Black Magic marker on a white marble floor. Tar tracked on your granite floor from construction crews. Rust stains appearing in your limestone shower. Mysterious yellow spots appearing all over your marble countertop. These are just a few of the countless varieties of actions which can result in the staining of marble, granite and other stone surfaces. Is the stone ruined? Does it need to be replaced? The answer may be “yes†unless you know the techniques that will remove most imbedded stains from stone. Marble and other natural stones are porous materials. This porosity is why they stain so easily. It is also why stains can be removed. In many cases, a stain can be removed simply by reversing the staining process. In other words, since the stone has literally absorbed the stain, we can re-absorb the stain into a different material. This different material is referred to as a “poultice,†and it can be made with powdered whiting (sold in most paint stores) and hydrogen peroxide or a chemical reducing agent, depending on the nature of the stain. The poultice should be made and applied as described for removal of each particular stain.