How to Fix Mottling Paint Defects in Metallic Paints

also known as: clouding, shadowing, flooding, muffling, floating, misting, chalking, precipitation, blooming, bloom, bleaching

Contents

1 Description
2 Causes
3 Prevention
4 Solution

Description

Mottling in paint or mottling paint defects occurs in metallics when the flakes float together to form striped (or spotty) appearance

Causes

Basecoat flash-off time too short before application of clearcoat
Basecoat applied too wet (Coat affected by humid air or cold weather)
Wrong application: Holding spray gun too close to work or uneven spray pattern
Wrong preparation: wrong thinner or material not uniformly mixed

Prevention

Apply basecoat evenly and keep to recommended flash-off times
Do not spray the metallic basecoat too wet
Select thinner suitable for shop conditions (e.g. faster-dry solvent in cold weather)
Agitate/stir pigmented topcoats, incl. metallics, thoroughly
Adjust spray gun properly, incl. air pressure. Use proper spraying techniques

Solution

If mottling occurs during the application of basecoat: compensate by spraying a thin layer of basecoat over the affected area.
If mottling occurs after the application of clearcoat: allow to dry, sand it and reapply basecoat and clearcoat.