Stone chips: why they get fixed now rather than in spring

A chip the size of a match head looks trivial and stays that way exactly until moisture and salt reach it. After that it is no longer cosmetic.

What happens under the paint

1. The chip exposes metal — lacquer, colour, and primer are all breached.
2. Moisture and salt settle on the metal.
3. Rust starts at the point and spreads sideways under the paint, where it cannot be seen.
4. The paint blisters — there is a bubble underneath already.
5. Perforation — a welding repair.

The key point: stage 3 takes months and stage 4 a year or two. So you have plenty of time, which is exactly why nothing gets done.

Where they appear

The leading edge of the bonnet — the main zone.

Bumper and headlights — stones from the wheels.

Sills and arches — blasting.

Door edges — contact with other cars and objects.

Roof and pillars — rarer, and noticed later.

What to do yourself

For a small chip with no rust it is fifteen minutes:

1. Degrease — with alcohol or a dedicated product.
2. If there is a rust spot, clean it back to bare metal. The most important step: paint over rust stops nothing.
3. Rust converter — if it cannot be fully removed.
4. Primer in a thin layer, into the point itself.
5. Paint by code — the body colour code is on the vehicle plate; apply as a drop, not a smear.
6. Lacquer on top once dry.

The main mistake: painting straight over a rust spot. That is cosmetics for two months.

The second mistake: picking “a similar colour”. The paint code is on the plate — use it.

When not to do it yourself

Blistering paint — there is a bubble underneath, and touching in is pointless: it needs taking back to bare metal.

A patch larger than a coin.

Perforation — that is welding.

A chip on an edge where corrosion follows the seam — a bodywork repair.

The stages are covered in the underbody rust article.

Prevention

Protective film on the front — bonnet, bumper, mirrors, the area behind the arches. The most effective measure, and it works exactly where chips appear.

Keep your distance behind lorries — half of all chips come from there.

Never wipe a dry car with a cloth — grit on the paint works as an abrasive.

Go over the bodywork in autumn and touch in everything from the season — before the salted winter; covered in the road salt article.

In short

• A chip is exposed metal; after that it is only a question of time.
• Rust spreads sideways under the paint, so the visible spot understates it.
• Paint over a rust spot stops nothing.
• Take the colour from the body code, not “something similar”.
• Protective film works exactly where the chips happen.

Download the app — codes across every system are read with an ELM327 adapter over Bluetooth SPP on Android.