DESCRIPTION
The painted surface displays more or less small pimples.
CAUSES
Blistering is caused by moisture or contamination under the paint film due to:
- Moisture absorption by the underground (putty and sealer) before the application of the finishing coat.
- Moisture condensation on the substrate f.i. depending on a sudden change in temperature (e.g. the hot car out of the oven).
- Contamination of the substrate by water, grease, oils, a.s.o.
- Use of non compatible products (f.i. not suitable or contaminated thinners).
- The painted surface, before the complete through hardening of the film, was exposed to an high level of moisture or rain.
- Thinning of water-borne product with tap water (contains mineral salts).
REMEDY
After drying through of the film control the depth of the pimples:
- If these are between the final coat and the underground, sand to reach a completely smooth surface, then re-coat.
- If the pimples are between the substrate and the undercoat, sand thoroughly, clean accurately and repeat the complete paint system.
PREVENTION- Ensure the surface is thoroughly cleaned before any operation(use compressed air and silicon remover degreaser)
- Protect the surface before the paint application and immediately after, to avoid moisture condensation.
- Use experimented paint cycles to avoid any incompatibility.
- Control the compressed air supply to eliminate any trace of oil, fat or water.
- After wet sanding allow water to evaporate.
- Dry-sand only polyester putties.
Download the Defects Manual