RX-90 Red oxide Anti rust primer spray is for use on clean bare metal or lightly rusted metal. RX-90 can be over coated on most popular paints. RX-90 red oxide anti rust primer spray is tough and durable for commercial and industrial settings. To obtain the best anti-rust performance the surfaces are to be primed must be in sound condition, clean, and free from oil or grease. If the surface has been previously painted, remove all loose or flaky paint with a wire brush to obtain a smooth clean surface. RX-90 is a fast drying formula.