TotalBoat Aluminum Boat Etch Wash is applied to bare aluminum, galvanized steel, and other non-ferrous metals to prepare the surface for application of some type of coating, such as paint or epoxy. The acid in Aluminum Boat Etch Wash can damage paint on surrounding surfaces if left on long enough, so for best results, avoid getting Etch Wash on painted surfaces, if at all possible. When applying Etch Wash, do not allow it to stay on the surface longer than five minutes and don't allow it to dry. Rinse it off completely with fresh water. If you have any concern about the acid in the etch wash damaging or removing paint on surrounding surfaces, test in a small, inconspicuous area.