JND Enterprises

Although limestone and marble substrates are self cleaning stones, many areas of a building are never exposed to rainwater. Over a period of years an encrusted black substance, chemically identified as calcium sulfate (gypsum), will form under cornices and belt courses. Unfortunately, the few chemical cleaners that can attack these encrusted areas aren't very effective in removing heavily encrusted areas. The calcium sulfate can be solubilized and removed however by a prolonged soaking or misting of plain water.