Car Scratch Repair: When to Polish, Touch Up or Repaint

A scratch can be polished when it sits within the clearcoat and there is enough clear left to remove a thin layer safely. Polishing levels the surface around the scratch so light no longer catches its edges.

Swirls, light wash marks, fine key marks that have not broken through and many marks from car parks fall into this group. A paint-depth gauge helps the technician decide how much can be removed safely. Some scratches can be greatly reduced rather than fully removed, and a good detailer will tell you that honestly before starting.

A simple guide is the fingernail test. If your nail slides over the scratch, polishing may well work. If it catches, the scratch is probably into the colour coat.

Touch-up paint is suitable for small, narrow damage such as stone chips and short deep nicks, where a full refinish would be out of proportion. A professional touch-up fills the damage in thin layers of matched colour and clear, then levels and polishes it flush.

It is not the same as dabbing on paint from a bottle. Even done well, a touch-up is usually less visible rather than invisible, especially on metallic colours. Long scratches rarely look good with touch-up alone. Our stone-chip repair guide goes into more detail.

A panel needs refinishing when the scratch is long, wide or through the colour coat over an area that touch-up cannot hide. Key scratches along a door, scrapes from a pillar in a car park and scratches with cracked paint around them usually fall here.

• The scratch has exposed primer, metal or plastic over a visible length.
• There are several deep scratches on the same panel.
• The paint around the scratch is cracked, lifting or flaking.
• Previous DIY repairs have left a rough or mismatched patch.

The repair is matched to the existing colour and, on many colours, blended into the neighbouring panel. Our guides to paint colour matching and panel repaints versus resprays explain the next steps.

Exposed steel should be repaired quickly because it can begin to corrode, and corrosion can spread under the surrounding paint. A scratch that needed a small repair can then need sanding back and refinishing over a larger area.

Aluminium and plastic panels do not rust in the same way, but bare aluminium can still corrode and plastic left exposed is harder to prepare properly later. Our article on common paint defects shows how small damage grows if it is left.

Some scratches can be repaired locally, within a small area of the panel, rather than repainting the whole panel. This works best on bumpers, lower areas and colours that blend well.

The technician prepares and repaints the damaged zone, then blends the new colour and clear into the surrounding original paint. Where the scratch sits in the middle of a large, flat panel, or the colour is a difficult pearl or tri-coat, refinishing the full panel is often the more reliable result. Matte and satin paint has its own rules, covered in our matte paint repair guide.

No. Polishing only works when the scratch stays within the clearcoat and enough clear remains to remove safely. Deeper scratches need new paint, although polishing can still make them less visible.

A grey, white or dull layer showing at the bottom of the scratch often means primer is exposed, and silver usually means bare metal. Lighting can be deceptive, so a professional inspection is the safest way to be sure.

Usually not completely. A professional touch-up that is filled, levelled and polished can be hard to see from normal distance, but metallic colours in particular may still show up close. It is best for small chips and nicks.

Yes, if they expose bare steel. Corrosion can start in the scratch and spread under the paint around it, so scratches through to metal should be repaired promptly.

Be careful. Abrasive compounds and sandpaper can thin or haze the clearcoat and turn a small repair into a panel refinish. It is safer to have the depth assessed first.

No. Ceramic coating adds gloss and makes washing easier, which can reduce wash marks, but it is far too thin to stop real scratches. PPF is the product designed to absorb scratches and chips.