Stains on concrete can ruin your home’s curb appeal, so cleaning these unsightly eyesores should be a top priority for homeowners. The porous concrete surface of your driveway absorbs many unwanted substances which can leave behind stains, but a few particular materials are more difficult to remove than others. This guide helps homeowners remove three of the most common and unsightly stains – oil and grease, paint and rust.
Removing Oil and Grease
If the oil or grease stain is small and fresh, try mixing household dish detergent with water, pouring it over the stain and scrubbing with a wire brush. This may be the only cleaning agent needed. If the stain is large and sunk into the concrete, try this more comprehensive method: Mix one ounce of trisodium phosphate (TSP) with one cup of water and add enough absorbent material, such as cat litter or baby powder, to the fluids so the mixture turns paste-like. (Be sure to wear gloves and a mask when handling TSP to protect your skin and lungs from this useful but potentially dangerous chemical.) Spread the resulting paste over the stain. The cleaner will sink into the concrete and slowly draw up the oil and grease, and the absorbent powder will absorb it. Once the mixture has dried, scrape away the paste using a brush. Depending on the strength of the mixture and the stain’s resistance, multiple coats may be necessary to fully penetrate and absolve the area.
If you have gotten paint on your driveway and it has only absorbed into the concrete’s top surface, a high-powered pressure washer may be strong enough to chip away all paint particles. If the pressure washer is unsuccessful, use an electric, heavy-duty sander with coarse grit sandpaper and evenly smooth over the affected area to loosen the paint’s hold.
Another option is to mix a portion of absorbent material with chemical, industrial-strength paint thinner, once again creating a paste. Wear a respirator mask, and if applying to concrete inside a garage, open the doors and facilitate ventilation to ward off fume buildup. After the paste is applied to the painted area and dries, scrape it away and the remaining paint flakes should come with it. Repeat as needed to achieve the desired result.
Rust can be one of the most difficult substances to remove from concrete. First, mix one part TSP with one part water. Soak the rust-covered surface, then scrub with a wire brush. You can also try using vinegar or lemon juice in place of TSP and water.
For stubborn rust stains, breaking down the surface of the concrete with a muriatic acid mixture may be the only effective removal tactic. Put on layers of protective eye, hand, feet and body gear. Pour two cups of water into a plastic bin and add ¼ cup muriatic acid. Never pour water into acid, as that combination boils quickly and can splash hot acid all over. Apply a thin coating of the mixture and attempt to scrub the rust away with a long-handled brush. Add additional coatings of the acid mixture sparingly, in small doses. While it’s important to remove ugly, orange-colored rust stains, the goal is to preserve the concrete rather than cause it to crumble.
Never pour bleach on rust stains – it only sets them more permanently in the concrete. Before using any industrial-strength cleaner for any type of stain, perform a small test on a corner of your driveway to make sure the cleaning agent itself won’t create a stain. For expert concrete repair and more advice on cleaning concrete stains, contact the Lift-Up Concrete team today.