How to repair a car scratch yourself, and when to stop

You can fix a light scratch in the clear coat at home with a polishing compound and a bit of patience. You can hide a stone chip with a touch-up pen. Anything through to the colour or primer needs a proper repaint, and trying to fix it yourself usually turns a small job into a bigger one. Here's how to tell which you've got and how to do the easy ones properly.

First, the fingernail test

Run a fingernail across the scratch.

• Doesn't catch: it's in the clear coat. You can polish it.
• Catches slightly, scratch looks white or lighter: through the clear into the colour. Needs paint.
• Catches, and you can see grey or silver: down to primer or metal. Needs paint, and soon, before it rusts.

Our scratch guide has more on the layers.

Fixing a clear-coat scratch at home

What you need: car shampoo, a clean microfibre cloth, a cutting or polishing compound from an auto shop, and a second clean cloth.

1. Wash the area well. Grit under your cloth makes new scratches.
2. Put a small amount of compound on the cloth.
3. Rub along the scratch (not in circles) with firm, even pressure for 30 seconds or so.
4. Wipe clean and check in daylight. Repeat two or three times if it's improving.
5. Stop if it's not improving after a few rounds. You're taking off clear coat each time, and there's only so much.
6. Wax the area afterwards to protect it.

A machine polisher does this faster and better, but in the wrong hands it burns through the clear. If you don't own one, hand polishing is safer.

Touch-up pens for chips

A touch-up pen in your paint code (on the sticker in the door jamb) is fine for stone chips and tiny scratches down to metal, because the job is to seal the metal, not to look perfect.

1. Clean the chip with wax and grease remover or isopropyl alcohol.
2. If there's rust, pick it out with a pin and dab on rust converter.
3. Apply the paint in thin layers with the tip of a toothpick or fine brush, not the pen's brush, letting each dry.
4. Build it up level with the surrounding paint, then stop.

Don't try to run a pen along a long scratch. It will look worse than the scratch.

Things that make it worse

• Rubbing with a kitchen scourer, toothpaste or a "scratch remover" cloth from a servo. These are abrasives with no control.
• Spray cans of colour. The colour won't match, the edges will show, and a panel shop has to sand it all off before fixing it properly.
• Clear coat in a can over a colour scratch. Traps the problem under a layer of mess.
• Polishing a scratch that's through the colour. You'll thin the clear around it and achieve nothing.

When to bring it in

Anything that catches a fingernail. A scratch across more than one panel. Scratches on a plastic bumper corner (the paint's thinner there and they almost always go through). A keyed car. Anything on a car you're about to sell or hand back on a lease.

A localised repaint and blend makes a scratch disappear, and it's often a smaller job than people expect. Send a photo through the quote form and we'll tell you honestly whether it's a polish, a touch-up or a paint job. More on the spray painting page.