Visible lines in the paint film that follow sanding marks caused by the swelling action of topcoat solvents.
Causes
- Sanding with too coarse grit sandpaper
- Insufficient dry time of under coats before topcoating
- Too fast of solvent in surfacer causing film to "bridge" over
- Refinishing over soft or soluble substrates
Prevention
- Use appropriate grit sandpaper
- Allow undercoats to cure thoroughly before topcoating
- Apply a sealer over the primer surfacer
- Use appropriate reducer in the primer surfacer for the spray conditions
Correcting
- Sand and refinish the area, using a sealer before topcoating
