Smartseal Xtreme Natural Stone Cleaner is a professional grade cleaner specially formulated for the quick removal of black spot, mould, mildew, green algae and general surface staining from all types of natural stone. Suitable for use on: Sandstone Black Limestone Granite Slate Marble Travertine Quartz It is used widely by homeowners as well as professional cleaning companies to clean most types of natural stone without the need for intensive pressure cleaning. It's an easy to apply, fast-acting formulation, that leaves outstanding results and makes natural stone cleaning easier than ever before. Unlike acidic based cleaners, this powerful alkaline cleaner can be used on all types of natural stone without risk of damage to the surface.