GST's Efflorescence Remover is used to remove the white chalky deposits known as efflorescence found on concrete & masonry surfaces. Efflorescence Remover is a water soluble, biodegradable blend of non toxic acids and surfactants used as a safer alternative to the highly reactive muriatic acid (hydrochloric acid). It can also clean and brighten newly placed masonry construction by removing mortar residue and properly prepares surfaces for the application of one of GST's contractor grade protective sealers. Also, effective in removing mild rust stains from concrete. Efflorescence is a white crystalline deposit that is composed of water soluble mineral salts and are common where cementitious or alkali substances exist. These minerals travel to the surface, carried by water as it migrates through cementitious substrates by a process called capillary action. Once the solution of water and minerals arrives at the surface, the water evaporates leaving behind the salts know as efflorescence.