It could be the pink ring around the waterline in the toilet, the pink grout lines on a tiled shower wall, or the red slime on the ledge where the shower walls meet the bathtub, all of these bacteria.
It is usually possible to scrub these colonies with soapy water and a hairbrush. An old toothbrush works well in crevices. But when natural stone, especially relatively porous marble, is etched with acidic cleaners or not topped with a sealant, bacterial growth can extend into the stone’s pores and be impossible to scrub away.
John Forgoson, general manager of My Stone Care in Santa Ana, California, which sells stone care products through mystonecare.com, looked at the pictures you sent and said he thought the built-in bacteria could be a big part of your problem. He said rust spots from water reacting with iron in marble could also be a factor.
Forguson recommends starting with a solution of half chlorine bleach and half water. Put on gloves, goggles, old clothes you don’t mind seeing from the bleach, and open a window. Wet the marble in the solution and set the timer for five minutes. At this point, wipe off the bleach solution, rinse it several times with plenty of water and dry it with a towel. If the spots have faded but are still visible, repeat the process until the spots are gone.
If you start seeing orange or brown spots as the red fades, rust may be a factor. As a natural stone, marble often contains traces of various elements. Rust can form when iron is in the stone and moisture penetrates.
To remove rust, you need a rust remover – but you can’t use most of those on the market, because they are very acidic, and acid solutions corrode the marble. Forguson recommends ConfiAd Rust Removal Gel ($37.95 a liter mystonecare.com). Lithovin’s Rust-EX non-acidic rust stain remover, which the company also sells for ($19.95 a bottle), is another safe option for marble, but it’s not nearly as strong and isn’t easy to use, since it’s a liquid, he said. . The gel “stays in place”.
With either product, you’ll see purple spots almost immediately if iron is present. This is a sign that the remover is working. After five to 10 minutes – no more than that – wipe off the residue and rinse thoroughly. Over the next couple of days, assuming there is iron in the stone, the spots should continue to bloom. If they are still visible, repeat the process until there is no further improvement. Wait several days between treatments.
If you don’t see rust spots after you’ve finished the initial treatment with a bleach solution, or if you’ve tried one of the rust removers but nothing turns purple, you’re probably just dealing with bacterial staining and the growth is too deep to get with a liquid cleaner. In this case, Forgesson recommends applying broad-spectrum compresses. He recommends StonePro Wet Stain Remover ($31.95 per pound at mystonecare.com).
A YouTube video created by StonePro says he spreads the compresses a quarter inch thick over the patches and about a quarter inch after that, then to cover the paste with plastic and either tape down the edges of the plastic or embed the plastic in the edges of the poultice paste, so you make a seal.
Forgeson said he found it helpful to first mix the hydrogen peroxide into the paste, using a ratio of 20 drops of hydrogen peroxide per tablespoon of the paste. Wait 18 to 24 hours, then carefully pull out the plastic without removing the putty, and let it dry until the putty is a powder that you can remove. The video says this will happen within 24 hours; It will take approximately 48 hours, said Forgosson.
Wait for the stone to dry completely, which may take another 18 hours. If the spots seem lighter but have not gone away, repeat the compressive procedure.
Once the stains are gone, apply a stone sealant. After you continue to use the sealer, you won’t be able to try more stain removal options—except for a professional to sharpen the stone.
Besides, you have two other options: replace the marble, or decide to live with the stains. If this is your only shower, you may choose to live with it, unless you can come up with a strategy for showering elsewhere during the many days that the multi-step replacement process can take.
Do you have a problem in your home? Send questions to [email protected]. Put “How To” in the subject line, tell us where you live and try to include a photo.