Chip repair is the best value in auto glass and the job people delay longest, which in this climate is exactly backwards.
Why Michigan is unusually hard on chips
A stone chip is a small void in the outer layer with a network of cracks radiating from it. That void takes on water. Water expands about nine percent when it freezes.
Metro Detroit runs through the freeze-thaw line repeatedly from November to March — above freezing in the afternoon, well below it overnight, sometimes several times in a week. Each cycle levers the crack a little further open. Then you start the car on a cold morning, put the defroster on full, and heat one side of the glass while the other side is still at outside temperature. That is when chips run, and it usually happens all at once.
The practical version: a chip that appears in October and is ignored is very often a replacement by February. The same chip dealt with in October is a half-hour job.
The three tests
| Test | Repairable | Replace |
|---|---|---|
| Size | Chip under a quarter; crack under a dollar bill | Anything larger |
| Position | Outside the driver’s direct view, away from the edge | In the sweep of vision, or touching the edge |
| Depth | Outer layer only | Through to the inner layer, or both layers |
Position is the one people argue with. A repair leaves a small amount of optical distortion. Directly in front of the driver, that distortion is a worse problem than the chip was, especially at night in rain against oncoming headlights. Refusing to repair a chip in the driver’s view is not upselling. It is the reason the rule exists.
Edge damage is the other one. The perimeter is where the glass is bonded and where the structural load sits. A crack that reaches the edge has compromised that, and it will run.
Where the chips come from around here
- Gravel and aggregate hauling on I-75, I-94 and I-96, especially through construction seasons
- Winter road treatment — the sand and slag mixed into salt on metro freeways is exactly the size that chips glass
- Freeze-thaw damage on surface roads producing loose aggregate long after the potholes are patched
- Following distance in stop-start traffic, which is where most windshields get hit at speed
What the repair actually is
The break is cleaned and dried. A bridge is clamped over it and a vacuum drawn to pull the air out of the crack network — that step is what separates a repair that holds from one that clouds later. Resin is injected under pressure, cured with UV light, and the surface is scraped flat and polished.
Done properly it restores the structural integrity of the outer layer and stops propagation. Done in a hurry, with moisture still in the break or without pulling a proper vacuum, it traps air, looks worse than the original chip and fails anyway.
Multiple chips
Common on cars that spend time behind trucks. Several chips can usually be repaired in one visit, and the per-chip cost normally falls after the first. There is a point where the count itself is the problem — a windshield with numerous repairs in the driver’s view has accumulated enough distortion to be worth replacing on its own merits. That is a judgement call and you should be given it honestly rather than sold either way.
When to just replace it
Be suspicious of a shop that will repair anything you bring them. There are cases where a repair is the wrong answer and taking your money for it is the wrong thing to do:
- The crack already reaches the edge
- Damage runs through to the inner layer
- It sits in the driver’s primary field of view
- There is contamination in the break — wax, water, glass cleaner from an attempted DIY kit
- The car has a camera behind the glass and the damage sits in the camera’s field of view
Common questions
How do I know if my chip is repairable?
Three tests. Size: smaller than a quarter for a chip, shorter than a dollar bill for a crack. Position: not directly in the driver's line of sight, and not touching the edge of the glass. Depth: damage to the outer layer only, not through to the inner layer. Fail any one of them and replacement is the honest answer.
Will the chip disappear?
No. A good repair fills the break, restores the strength and stops it spreading, and what is left usually looks like a faint blemish you have to know about to find. Anyone promising invisible is selling. Expect roughly 70-90% cosmetic improvement, and judge the job on whether the crack stops running.
Will my insurance cover a repair?
Frequently, and often with the deductible waived or reduced, because a repair costs the insurer a fraction of the replacement it prevents. That is insurer economics, not Michigan law — the state has no free-windshield statute. Worth one phone call to your carrier before you decide to pay out of pocket.
Can you repair a chip in the cold?
Within limits. Resin needs to flow into the break and cure, and both are temperature dependent, so a windshield at fifteen degrees needs warming first and a wet one needs drying. In a Michigan winter this is the difference between a repair that holds and one that fails in a month. If conditions are wrong on the day, you will be told rather than sold.
How long does it take?
Usually under half an hour per chip once the car is accessible. It is the kind of job that happens in an office car park while you work, which is most of why people put it off less than a replacement.