Slate is a natural stone that comes from the earth. When used for a fireplace hearth it evokes a classic, earthy appearance. Because slate is a natural material, it's porous in nature and absorbs stains. Surface and older stains can be cleaned from slate by drawing them out of the stone. This must be done carefully and properly in order to not damage your fireplace hearth.
Mix commercial smoke remover for natural stone fireplace hearths in a bucket, according to directions. Wash the surface of your slate hearth with the solution to remove surface dirt, soot and stains.
Rinse the cleanser off your slate hearth with a damp sponge. Towel dry the slate stone with an old towel.
Pour baking soda into a bowl and add enough white spirit to create a thick paste. Stir the two ingredients together with a spoon. Apply the paste over any remaining stains on your slate hearth.
Place cling film over the paste and tape it down with masking tape, if needed. Let the poultice paste dry on the surface of your hearth to draw out the remaining stains.
Remove the cling film and poultice with the scraper. Discard the paste and remove any poultice residue by washing the slate down with a damp sponge. Allow the slate to air dry completely.
Rub boiled linseed oil into the slate stone to polish and protect it. Buff out excess oil with an old towel.
Wipe your hearth immediately if anything is spilt on it, such as wine or other drinks. This will prevent the stain from being absorbed into the stone.
Avoid using vinegar to clean a slate hearth as the acid in vinegar can damage the natural stone.