A Non-Acidic Masonry Cleaner! A concentrated masonry cleaner designed to penetrate and emulsify the products of combustion, smoke, soot and creosote. Contains a heavy-duty surface cleaning surfactant for emulsification of greasy dirt, an industrial-strength solvent for dissolving creosote and sooty build-up and a builder for rich suds. Safe to use. Will not harm metal, glass or fiberglass gaskets.Try on a small portion of hearth before using to check compatibility of cleaner and cleaning method with the masonry surface.