Cause
- Using too much or too little hardener in the putty/filler.
- Insufficient mixing of putty/filler components.
- Applying a surfacer, sealer and/or topcoat before putty/filler has thoroughly cured.
- Applying undercoats and/or topcoats excessively wet.
- Clearcoating a white or light color without using a stain-free body filler.
Repair
- Allow topcoat to thoroughly cure.
- Sand affected area, isolate with two component undercoats and refinish.
Prevention
- Use correct amount of body filler hardener.
- Mix components thoroughly.
- Allow putty/filler to cure thoroughly before topcoating.
- Apply undercoats and/or topcoats in medium-wet to wet coats; always allowing proper flash time between coats.
- Use non-staining body filler, especially when clearcoating light colors.
- Isolate suspected staining filler by applying a two-component surfacer and sealer.* Allow to cure, following product recommendations, then apply desired topcoat.
*Two component acrylic urethane primer surfacer and acrylic urethane sealer may be used to top a majority of body filler staining problems. Both are required and must be allowed to fully cure for maximum stain resistance. However, for 100% assurance against body filler staining, use a non-staining body filler according to manufacturer's recommendations.