Potential Problems Removing Rust Stain on Marble

When poulticing a rust stain on a marble floor, the stain can become darker and more wide spread. What is happening? Chances are the source of the rust is under the tile. A nail or metal object may have been left behind when the tile was installed. The reason the rust gets darker is because the poultice is pulling the rust from the bottom of the stone to the top. Remove the tile and find the source of the rust.

It is also possible that the darker spot is simply moisture. Try placing dry poultice on the dark area. Allow this to sit for 12 to 24 hours. If it is moisture, the dry poultice should wick it out.