screw in the injector or plunger to force resin into the cracks. Some kits alternate vacuum and pressure cycles to draw out air.
- Wait for it to fill. Leave it for the time in the instructions. You'll see the chip become less visible as resin fills it.
- Remove the applicator and add a curing strip. Put a drop of resin on the chip, cover it with a curing film and smooth out air bubbles.
- Cure in sunlight. Move the car into direct sun (or use a UV lamp) for the time stated, often 5–15 minutes.
- Scrape and clean. Peel off the film, scrape off excess cured resin with the razor blade held at a shallow angle, then clean the glass.
Common Mistakes to Avoid
- Filling the chip in direct sunlight, which cures the resin before it penetrates.
- Leaving water or cleaner inside the chip.
- Not seating the applicator tightly, which lets air back in.
- Waiting weeks before repairing, by which time dirt has filled the break.
- Using the defroster or car wash right after a fresh repair; follow the kit's cure time.
Windshield Repair Kit We Recommend
This popular kit includes the applicator, resin, curing strips and blade you need for small chips.
- Best DIY kitPermatex 09103 Windshield Repair KitResin kit for small stone chips and bullseyes; follow the curing instructions exactly.Check Price
Frequently Asked Questions
Do windshield repair kits really work?
Yes, on small chips and bullseyes. A good kit fills the break with resin, which stops it spreading and makes it much less visible. They don't work well on long cracks.
How big a crack can a DIY kit fix?
Most kits are intended for chips up to about an inch across and very short cracks. Check your kit's instructions, and have longer cracks repaired or replaced professionally.
How long does a windshield repair last?
A properly cured resin repair is permanent and should last for the life of the windshield.
Can I repair a chip in the cold?
Resin flows and cures best on mild glass. In cold weather, park in a garage to warm the glass or use the defroster gently first, then let it cool to a comfortable temperature before repairing.
The Bottom Line
Fix chips quickly, work in the shade, and cure in the sun. For anything larger than a small chip, a professional repair or replacement is the safer choice. While you're improving visibility, make sure your wipers are in good shape with our wiper replacement guide.