Scratch Removal and Paint Correction: What Polishing Can Do

Understanding the layers

Car paint is made up of primer, colour and a clear lacquer on top. Most light scratches only affect the clear coat, which is the outermost layer. Deeper scratches go through the lacquer and into the colour or even the primer and metal.

Polishing works by removing an extremely thin amount of lacquer to level the surface around a scratch so that the light no longer catches it. That means there is only so much to give: the lacquer is thin, and a repairer has to be careful not to take too much.

The fingernail test

Drag a fingernail lightly across the scratch. If it glides over without catching, the damage is probably within the clear coat and may polish out. If your nail catches in the groove, the scratch is likely deeper and polishing alone will reduce it rather than remove it.

It is a rough guide, not a certainty. Dirt in the scratch, the angle of the light and the colour of the car can all trick you, so a repairer will look at the damage closely before giving an opinion.

• Nail glides over: probably clear-coat only
• Nail catches slightly: may improve, may not disappear
• Nail catches firmly: likely through the lacquer
• White or grey showing: probably to primer or bare metal

Swirl marks and fine hazing

Swirl marks are the fine circular scratches that show in bright sunlight, usually caused by dirty wash mitts, automatic brush washes or dry wiping. They give the paint a dull, spidery look, particularly on dark colours.

Machine polishing is the standard way to deal with them. A trained technician uses a polishing machine with suitable pads and compounds, working in stages from a more cutting grade to a fine finishing polish. Done carefully, it can bring back depth and shine.

Darker colours show swirls the most, while light silvers and whites hide them. That is one reason owners of black and dark blue cars tend to notice them first, and why the improvement after correction can look so dramatic.

What paint correction involves

The car is washed and inspected, and the paint is assessed so the right products and pads are used. Areas are then polished in sections, and the surface is checked under strong light as the work progresses. Some defects improve a lot, others only partly.

Not every mark will disappear, and a good technician will tell you so. At Banks of the Tyne in Hebburn, paint correction is part of our paintwork service, and we would rather set honest expectations at the start than promise a finish the paint cannot give.

Expect the car to be assessed before any quote is given, because the amount of work depends on the number of defects, the size of the car and the hardness of the paint, which varies between manufacturers.

When polishing is not enough

If a scratch has gone through the colour layer, polishing will not fill it. Such damage generally needs a repair: a localised paint repair such as a SMART repair, or a respray of the panel if the damage is more extensive.

Thin paint is another limit. On older cars or repainted panels, there may not be enough lacquer left to polish safely, and a repairer may advise against it to avoid cutting through.

If a scratch is on a panel that has been repainted before, tell the repairer. Aftermarket paint can behave differently from factory finish when it is machined, and knowing the history helps avoid surprises.

Looking after the finish

Wash with clean mitts and plenty of water, use separate buckets for washing and rinsing, and dry with a soft clean towel. Avoid brushing dirty paint or wiping dust off dry. Regular washing in winter removes salt and grit before they do harm.

A wax or sealant helps protect the surface between polishes, but it will not stop scratches caused by poor washing.

Frequently asked questions