Adhesion loss can occur in two different ways. Firstly there can be adhesion problems to the substrate (total paint structure) and secondly there can be an inadequate bond between the individual coats (Intercoat Adhesion).
CAUSES Adhesion loss can occur if:
1. Substances which cause adhesion problems are left on the substrate to be coated (e.g. Silicone, oil, fat, wax, rust, polishing residue, etc).
2. An incorrect primer was applied to the substrate.
3. Sanding of the substrate was inadequate or not carried out at all.
4. The primer or base-coat was too dry or too thinly applied.
5. Drying time between final coat of Base-Coat and top clear coat is too long.
PREVENTION To avoid adhesion loss occurring, the correct primer should be used for problem substrates (e.g. Aluminum and plastics), the primer should be applied in sufficient film build and the manufacturers instructions should be followed. Apply wet spray coats, avoid applying basecoat too dry.
REPAIR Remove the coats with poor adhesion by sanding and re-coating.