Enviro-Terra™ RustCrete is a true breakthrough cleaner. With a pH of less than 1, this concrete rust remover has the performance of an acid, yet is safer and mild to skin like a liquid dish soap. Removes rust stains from concrete to restore the surface to like-new. The thickened formulation enhances dwell time and performance, and works on new and old, light and heavy, stains. Also effective on rust stains on other surfaces, including metal, porcelain, fiberglass and brick. Nonflammable and biodegradable. Ships DOT non-hazardous.