Coating

Mottling / clouding

Lighter and darker patches in metallic or pearl paint — an effect of irregular "clouds" visible when viewed from different angles.

Thinner too fast — the paint dries too quickly and the metallic flakes have no time to settle parallel to the surface
Thinner unsuitable for the product — the wrong working viscosity disorients the flakes during application
Spray pressure too high — the metallic flakes are "fired" in different directions instead of lying flat
Wrong spray gun or a nozzle unsuitable for the base coat
Base coat applied too thickly — too much material at once does not allow the flakes to settle
Flash-off time between base coats too short
Poor overlap between spray passes — inconsistent amount of material on the surface
Incorrect spraying technique for drop coats — flash-off time too short, pressure too high or too many coats at once

Select the thinner according to the technical data sheet, taking into account booth temperature and air flow
Use the appropriate spray gun and the nozzle recommended for the base coat in question
Observe the recommended spray pressure — for metallic base coats usually lower than for clear coats
Apply the base coat in thin, even coats with correct overlaps
Observe the flash-off times between base coats
For drop coats, use the correct spraying technique in accordance with the technical data sheet

Establish the cause before starting the repair — check the thinner, pressure and spraying technique so that the error is not repeated
Sand the base coat dry with P600 or wet with P1000 — do not sand through to the primer
Before reapplying, carry out a trial on a test panel with the selected thinner and gun settings
Reapply the base coat using the correct thinner for the current temperature and air flow in the booth
Observe the recommended spray pressure and gun-to-panel distance
With metallic-effect colours, apply the final base coat as a so-called "drop coat" from a greater distance and at lower pressure — this orients the flakes parallel to the surface
Apply clear coat once the base coat has properly flashed off