Windshield Repair Quality Checklist
The short answer
- Judge the shop before the work starts. A tech who inspects, photographs, classifies the break and states the repairability limits out loud is telling you they follow a procedure.
- The single most diagnostic thing to watch for is a vacuum cycle. Resin pushed in under pressure alone traps air in the legs, and trapped air is the leading cause of a repair that runs later.
- A correct repair takes roughly 20 to 40 minutes for a single break. A five minute job is pit resin smeared on the surface, not a filled break.
- Inspect the finished work outdoors at about a 45 degree angle, and run a fingernail across the pit. It should be smooth and flush with the glass.
- Score the visit out of 20 using the rubric below. Under 9 means ask for a redo or take the warranty credit toward replacement elsewhere.
You cannot judge a windshield repair by the price or the sign on the van. You can judge it by watching a short, specific list of steps, and by how the finished pit reads in daylight. This checklist splits the visit into three phases, before, during and after, and ends with a 20-point rubric you can score in real time.
Phase one: before the work starts
Everything that determines whether the repair succeeds is decided here. A tech who skips straight to the bridge has not decided whether your break should be repaired at all.
- They inspect the break properly. Expect them to look from outside and from inside the cabin, ideally with a light held at an angle. A quick glance from six feet away is not an inspection.
- They photograph it. Good shops document the break before work. It protects them and it protects you.
- They classify it out loud. Bullseye, star break, combination break, half moon, or a crack. If they cannot name the pattern, they cannot judge the fill strategy it needs.
- They measure edge distance. Damage within about two inches of the glass edge sits in the highest stress zone and is normally a replacement, not a repair. See edge cracks.
- They check the driver's primary viewing area. A repair leaves a permanent blemish, so a break directly in your sightline deserves a conversation before, not after.
- They check the inner layer. Pressing gently from inside, or looking with a light, tells them whether the inner ply is also cracked. If it is, resin repair is off the table because injected resin only reaches the outer ply.
- They state the limits. A straight sentence like "this will stop it spreading, you will still see a faint mark, and there is a chance it runs while I work" is the mark of an honest tech, not a hedge.
- Price and warranty are stated in writing before work begins. Including what happens if the break spreads later, which for most shops means crediting the repair price toward a replacement.
Stop here if: the tech proposes repairing a crack that crosses your line of sight, offers to repair damage touching the glass edge, or will not commit to a price and warranty before starting. Any of those three is enough to walk away. If you are not sure your damage is repairable at all, check it against the repair or replace tool before the appointment.
Phase two: during the repair
You do not need to hover, but stand where you can see the windshield. The steps below are the ones that separate a filled break from a cosmetic smear. For the underlying process, see how chip repair works.
| Step | What you should see | Why it matters |
|---|---|---|
| Glass conditioning | The break area is dried and cleaned. If it has been wet, a moisture evaporator or gentle heat is used. Glass brought into a workable temperature band, shaded from direct sun. | Resin will not bond to a wet or contaminated fracture face. Direct sun starts curing resin before it finishes flowing. |
| Pit preparation | Loose glass at the impact point is carefully removed, sometimes with a light probe or a small carbide bit. | Loose fragments block the injector opening and hold air. |
| Bridge mounting and seal | Suction cups or an adhesive mount set square over the pit, with the injector seal pressed flat against the glass and no visible gap. | A leaking seal makes vacuum impossible. This is where most poor repairs go wrong. |
| Vacuum cycle | The tech pulls the plunger or opens the vacuum position and holds it. You may see tiny bubbles rising out of the legs. | Removes trapped air so resin has somewhere to go. Skipping this is the single most common shortcut. |
| Pressure cycle | The plunger is driven down and held, often for several minutes. | Forces resin into the fracture network. Should alternate with vacuum, usually two or more cycles. |
| Leg check and flexing | For a star break, gentle pressure applied from inside the glass, or the cycle repeated, until the dark legs visibly gray out. | Legs are the last places to fill and the first places to fail. |
| Pit resin | A drop of thicker resin applied to the surface pit after the body fill is cured. | Restores the surface, seals against moisture, and is what makes the repair smooth. |
| Curing film | A small clear film or tab placed over the pit resin before UV cure. | Acrylic resin will not cure properly in contact with air. Skipping the film leaves a soft, tacky pit. |
| UV cure | A UV lamp held over the repair, or full daylight for longer. Body fill cured first, pit resin cured after. | Under-curing leaves resin that shrinks and yellows. |
| Razor levelling and polish | A fresh razor blade held nearly flat, scraping the cured pit resin flush, then a light polish. | Leaves the pit smooth and optically flat. This is the last step, and the most often rushed. |
Temperature runs through all of it. Glass that is too cold thickens the resin so it will not wick into the legs, and glass that is too hot thins it and can flash-cure the surface. The workable window and how techs manage it is covered in temperature and repair quality.
