How to Repair Car Paint Scratches: Filler and Primer Guide

Assess the scratch before choosing a repair method

Car paint scratches range from light marks in the clearcoat to damage that reaches the primer or bare metal. Start by washing and drying the area, then inspect it under good lighting. A scratch that has not reached the colour coat may only need careful polishing. If the damage reaches primer, metal or plastic, it needs a proper refinishing repair.

Clean and prepare the damaged area

Remove dirt, wax, silicone and road film before sanding. Use a suitable panel wipe with clean lint-free cloths, then mask the surrounding area. Good preparation helps avoid adhesion problems and paint defects later in the process.

For more preparation detail, read our car panel preparation guide.

Sand only as far as the repair needs

Feather the damaged edges with an abrasive suitable for the substrate and repair stage. Avoid creating a large bare area around a small scratch. The aim is to remove loose or damaged paint and create a smooth transition for the next layer. Keep sanding dust under control and inspect regularly so the surrounding factory finish is not unnecessarily thinned.

Deal with bare metal and plastic correctly

When a scratch reaches bare metal, remove any corrosion and apply a compatible primer system before filler or paint. Plastic parts need products designed for automotive plastic and, where required, an adhesion promoter. Always follow the product technical data sheet for surface preparation, mixing, flash times and sanding guidance.

Our epoxy primer guide explains when epoxy can be a useful corrosion-resistant foundation.

Use filler only for genuine lows

A deep groove or low area may need a thin application of suitable body filler after the correct substrate preparation. Do not use filler simply to cover an unsanded paint edge. Shape it carefully, keeping the repair as small as practical, then use guide coat and a sanding block to identify remaining lows.

See our guides on choosing body filler and using guide coat for reliable preparation checks.

Prime the repair before colour

After the repair is flat and clean, apply the appropriate primer to isolate the repair and provide a sandable, stable surface. High-build primer is commonly used to refine small filler repairs; other primer types may be needed for bare metal, plastic or specific paint systems. Allow the correct curing and flash times, then block sand to the grit specified for the basecoat system.

Use our automotive primer guide to choose the right primer stage.

Inspect before applying colour and clearcoat

Check the panel under good lighting before basecoat. It should be smooth, clean and uniformly sanded, with no pinholes, sharp edges or deep sanding marks. Follow the coating manufacturer instructions for basecoat application, blend technique and clearcoat. Contamination control matters throughout: clean cloths, filtered air and correct panel cleaning reduce the risk of fisheyes.

Read our fisheye prevention guide and clearcoat guide before the final painting stages.

Find compatible repair products

Shadotech supplies automotive refinishing materials for surface preparation, priming and finishing. Browse the U-POL range and use product-specific technical data sheets for each repair.