Shrinkage
Cause
- Topcoating before undercoats have thoroughly dried/cured.
- Undercoats applied excessively wet with inadequate flash time between coats.
- Undercoats under reduced.
- Using a poor grade and/or too fast evaporating thinner/reducer for spray conditions.
- Finishing over body filler that has not thoroughly cured.
- Using too strong solvent cleaner or using thinner/reducer as a surface cleaner.
Repair
- Allow the affected area to thoroughly dry/cure, sand and refinish.
- If additional filling is necessary, apply a primer surfacer, sand smooth and refinish.
Prevention
- Allow undercoats to thoroughly dry/cure before sanding and/or topcoating.
- Thin or reduce undercoats according to product label directions. Apply in thin wet coats allowing adequate flash time between coats to avoid "bridging" scratches.
- Select recommended thinner/reducer based on temperature, humidity, air movement, and size of repair.
- Follow body filler manufacturer's recommended cure time.
- Use solvent cleaner designated for either lacquer soluble or cured enamel/urethane insoluble substrate.