Rust forms on the surface of metals when it is exposed to moisture and air, a process also known as oxidation. If any part of your vehicle is exposed to excess salt and rain, the area will eventually begin to corrode and rust. If the area is left untreated, the corrosion will spread throughout the metal and eventually destroy the body and frame of the vehicle. Repairing the damage as soon as you notice it will prevent future corrosion.
Sand the rust-damaged areas with 600-grit sandpaper. If the damaged area is too large to sand, use an angle grinder to grind away the rust, paint, and primer on your vehicle. Use a wire brush cup on the grinder and hold the grinder in your hand, while allowing it to spin onto the surface. Remove all of the rust until you only show the bare metal. If the rust has penetrated throughout the metal and created holes, you will need to consider purchase a new panel or replace the damaged metal.
Apply a rust converter to the area and let it dry. The chemicals in the rust converter will change the chemical composition of the rust and stop any future damage. Let the rust converter dry completely. Any remaining rust will turn black and will be ready for removal.
Soak a piece of 800-grit sandpaper in water and then sand the area. Wet sanding ensures a smoother finish by eliminating excess dust that would normally accumulate while sanding. Smooth out any remaining imperfections in the metal.
Wet sand the area until the entire area is as smooth as the surrounding areas with 1,200-grit sandpaper
Spray the area with self-etching primer. The self-etching primer will protect the metal from any future damage, and seal it, by forming a moisture barrier.
Prepare the area by applying regular paint primer. Allow the primer to completely dry before painting the area with an automotive paint. Follow the manufacturer's instructions on priming and painting your vehicle.
