Typically, to apply a poultice, you stir a liquid — sometimes just water — into a powder, such as cornstarch, baby powder, baking soda or one of the many poultice preparations made for stone care. When the mixture has enough liquid to reach a paste consistency, you spread it like peanut butter over the stain and wait. The liquid sinks into the stone and dissolves the stain. Then the liquid moves to the surface as it evaporates, pulling the stain ingredients along for the ride. When the paste finally dries, the crust contains a significant amount of what was causing the stain. After wiping or vacuuming that away, if you still see stains, you can apply one or more additional poultices. With a fresh stain, you might be able to remove nearly all the color. With an older stain, some of it might be permanent.
Numerous stone-care companies sell stain-removal products suitable for use on marble. MB Stone Care in Wilson, N.C., for example, sells a kit with a premixed poultice, stain reaper, and a surface cleaner and oxygenated bleach called Easy Oxy for $48.97.
But Stuart Rosen, owner of MB Stone Care and a stone-restoration company called Stoneshine in Haledon, N.J., suggests using a homemade solution on your sink. The big change: Instead of using a paste, he suggested making a pad of six to eight layers of paper towels. With that, there’s no risk of getting powder or paste down the drain, or of using ingredients that might stain marble.
For the liquid, he recommends food-grade hydrogen peroxide at 35 percent volume, which is a far more powerful bleaching agent than the 3 percent volume hydrogen peroxide sold in drug and grocery stores. You will probably need to order the more concentrated type online; it’s not usually sold in stores. A 16-ounce bottle lists for $29.99 at bulkperoxide.com. Larger sizes are available, but you’ll pay a hazardous materials fee for containers of a gallon size or larger. It ships by ground regardless of the container size. At this concentration, hydrogen peroxide will burn skin. Wear goggles and protective gloves and clothing when using it.
Rosen recommends placing the pad of paper towels over the stain and pouring on just enough hydrogen peroxide to saturate the paper towels. “With a gloved hand, work it in thoroughly,” he says. “It should be not dripping, but wet.” Cover the paper with plastic so the liquid has time to sink into the marble before it evaporates. In a day or so, check whether the paper is dry. When it is, peel it back. Some — or maybe even all — of the black color should now be in the paper, and your sink should look a lot better. Repeat the procedure if the stain persists, until you aren’t making any more progress.
One detail that you might overlook: It’s essential to wait until the paper (or paste, if you’re using other ingredients) is dry. Evaporation is what gets the stain out of the stone.
Rosen says he is confident of this procedure because he recently used it to help a family with a son who wanted to dye his hair red. The bottle popped and red dye squirted all the way to the ceiling. Rosen got a call for help on a Friday. He applied the paper towels and hydrogen peroxide. On Sunday, the homeowner called him to report that the paper towels had fallen off on their own and that “99 percent of the stain came off.”
Rosen learned about poultices as a child, from his grandmother. If he spilled grease or oil on his clothes, she would sprinkle on some baby powder and work it in. A few hours later, the fabric would be clear of grease — it had moved into the powder. It awed him. “Poulticing is pretty close to witchcraft,” he says.
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