Windshield Chip or Crack: Repair It or Replace the Glass?

A rock kicked up by a gravel truck doesn't announce itself. You hear a tick, find a little star in the glass, and tell yourself you'll deal with it later. Later is usually a cold morning or a pothole, and by then the star has grown a crack that runs across the windshield. Knowing what a repairable chip looks like lets you act while the fix is still a small one.

What a chip repair actually does

A chip repair is a resin job. The technician cleans the damaged spot, sets a small tool over it, pulls the air out with a vacuum, and lets clear resin flow into the break. Ultraviolet light cures the resin, and the surface is then scraped flush and polished. The glass is not made new. What you get is a break that is filled, sealed, and strong enough that it won't spread.

Expect a faint mark where the chip was. An honest shop tells you that up front, because the goal is stopping the damage and keeping your original windshield, not making the chip disappear. Your windshield is bonded into the body opening and carries part of the structure of the car, so keeping the factory glass whole is worth something.

When a chip can usually be repaired

Rules of thumb vary a little from technician to technician, but the pattern is consistent. These are the signs that point toward a repair.

• The damage is about the size of a coin or smaller
• The break hasn't reached the edge of the glass
• It sits outside the driver's direct line of sight
• Only the outer layer of the laminated glass is damaged
• Any cracks running off it are short, a few inches at most
• It's fresh, with little dirt, water or washer fluid worked into it

Windshield glass is two layers with a plastic film between them. A chip that stays in the outer layer is a good repair candidate. Once the damage goes through to the inner layer, resin can't do the job anymore.

When the glass needs replacing

Some damage is past the point where filling it makes sense. A repair that fails later costs you twice, so a good shop will say so plainly when replacement is the honest answer.

• A crack longer than a few inches
• Damage that reaches the edge of the windshield, where cracks travel fastest
• A chip directly in front of the driver, because even a good repair leaves slight distortion
• Several chips close together
• Damage to the inner layer of the glass
• Cracks or chips around a camera or sensor mount

Edges are the weak spot. The glass is held and stressed most at its perimeter, and temperature swings do the rest. A crack that starts near the edge can run the full width of the windshield overnight.

What to do until you can get in

A few small habits keep a repairable chip repairable. Put a piece of clear tape over the chip so dirt and moisture stay out. Skip the pressure washer and the automatic wash with the brush rollers. Don't slam the doors, because the pressure pulse can push a crack along. And if the windshield is frozen, don't aim the defroster on high at cold glass. Warm it gradually. Sudden heat on a chip is a common way to turn it into a crack.

The sooner a chip is filled, the cleaner the result. Resin flows into a fresh break easily. After weeks of road grit and rain, the break holds contamination, and the repair looks cloudier even when it still stops the spread.

What happens when the glass is replaced

Replacement starts with removing the old windshield, then cleaning and priming the bonding surface on the body. A fresh bead of urethane adhesive goes down, the new glass is set into it, and the trim goes back on. Then comes the part people forget: the adhesive needs time to cure before the car is asked to do anything demanding. Ask how long before it's safe to drive, and follow the answer.

After you leave, don't pull at the tape or trim holding the glass in place, and ask when it is fine to wash the car. If your car has a camera or sensor behind the windshield, ask whoever does the work how it's handled. It's a fair question to put to any glass shop.

Glass work at Ron Kirk's

Ron Kirk's Body Shop repairs windshield chips and replaces windshields and other auto glass on all makes and models. The shop also runs a local shuttle service, so you don't have to sit in a waiting area while the work gets done. That helps when the glass job is happening on a workday and you have somewhere to be.

The shop is also a full body shop, so if the thing that cracked your windshield also dented your hood, both can be looked at in the same visit. Estimates are free, and hours are Monday through Friday, 8:00 am to 5:00 pm.

Small chips are the easiest repair there is, and the one most often put off. If you've got one now, today is a good day. Ron Kirk's Body Shop is at 501 Vermont Ave in Holton, and the number is (785) 364-2931.