Bath, shower, and other wet areas: Soap scum can be minimized by using a squeegee after each use. To remove soap scum, use a non-acidic soap-scum remover or a solution of ammonia and water (about 1/2 cup ammonia to a gallon of water). Frequent or over-use of an ammonia solution may eventually dull the surface of the stone. Vanity-top surfaces: Vanity tops may need to have a penetrating sealer applied. A good-quality marble wax or non-yellowing automobile paste wax can be applied to minimize water spotting.