Limestone is frequently used for floor tiles and countertops, and it stains with time and usage. You may use poultices to remove the stain, but do so extremely carefully.
Poultices typically consist of a powder and a chemical. Depending on the stain, the type of powder and chemicals used varies, but some common powders include talc, clay and whitening powder. Some commonly used chemicals include ammonium chloride, methylene chloride and oxalic powder.
Apply a layer of the poultice that is about 1/4 inch thick to the stain, then cover it with plastic, taping down the edges. Poke holes in the poultice so that it dries out. Allow the poultice to dry for between 24 and 48 hours and remove it, washing the spot with clear water and buffing it with a soft cloth.
Using a poultice on limestone can cause etching, where the acidic chemical eats into the limestone. If the limestone is etched by the poultice, use a limestone polishing powder and a piece of burlap to buff the spot back to its former brightness.