Phase three: after the repair
Inspect before you pay, and inspect outdoors. Fluorescent shop lighting hides exactly the defects you are looking for.
- Look at roughly 45 degrees in daylight. Straight-on light hides air. Angled light makes any remaining void flash bright silver.
- Check for dark or silver legs. Filled legs read faint gray. Any leg still reading dark or bright is unfilled, and that is where a future crack starts.
- Check for a resin ring on the glass surface. Excess resin cured onto the outside of the glass around the repair leaves a hazy halo or a raised edge. It should have been scraped off. A ring means the levelling step was rushed.
- Run a fingernail across the pit. It should glide across with no catch and no crater. A nail that drops into the pit means insufficient pit resin or an incomplete razor pass.
- Check the wiper path. A raised or rough pit in the wiper sweep will chatter and will wear the blade.
- Look from the driver's seat. Distortion matters more from where you actually sit than from outside the car.
- Confirm the invoice. Date, price, break type, repair location described in words, and the warranty terms. The location line is what makes a future warranty claim simple: see failed repairs and redos.
Set your expectations correctly before you judge. A good repair typically delivers substantial but incomplete visual improvement, and a faint outline is the normal result rather than a defect. What a repaired chip looks like shows where that line sits.
The 20-point scoring rubric
Score one point for each item you observed. This is a practical rubric built for this page, not an industry certification.
| Phase | Points available | Items |
|---|---|---|
| Before | 6 | Inspected from both sides; photographed; named the break type; checked edge distance; checked the inner ply; stated price and warranty in writing |
| During | 8 | Conditioned or dried the glass; shaded from direct sun; clean bridge seal; at least one full vacuum cycle; at least two vacuum-pressure alternations; pit resin applied; curing film used; razor levelled |
| After | 6 | No dark or silver legs; no resin ring on the glass; pit smooth to a fingernail; invited you to inspect before paying; warranty terms on the invoice; repair location written on the invoice |
| Score | Verdict | Action |
|---|---|---|
| 17 to 20 | Strong work by a shop with a real procedure | Pay, keep the invoice, note the shop for next time |
| 13 to 16 | Acceptable. Minor shortcuts, likely fine | Pay, but photograph the result today |
| 9 to 12 | Questionable. Elevated chance of later spread | Raise the specific gaps before paying and ask for the warranty in writing |
| Under 9 | Poor. Treat the repair as unreliable | Ask for a redo, or take the credit toward replacement and go elsewhere |
Red flags
- The five minute job. Setup, cycles, cure and finishing cannot be compressed below roughly 20 minutes for a single break.
- No vacuum step at all. Pressure-only injection traps air. If you never see a vacuum position used, the legs are not filled.
- Repairing what should be replaced. A long crack across the driver's view, damage at the glass edge, or a cracked inner ply. Read when replacement is required.
- Working in direct sun on hot glass with no shade and no comment about it.
- No curing film. The pit will stay tacky and pick up dirt.
- "It will be invisible." Overpromising the cosmetic result is the clearest sign of a sales pitch rather than a trade.
- Free repair with heavy pressure to file a claim or upgrade to a replacement you did not ask about. Legitimate insurer-paid repairs exist and are common, but the pressure tactic is worth recognizing: see free windshield offers explained.
- No paperwork. A verbal lifetime warranty with nothing written is not a warranty.
The same instincts apply when you are hiring for a full replacement, where the stakes are higher because the urethane bond is structural. The screening questions for that job are in choosing a shop, and the industry reference for both repair and replacement practice is the Auto Glass Safety Council.
Frequently asked questions
How long should a windshield chip repair take?
Plan on 20 to 40 minutes for one break, including setup, glass conditioning, the vacuum and pressure cycles, curing and pit finishing. Additional breaks add roughly 10 to 15 minutes each. Anything finished in under ten minutes skipped steps that matter.
What does a good repair look like afterward?
A faint gray shadow where the break was, no dark or silver legs, no bright ring, and a pit you cannot catch with a fingernail. Expect roughly 80 to 95 percent visual improvement as a rule of thumb, not a measured figure, and not invisibility. A visible outline is normal and is not a defect.
What is the vacuum cycle for?
It removes the air trapped inside the break so resin can occupy that space. Without it, air compresses into the ends of the legs and stays there. Those pockets are optical defects and stress concentrators, and they are where a later crack usually begins.
What should appear on the invoice?
The date, the price, the break type, the location on the glass described in words, and the warranty terms including what the shop credits toward a replacement if the repair spreads. Without the location noted, a warranty claim later becomes an argument.