How to Sand Metal to Remove Rust Prior to Painting

The most critical step in any painting project is the prep work.

Painting metal is no exception. One of the biggest threats to a proper paint job on metal is rust. When left exposed to the elements, metal will rust and create a substandard surface for paint. Luckily, rust can be easily removed, allowing you to paint over the metal and get a long-lasting finished look that you will love. Follow some simple steps for sanding to remove rust before painting metal.

Scrub your metal vigorously with a steel-bristled brush to begin attacking the largest rusted areas. This step requires a lot of elbow grease. Really apply pressure and try to remove as much rust as possible.

File flat areas with a coarse file continuing to attack the largest areas of rust.

Use sandpaper to work on the rounded sections. Sandpaper is pliable and will allow you to remove rust on round edges and in smaller crevices.

Spray phosphoric acid onto the surface of your metal. Phosphoric acid will react with the metal, creating an oxide coating on the surface. The acid will attach to spots your have missed or couldn't reach. Once dry, use a steel-bristled brush to remove this coating.

Thoroughly rinse your metal item with water to prevent the phosphoric acid from damaging the metal. Once all the rust is removed, move on to priming and painting your metal.

Things You Will Need

  • Steel-bristled brush
  • Coarse file
  • Sandpaper
  • Phosphoric acid


  • Phosphoric acid is not the only choice to chemically remove rust. Many products on the market, Rustoleum and Rust Doctor for example, make water-based products that also will remove rust.

About the Author

Lisa East Hunter is a consultant and freelance writer in Phoenix. Her background in marketing and technology led her to explore all avenues of writing. She is currently dividing her time between freelance writing and her consulting business. Hunter has a Bachelor of Science in management information systems and marketing.