A chip repair takes about a quarter of an hour, costs less than a tank of fuel and is over before most people have finished a coffee. Which is exactly why almost nobody knows what happened, and why two repairs that looked identical in the driveway can behave completely differently a year later.

The process itself is not secret and it is not complicated. It is six steps in a fixed order, and every one of them exists to solve a specific problem. Knowing what they are is the only reliable way to tell whether the person working on your car did the job or did most of it.

Step one: reading the damage

Before anything is touched, the technician establishes what kind of break it is and whether it is a candidate at all. That means checking the size against the resin system in use, checking the position against the driver's sightline, the glass edge and the camera bracket, and checking with a fingernail whether the inner layer of glass has been broken.

The part that gets skipped here is honesty. A technician who tells you upfront that a repair is borderline, might stay visible, or might not hold, is doing the harder version of the job. The easy version is to take the booking and let you discover it. If nobody sets expectations before starting, that is worth noticing.

Step two: cleaning the void without contaminating it

The damaged area gets cleaned and any loose glass fragments are removed from the impact point, usually with a fine carbide bur. On older damage this step matters enormously, because a void that has been open for months is holding dust, road film and whatever wax went over it during a wash.

What must not happen at this stage is water. Any moisture left inside the break will stop the resin bonding and will eventually go cloudy inside the finished repair. On a damp morning a technician will often warm the glass gently first to drive moisture out, and skipping that is one of the most common reasons a repair looks fine on the day and hazy a month later.

Step three: the bridge and the seal

An injector assembly is mounted over the break, usually held by suction, and sealed against the glass. This is the piece of equipment that makes everything afterwards possible, because it creates a closed chamber over the damage that can be taken to vacuum and then to pressure.

The seal has to be genuinely airtight. A leaking seal means the vacuum never pulls properly, which means the air never fully leaves the break, which means the resin cannot fully occupy it. Everything downstream depends on this being right, and it is invisible in the finished result.

Step four: vacuum, then pressure, then repeat

Here is the part that surprises people, because it is not one action but a cycle repeated several times.

The chamber is taken to vacuum first, which pulls the trapped air out of the break and out along every crack leg. Then resin is introduced and the chamber goes to pressure, driving the resin into the space the air just left. Then back to vacuum, which pulls out any air the resin trapped as it moved. Then back to pressure again. A good repair cycles this several times, and on a star break with long legs it can take a while, because resin travels slowly down a narrow leg.

This is where rushing shows up. A single vacuum and a single push looks the same to a customer standing beside the car. The difference is air left behind in the leg tips, which is both a weak point and a visible one.

Step five: curing under ultraviolet light

The resin is an acrylic that stays liquid until ultraviolet light triggers it to harden. A curing lamp goes over the repair for a set time, and a small curing strip is usually laid over the surface so the outermost layer sets flat rather than being inhibited by contact with air.

Two things go wrong here. Curing too briefly leaves resin soft under the surface, which fails later. Curing in direct sunlight is worse, because the sun starts hardening the resin before it has finished travelling into the break, which is why you will see technicians shading the glass or moving the vehicle. If someone repairs your windshield in full Phoenix sun with no shade at all, that is a real question worth asking.

Step six: scraping and polishing the pit

The last step is small and it is the one most often skipped entirely. Excess cured resin sitting proud of the glass is scraped flat with a blade, then a pit filler is applied to the impact point itself and cured, then that is levelled and polished.

Skip it and you get a repair that is structurally fine but feels rough under a fingertip and catches the light at an angle. It is also where wiper blades start to tear, because a raised lump of cured resin sitting in the wiper path will shred a blade over a few months.

What the finished repair should look like

Setting expectations correctly is part of the job, so here is the honest version:

  • The damage will be substantially less visible, not invisible. A faint mark usually remains and is easiest to see at an angle.
  • The strength of the glass in that area is restored, which is the actual point of the exercise.
  • The damage will not spread from that point again, which is what you paid for.
  • The surface should be smooth to the touch, with nothing catching a fingernail.
  • There should be no cloudiness or milkiness inside the repair, which indicates moisture or trapped air.

So can you do this yourself

A consumer kit contains a simplified version of the same idea, usually a suction bridge and a syringe. On fresh, clean, simple damage, used carefully by someone reading the instructions properly, it can produce a reasonable result.

What it cannot do is the multi cycle vacuum. Most kits generate suction by pulling a plunger and holding it, which is a fraction of the vacuum a professional unit reaches and cannot be cycled repeatedly with any consistency. On a bullseye that might be sufficient. On a star break with legs, the resin will not reach the ends, and the tips stay empty. And there is only one attempt, because cured resin cannot be removed and redone. A partial fill is now the permanent state of that windshield.

Six steps is the whole test

You do not need to know how to repair glass. You need to know that a proper repair has a preparation stage, a sealed chamber, a repeated vacuum and pressure cycle, a controlled cure out of direct sun, and a finishing pass on the pit. Anyone who runs all six is giving you a repair that holds. Anyone who mounts a bridge, squeezes resin in, shines a light at it and calls it finished has given you something that looks the same today.

If there is fresh damage in your glass, the clock on it is shorter than most people think, because the void is collecting contamination from the moment it appears. Our chip and crack repair service runs the full sequence at your home or workplace, and if the damage has already gone past the point where resin will hold, we will tell you that rather than taking the money for a repair that was never going to work.