How to Paint Rusty Steel

Loosen the rust with a wire brush. You can either do it by hand or use a wire wheel brush attachment inserted into a hand drill. If you must prepare a large rusty steel surface, use a sand blaster to remove the rust. A sandblaster uses compressed air and particles of sand to blow off the surface of the steel.

Sand the surface thoroughly with an 80-grit sandpaper, then with a finer 120-grit sandpaper. Sweep away your work area with a broom to avoid getting particles on the surface during the painting process.

Wash the surface with a degreasing cleaner. Pine, orange and other citrus-based cleaners will work well. Use a scrub brush to scrub the surface and rinse clean with water.

Wet a cloth with paint thinner and wipe it over the surface of the steel. It will remove the slight rusty finish that appears after cleaning steel.

Place the steel on a drop cloth or cover the area around the steel with drop cloths, to avoid getting paint on it.

Brush a rust-inhibiting primer that includes zinc chromate or iron oxide onto the metal. Allow the primer to dry according to package directions. Repeat, if recommended. Do not use a paint sprayer or spray paint cans for the rust inhibitor, because they will not reach into all the tiny pores on the steel's surface. This is more important than the top coat because it will slow down the oxidizing process in the future. You can also use an anti-rust enamel paint over 1 coat of regular primer.

Paint your steel surface with 2 coats of outdoor paint, since most steel is kept outside. You can choose a matte, semi-gloss or glossy finish, according to your preference. Use a brush or paint roller to apply the exterior paint, if you want to ensure you reach every crevice of the steel. Hold a brush at the base of the handle to ensure you have good control of your brush strokes. Use spray paint, if you want to ensure there is an even coat. Make sure you hold the can at the proper distance, as indicated by the directions on the can. Spray parallel to the object, moving your hand back and forth in smooth motions during application. This will provide a professional-looking finish and avoid drips on the steel surface.