Aluma Protect 4400/4401 is a 2 part strontium chromate primer designed to form the ideal barrier coat over roughed bare aluminum. This is the appropriate epoxy to use when aluminum has been sandblasted, sanded or ground so that a tooth is present. For smooth aluminum, choose Pettit Metal Primer 6455/044. AlumaProtect provides maximum resistance to fresh or salt water, thus eliminating corrosion. This complete coating system resists water, industrial chemical fumes, and very humid environments. Intended to be used as a primary coat over bare aluminum hulls and outdrives. AlumaProtect 4400,4401 will chalk if not topcoated. Two coats are recommended over sandblasted aluminum. Then overcoat with Pettit Protect 4700/4701 for optimum results before finishing antifouling paint. Easy to Mix and Apply