How does repairing a chipped windshield work?

March 22, 2025 9:46 AM

Got two small knicks on my windshield, under a penny in size. Made an appointment to get them repaired. Once at repair shop for appointment, was informed that their work would stop the cracks from spreading, but the knicks themselves may still be visible. Is that common? To have the crack/knick still be visible? I thought the knick would be totally repaired (without replacing windshield) but have never had to have this type of repair. This is out of pocket, no insurance involved, for $160 US
posted by clocksock to Technology (8 answers total)

Yeah, that's just how glass works. Once it's broken, it's broken. But keeping it from spreading can be a big deal, especially if you have the kind of windshield with built-in heating wiring that's a lot more expensive to replace.
posted by Lyn Never at 10:00 AM on March 22 [3 favorites]

And for a rapidfire overview of some dozen-ish products, Project Farm did a video of a bunch of DIY kits and how they work. Mostly I suspect the repair shop is doing some CYA - not all cracks and knicks are always going to be fully repairable and under the right conditions you may still be able to see it, so you gets what you pay for sorts of deals.
posted by Kyol at 10:06 AM on March 22 [2 favorites]

Yes, it'll probably be barely detectable if it's a small shallow knick, but you'd be upset if they didn't warn you ahead of time.
posted by michaelh at 10:09 AM on March 22 [2 favorites]

Yup. They fill in the cracks with some kind of glue/epoxy/filler substance and then seal it under suction to fully fill it in. Kind of cool to watch if they let you. You'll still see it but it keeps it from spreading.

Unfilled cracks are particularly a concern if you live in a place with a freeze-thaw cycle. Other things that cause unfilled nicks/cracks to spread are potentially the jets of the carwash if they hit it just right, or a second piece of debris hitting near the same place, or going over a serious bump.

Check with your insurance, if you bill with them (but pay out of pocket because it's under the deductible amount) they sometimes will give you a little discount because it's cheaper to keep on top of window nicks than it is to replace the window, for most cars with the built-in defroster or sensors in there. Sometimes there's a working-with-insurance price and a cash price and it's worth it to ask the glass people if there's a difference.
posted by blnkfrnk at 10:22 AM on March 22

There are some parts of the windshield where the repair might be more or less visible, too. I chipped my windshield on the "frit", the dark dots around the edge, and the repair guy told me a repair there was unavoidably going to be visible because of the composition of the glass. Which it is. But I've certainly seen repaired chips in other parts of the windshield where you have to look pretty hard to see where the repair was. There's a part of the windshield that looks a little smudgey but you can't tell there was a break in the glass.
posted by potrzebie at 10:44 AM on March 22

Yes, common. My visible nick has been there for 14 years and has not spread.
posted by dabadoo at 11:21 AM on March 22

Also agreeing, the commercials that make it look like "where did the crack go?" are 100% perfect-case-never-actually-happens situations. My minivan has a 3 or 4 of tiny cracks, about the width of my pinky fingernail, that are clearly visible and will catch the sunlight at the right angle, but the cracks haven't grown, and that's all they promise.

My insurance covers these for free, despite a deductible for windshield repair.
posted by AzraelBrown at 3:17 PM on March 23 [1 favorite]

Yep, the disclaimer about "you may still be able to see it" is totally normal and IMO something you'll hear from any responsible glass-repair place.

In my experience though, the cracks are much less visible once they've been filled with epoxy and repaired. You can sometimes see them depending on the angle, but it's absolutely worth doing if you can catch the crack while it's still small enough to be effectively repaired.
posted by Kadin2048 at 8:12 PM on March 23