Permatex Rust Treatment destroys old rust and prevents new rust in one step. Just brush or spray on and within minutes rust is replaced by a durable black polymer coating, which can be painted and serves as an excellent protective primer. Specially formulated to be used with body filler and fiberglass, this rust treatment can be used in temperatures between 50°F and 90°F (10°C and 32°C) and on surfaces which do not exceed 200°F (93°C). Destroys rust on all automotive applications, trucks, trailers, storage tanks pipes, valves, fences, bulkheads, overheads, decks, hatch covers (topcoat with appropriate marine paint), agricultural equipment, plows, tractors, and snow removal equipment. Not recommended for automotive exterior sheet metal repairs.