How to Remove Rust Marks From Concrete

A paste mixture can remove rust stains from concrete.

After your metal table and chairs have been sitting on your concrete patio for months, you discover ugly rust stains left behind by the feet. You might find rust stains on other concrete surfaces around your home -- sidewalks, foundations, floors and walls. The Michigan State University Extension recommends a simple formula for making rust stains disappear from concrete.

Things You'll Need

• Stiff-bristled brush
• Sodium citrate crystals
• Calcium carbonate (whiting) or fuller's earth
• Putty knife

Instructions

1. Scrub any excess rust off the concrete surface with a stiff-bristled brush.

2. Combine 1/2 cup of sodium citrate crystals with 3 cups of water. Add just enough calcium carbonate powder, also known as whiting, or fuller's earth powder to give the mixture a paste-like consistency. Fuller's earth is a highly absorbent clay material.

3. Apply the paste to the rust stains on your concrete, using a putty knife. Spread the paste around to cover the spots.

4. Allow the paste to dry, then scrape it off with your putty knife. Repeat the process if you can still see the rust stains. When the stain is gone, scrub the surface with warm, soapy water, then rinse.

Tips & Warnings

• Whiting can be purchased at art-supply stores.

• For walls, Cement Concrete and Aggregates Australia recommends a 50-50 mixture of sodium citrate and glycerin to form a very thick paste that will stick to the vertical surface. Leave it for two or three days, then scrub it off. Repeat if necessary.

• The Concrete Network recommends removing rust with cleaning products containing oxalic acid.

• Be careful when trying to remove rust stains on decorative stamped concrete. Apply the paste to a small test area first.

References

• Michigan State University Extension: Concrete, Cement -- Rust Stains
• Cement Concrete and Aggregates Australia: Removing Stains From Concrete
• The Concrete Network: Chemicals Help Clean Specific Stains