Muriatic acid is a form of hydrochloric acid that is sold in hardware and home improvement stores as a super-powerful household cleaner. It is a potent stain remover for residential swimming pools, bricks and other masonry, metals and toilets. But it can cause burns on exposed skin and eyes, and the fumes can be quite irritating to the lungs. You can use muriatic acid to clean porcelain, but it may damage the surface.
Always cover your skin and wear eye protection when you use muriatic acid. The Massachusetts Department of Environmental Protection recommends wearing acid-resistant gauntlet-style (long) gloves when working with muriatic acid. Use muriatic acid only in a well-ventilated area to reduce irritation from fumes. Use only water if you need to dilute the acid, and always add the acid to the water rather than adding water to the acid. Never mix muriatic acid with any other chemical or cleaning product.
Muriatic acid has long been used by professionals to clean unglazed porcelain and ceramic tiles. The Ceramic Tile Institute of America recommends against this practice, noting extensive injuries from acid burns and damage to decorative surfaces and metals from the fumes. The institute notes that acid-cleaning of unglazed ceramic mosaic and unglazed quarry tile can be accomplished with less dangerous acid cleaners.
Muriatic acid can clean stained porcelain toilets and help clear clogged drains. It can be quite effective for dissolving calcium deposits. Don't allow muriatic acid to sit in your porcelain toilet for an extended period of time, as it can damage the porcelain surface if used incorrectly. With the number of safer alternatives, muriatic acid should be a cleaning choice of last resort.
Muriatic acid can be harmful to the environment if not handled properly. Excess muriatic acid should never be disposed of by pouring it down the drain or putting a container of it in the trash. Always neutralize the acid prior to disposal by pouring the acid into a solution of 1 lb. of sodium carbonate and 3 gallons of water.