Rescue HSR-100 Hardwater & Calcium Remover RESCUE HSR1OO is a safe citric acid-based formula quickly dissolves dried-hardened calcium and lime deposits, tarnish and rust on glass, porcelain, metals, tile, vinyl and stone surfaces. Use on windows, bath/kitchen fixtures, household appliances, dishwashers, porcelain and granite, shower tile and glass, and aluminum frames. Safe near vegetation and in septic/sewer areas Safely removes concrete splatter on windows, and metal surfaces. Effective on drinking fountains, metal mullions and sculptures