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Solvent boils/popping

Definition

Blister-like surface defects due to solvents trapped in the paint film.

Kocher

Causes

  1. Excessive film build
  2. Hardener and/or reducer too fast
  3. Flash-off time between spraycoats too short
  4. Flash-off time before baking or infra-red drying too long
  5. The panel temperature becomes too high when the distance between IR lamps and painted object is too small
  6. Flash-off time between spraycoats too short for wet-on-wet process
Kocher
Cross-section through a paint-film with Solvent-Boil, 200 x magnification
Kocher
Solvent-Boil in Clear Lacquer coat, 100 x magnification
Kocher
Solvent-Boil visible on a paint surface

HOW TO AVOID

  1. Keep to recommended film builds.
  2. Use hardener and reducer suitable for the ambient temperature (see temperature table).
  3. Keep to recommended intermediate 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 infrared.
  6. Keep to recommended film builds and flash-off times between coats.

REPAIR

For surface defects caused by solvent boils, sand the paint system down to a “sound” substrate. Refinish using the recommended undercoats and/or topcoats. If solvent boils are not completely removed by sanding, pinholes will appear once the next coats have been applied (see entry on “Pinholing”).

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