How-To

Removing Stains in Concrete

Small stains in concrete countertops and walls can be removed using this simple technique from Fu-Tung Cheng's book, Concrete at Home.

By Fu-Tung Cheng

Concrete is vulnerable to stains from such things as lemon juice, wine, or vinegar no matter what sort of sealer or wax you apply to it. These and other acidic liquids can eat into the fines on the surface and roughen it slightly. Of course, one person’s annoying stains are, to another, a lovely patina that reveals years of use. It’s possible to remove individual stains without the need to refinish the entire piece. Below is a step-by-step guide. We recommend passing it on to clients, so they can handle those pesky little stains and abrasions: A stain like may look permanent, but it’s not.

The gear you’ll need: 800-, 1200-, 1500-, and perhaps 3000-grit diamond pads, sealer, and wax.

Wet the surface of the concrete and start with the 1200- or 1500-grit pad. (There’s no need to remove any wax, as the diamond pad will cut through it.)

Polish with a 1200-grit pad until the water gets cloudy. Sponge it off to see how the stain looks. If stain is removed, dry, reseal, and wax.

If the stain is still there, try the 800-grit pad. Work aggressively on the stain, and gradually work out in larger circles. Wipe it clean and check often. There’s a danger that grinding too aggressively with the 800-grit pad could expose some of the fines, which will change the look of the surface slightly.

After the 800-grit pad, left, go over the stain again with the 1200-, 1500-, or 3000-grit pad (the latter will give the surface a shine). Let the surface dry, apply a penetrating sealer, then wax.

Fu-Tung Cheng is principal of his Berkeley, California firm Cheng Designs and author of the bestselling book Concrete Countertops. Photos by: Matthew Millman

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edjeremy | Sep 30, 2019 10:27pm | #1
Concrete is such a versatile material. That would be a pretty gnarly stain if you have to go down to 800 grit. Thanks for the article. https://www.rentonconcretepros.com/concrete-stamping--staining.html