A: You are not alone in facing this problem. Red clay soils are very common throughout much of the Southeast, with narrower bands in western Oregon and Washington and parts of California. Red clay soil – classified as “Ultisol” in the United States Department of Agriculture’s 12 major soil types – gets its color from oxidized iron, also known as rust. Rust does not dissolve in water, making red clay stains very difficult to remove. And clay particles are very small, so they easily penetrate porous surfaces, including fabrics, concrete, and other masonry materials.
Bleach, which is alkaline, will not eject rust stains, so it is useless against red clay. Some acids, which have opposite chemistry, remove rust and red clay. Products labeled specifically about clay often contain both acids and surfactants – soap-like ingredients that help eject clay particles and keep them in suspension until they are rinsed.
If you’re dealing with fabric, pre-soaking with detergent and perhaps oxygen bleach is key to getting rid of red clay. The Tide and Clorox websites suggest a similar process: Use cold running water to rinse away any clay you can’t brush off, pre-soak or treat with stain remover, then wash.
For pre-soaking, the Tide website recommends submerging the item in water with a little Tide detergent, or pouring the full-strength detergent onto the stain and waiting five minutes before adding the detergent. This item has one wash load with one to three Tide Oxi pods, depending on load size. Clorox recommends using one measure of “good powder detergent” in 2 gallons of hot water for a one to eight hour pre-soak, rinse then pretreat the stain for 10 minutes with Clorox 2 For Colors Stain and Laundry Additive. Then, Clorox says, wash on the hottest setting with detergent and more additive, which contains hydrogen peroxide, an oxygen bleach.
Or you can pretreat with a product labeled to remove red clay or rust, such as CLR Laundry Stain & Odor Remover (the new name for what was CLR Sports Stain Remover, $3.99 for a 22-count spray bottle ounces at Do it Best Hardware) or Iron Out Rust Stain Remover ($8.99 for a 28-ounce bottle at Ace Hardware). Iron Out is safe for whites but can remove dye from colored fabrics. (A caution: Make sure ventilation is good enough to avoid breathing in vapors after adding water, and avoid using this product completely if you have respiratory problems or are sensitive to sulfites .)
Whatever cleaning products you use, air dry the items, if possible, so you can repeat the process if you later notice any stains you missed. The heat from the dryer can make stains permanent.
Sorting through options to find the best way to remove red clay stains from concrete is trickier, in part because concrete mixes and finishing methods vary. Always test a small area, rinse well, and wait until the next day to assess whether the cleaner has caused any damage.
If you already have a rust remover, including one for fabric, try that first. If you must purchase one, look for a statement that it is effective against red clay and read the application instructions to make sure they are appropriate for your situation. Some stain removers are labeled for outdoor use only, minimizing the risk of inhaling dangerous vapors where ventilation is not as good. Some products need to be rinsed with a power washer – a problem in a garage with many boxes stored. Other stain removers include warnings not to use them on stained concrete or concrete less than a year old. Many are designed for use on vertical surfaces where rinse water flows, not on horizontal surfaces like garage floors, where rinse water can puddle.
EaCoChem, which sells a range of cleaners to professionals, markets its OneRestore cleaner for removing red clay stains and for general cleaning of concrete, glass, unpolished stone and brick. It works without scrubbing, but the cleaner is very acidic, so paying attention to safety concerns is essential.
Lynn Peden, owner of EaCoChem, said that for homeowner application, especially in an environment such as a garage floor, a more suitable product would be the company’s HD Britenol ($41.99 per gallon on windowcleaner.com). Britenol is less acidic and slower acting than OneRestore, Peden said, but the safety benefits are worth it. He suggested diluting it by mixing 10 parts water to 1 part Britenol. “If it doesn’t work, use it directly.” For a test area, he suggests measuring the ratio by traffic jams. Even though this cleanser is gentler than OneRestore, it still contains hydrochloric acid. It is essential to protect your skin and eyes and avoid wearing contact lenses when using it.
First moisten (but do not saturate) the concrete with water. Spray the cleaner with a spray bottle. “Squirting can be slow, but it’s better,” Peden said. This increases the dwell time, especially if you go back and spray a second time a few minutes later. Work on areas small enough so the cleaner doesn’t dry before rinsing with a bucket of water and a mop. Dispose of water wrung out from the mop into a sink or other drain, even if your home has a septic tank, but don’t throw it into a storm drain or onto the sidewalk that leads to a drain, Peden said .
CLR Calcium, Lime and Rust Remover is a more commonly available cleaner that works on rust stains ($6.99 for a 28-ounce bottle at Ace). A spokeswoman for Jelmar, which owns the CLR brand, said the company hasn’t tested the product specifically on red clay stains, but has been told by customers that it works. She suggested diluting it half and half with water for a test, then over a larger area if the test shows no damage. Moisten the concrete, apply the cleaner, wait no more than two minutes, then scrub with a brush and rinse with cold water. Avoid using this product if the concrete is stained, sealed, or less than one year old.
If your garage floor is sealed, water should bead up rather than running into it. If it is not sealed, applying a sealer should help prevent future staining. First make sure the concrete is clean and dry. Familyhandyman.com has a good how-to guide.
If you can’t completely remove the stains, consider applying a red concrete stain to the floor and then sealing it. The spots look ugly, but they would be much less visible against a reddish background. And any future red clay stains would probably blend in better.
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