Limestone is a beautiful stone often used in counter top and flooring applications. While we often think of stone as being hard, it is also a porous material. This means that spills have the potential to cause stain problems because the limestone may absorb the spilt substance. If you have a limestone surface that has been stained, there is a method you can use that is usually effective in removing it.
Don rubber gloves and safety glasses, as you will be handling chemicals.
Determine the nature of the stain so that you may use the proper chemical when mixing the cleaner in Step 3. For both organic and inorganic stains, use a strong hydrogen peroxide solution. This type of hydrogen peroxide is not available in chemists, you will need to go to a beauty supplies shop. Ask for a "clear developer" in either "30 volume" or "40 volume" strength. This is actually 9 per cent and 12 per cent hydrogen peroxide, respectively. For oily stains, substitute simple acetone for the hydrogen peroxide.
Add talcum powder to a glass bowl and add small amounts of either the hydrogen peroxide or acetone while mixing with a metal spoon. The idea here is to create a toothpaste-like consistency.
Apply the mixture to the stain so that it overlaps the stain by about 1.3 cm (1/2 inch), and so that the paste is 6 mm (1/4 inch) thick. Cover it with cling film and tape down the wrap at the edges with masking tape.
Let the mix work on the stain for 24 hours. Remove the cling film and then let the mix dry out. Allow it to dry completely without disturbing it. Depending on conditions, this may take up to a few days.
Remove the mix from the limestone surface once it has completely dried, using a plastic spatula. Wipe the area with a paper towel and a little bit of a cleaner that is meant for marble, granite and limestone surfaces. Your stain should be gone. Repeating the entire process is often helpful on stubborn stains.