How to Prevent Fisheyes in Car Paint Repairs

What fisheyes are in automotive paint

Fisheyes are small circular craters that appear when fresh paint or clearcoat pulls away from localised contamination on the surface. They can ruin an otherwise sound repair because the coating does not wet the panel evenly. The right response is to identify the contamination source, prepare the panel again and follow the coating system instructions.

Typical causes of fisheyes

Silicone, wax, polish residue, oils, grease, moisture and airborne contaminants can all interfere with paint adhesion. Contamination can come from a vehicle surface, cleaning cloths, compressed-air lines, spray-gun equipment, hands or products used nearby. A panel may look clean while still carrying residues that become visible only after coating.

• Wax or silicone left on the panel.
• Incorrect cleaning method or dirty cloths.
• Oil or moisture in the airline.
• Polish, aerosol or workshop contamination.
• Touching prepared surfaces with bare hands.

Clean in the correct order

Use a suitable panel wipe before sanding where required and again after sanding, following the manufacturer instructions. Use one clean cloth to apply the cleaner and a second clean cloth to remove it before it dries. Reusing saturated cloths can move contamination rather than remove it. Avoid household cleaners, which may contain ingredients unsuitable for refinishing.

Prepare the repair area thoroughly

Remove unstable coatings, corrosion and old repair defects before starting the paint stages. Sand to the grit range recommended by the product data sheet, blow off dust with clean dry air, then clean and tack-rag just before spraying. Our car panel preparation guide covers the wider preparation workflow.

Keep compressed air clean and dry

Airline contamination is an easy cause to miss. Drain compressors as part of workshop routine and use properly maintained filtration and water separation appropriate to the equipment. Inspect hoses, couplings and gun connections for oil or moisture. Do not point an unfiltered airline at a prepared panel.

Control the spray area

Keep silicone-containing dressings, aerosols, lubricants and polish work away from the refinishing area. Use clean overalls and gloves, and keep masking paper, benches and mixing areas tidy. Dust control does not replace contamination control, but a clean workspace makes it easier to prevent both types of defect.

Mix and apply products as specified

Use only the correct hardener, reducer and ratio stated for the chosen product. Do not add extra materials in an attempt to fix a contamination problem unless the coating manufacturer specifically directs it. Correct film build, flash time and gun setup reduce the chance of creating separate application defects.

For the clearcoat stage, see our automotive clearcoat guide.

What to do if fisheyes appear

Stop and assess the repair before adding more material. Once the coating has cured sufficiently, follow the manufacturer guidance for sanding, cleaning and reapplying the affected area. Simply applying another coat over active contamination often repeats the defect. Our car paint defects guide explains related paint issues and prevention.

Use compatible refinishing materials

Shadotech supplies automotive refinishing materials for preparation, priming and paintwork. Browse the U-POL product range and follow each product technical data sheet for safe, compatible use.