Advice on paint defects

Solvent Boil

Definition

Blister-like surface defects due to solvent entrapment in the surface of the paint film.

Cross-section through a paint-film with Solvent-Boil, 200 x magnification Solvent-Boil in Clear Lacquer coat, 100 x magnification Solvent-Boil visible on a paint surface Solvent popping at face view Thin section of solvent popping Target cross section of solvent popping

Causes

  1. Coats applied too thick. 
  2. Hardener and/or Thinner too fast. 
  3. Flash-off time between individual paint coats too short. 
  4. Flash-off time before baking or Infra-red drying too long. 
  5. Insufficient distance between IR lamps and object causing too high a temperature. 
  6. When using a wet-on-wet system, too short a flash off between coats.

How to avoid

  1. Keep to recommended film builds.
  2. Use correct choice of hardener and thinner for the working temperature available (see temperature table).
  3. Keep to recommended flash-off times.  
  4. When using Glasurit products, no flash-off time is required before baking. 
  5. Keep to recommended distances and intensities when drying with Infra-red. 
  6. Keep to recommended film builds and flash off times between coats.

Repair

For surface defects caused by solvent boiling, the paint coats must be sanded back to a sound substrate. Refinish using the correct choice of primers and top-coats. If the bubbles are not completely removed, pin-holes will appear when the next coats are applied (see chapter on "Pinholes").