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Loss of adhesion

Definition

Loss of adhesion can present itself in two different ways: there can either be a lack of adhesion between the substrate and the whole paint system or a lack of inter-coat adhesion (between the individual coats).

HAFTUNGSVERLUST

Causes

Loss of adhesion can occur when:

  1. Substances that can cause adhesion failure were left on the substrate when it was painted (for example, silicone, oil, grease, wax, rust, sanding residue, etc.)
  2. An unsuitable primer was applied to the substrate
  3. The substrate was sanded insufficiently or not at all
  4. Undercoat or basecoat was applied too dry or too thin
  5. Drying conditions were not taken into account
Haftungsverlust
10 x magnification
Haftungsverlust
Reverse side of a flake of paint removed from a fine sanded Aluminium substrate (with oxide residue adhering). 50 x magnification
Haftungsverlust
Reverse side of a flake of paint removed from a coarse sanded bodywork surface (with metal and rust residue adhering). 50 x magnification

HOW TO AVOID

To avoid loss of adhesion, always use the suitable primer for the respective substrate (for example, for aluminium or plastic). Apply undercoat materials as specified (in the technical data sheets). Do not apply excessive film builds. Thoroughly clean the substrate before painting.

REPAIR

Remove all coats with poor adhesion. Thoroughly sand and clean the substrate. Repaint using the recommended undercoats and/or topcoats.