PC-Rustproof® RC is a synthetic polymeric formula that converts existing rust into a moisture-free, black protective coating for metal surface preparation. When applied to rusted metal, it chemically converts rust into iron phosphate. Not only does it eliminate existing rust, but also it seals out moisture to prevent the possibility of future rust formation and corrosion. This easy-to-use product is the first step in providing long-term protection of steel and iron surfaces.