ENVIRA® E-693 is an organic acid blend which is specifically formulated to remove coating materials which contains a lot of acid soluble contaminants. These include calcium carbonates, clay, pitch, rosin salts, urea-formaldehyde wet strength agents, alum, and hydrolyzed neutral size. ENVIRA® E-693 is extremely effective against calcium carbonate and manganese deposits. ENVIRA® E-693 also contains corrosion inhibitors and is safe to use with most metals.