Flagstone/Sandstone Cleaning process is used because they are porous, durable sedimentary rock composed of cemented sand-sized grains, predominantly quartz with silica, iron oxide or calcium carbonate. Flagstone/Sandstone Cleaning in used for countertops, flooring, showers, porches, stepping stones, pavers and vertical surfaces. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, gray and white unlike most man-made tile floors.
Sandstone ranges from 6 to 7 on the MOH scale (a scale for determining the relative hardness of a mineral according to its resistance to scratching). The hardest mineral, at 10, is diamond. The softest mineral, at 1, is talc.
Pennsylvania Bluestone, a type of sandstone, is denser and less absorbent than Flagstone and is a gray blue with medium to high absorption
Shenandoah Valley Bluestone is limestone, not sandstone! The stone eventually fades from a deep blue to a light grey after prolonged exposure to the sun and rain. Remember, limestone is acid sensitive while sandstone is not. Bottom line: TEST first!