Undercoat removal made easy! Here's the solution for undercoats that can be imprinted with a thumbnail. Biodegradable undercoat remover quickly loosens the bond of the undercoating to the base metal and allows you to easily scrape it loose. Use PRE Painting Prep to remove any remaining residue for a in.paint readyin. surface. Not for use on baked-on, epoxy or urethane undercoatings. For cleaning up an area to be welded, this is a must! 17 oz. net wt. aerosol.