Things You'll Need
A fresh coat of paint will give a rusty metal surface a whole new look. In addition to correcting surface imperfections resulting from the rust, paint creates a surface barrier that halts the oxidation process, barring additional rust from forming. To prevent bubbling, flaking and pitting over time, you should take particular care in preparing your rusty metal surface for painting. A well-prepared paint job will preclude these problems and protect your metal surface for years to come.
Scrape off any flaking rust or oxidation with a steel-bristle brush.
Sand the metal thoroughly with 80-grit sandpaper. Follow the 80-grit sandpaper with a lighter 160-grit paper.
Rinse the metal with clean water to remove any rust particles. Allow the surface to dry thoroughly.
Fill any dents or rust holes in the surface with a high-quality metal-filling compound, following the manufacturer's instructions. Allow the compound to dry thoroughly and sand the patched area with 160-grit sandpaper until it is blended smoothly into the surface.
Clean the entire surface of the metal with a light layer of paint thinner applied to a clean rag.
Apply two coats of water-based metal primer to the surface, using a medium-bristle brush. Allow the surface to dry thoroughly, at least 24 hours, before painting.
Paint thinner is highly flammable -- always dispose of paint-thinner soaked rags in an approved receptacle according to the manufacturer's instructions to avoid accidental combustion.