Here in the Atlantic states we are constantly barraged with salt, whether in the air or on the roads. This, combined with moisture, can rust exposed metal with alarming rapidity. Many homeowners, seeking to maintain and restore their metal railings and fixtures, ask us, “Can I paint over rust?”
Yes, You can Paint over Rust
Using the right products and techniques, painting over rust is actually feasible. There are numerous kinds of paints available for this process, of which Rust-Oleum is the most famous. These paints can come both in spray and brushing forms.
How to Paint over Rust
The first step in dealing with exterior rust is to clean it as thoroughly as possible. In most cases, painting directly over rust without scraping it off is similar to filling a tooth without first drilling the cavity–the surface underneath will continue to corrode underneath the fine exterior. Use a wire brush to scrape away any loose rust or flaking paint, and use sandpaper to remove particulates and smooth out the surface. Next, wash the surface with a strong detergent. A clean surface is always the first key to a great paint job.
On most metal-painting projects, a spray paint will achieve a smoother finish and is more likely to match the surrounding paint. Try to match the level of gloss with care, so that the newly painted spot will match. For best results, repaint the whole surface for a crisp, even appearance. Before applying your paint, however, use a rust-blocking primer, unless your topcoat specifies that it does not need one.
For some situations, there are certain products available called rust converters that can be painted directly over unscraped rust. These products convert rusted metal back into a harmless deposit. While they cannot restore the original strength of the metal, these coatings can be effective and covering and preventing rust. This will also leave the rough texture of rust showing through the surface.