Removing stains on limestone?

Post date: 2024-08-07 03:54:15

I stained my limestone front steps with cork-based "coasters" for flowerpots. How to remove?

I stupidly used cork-based mats or coasters underneath flowerpots on my new-ish limestone steps. I soaked the cork beforehand to try to stop staining, but it didn't work and the coasters left brown circles on the stairs - like big coffee cup stains. The stains are about 2 weeks old. I tried powerwashing and some different household products, which removed some of the staining, but maybe like 50%. The most effective thing seemed to be Softscrub, which has bleach. I am worried about ruining the stone with too much bleach or acid or whatever. The stain is definitely in the pores of the stone - i.e., the powerwasher does not take it off.

After some research on the web, I have three methods that I and thinking about trying: (1) a homemade poultice made from baking soda and 12%-strength hydrogen peroxide, which you are supposed to leave on the stone for 24 hours (I am worried about overbleaching though); (2) a professional stone cleaning soap made by Black Dimond; or (3) leaving on the Softscrub for an hour or so before rinsing it off - the Softscrub seemed effective before, though it also seems harsh.

Any thoughts on these methods or others? Thank you!

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