Pickling

Pickling is a metal surface treatment used to remove impurities, such as stains, inorganic contaminants, rust or scale from ferrous metals, copper, precious metals and aluminum alloys. It’s called “pickling” because it involves the use of an acidic solution known as pickle liquor. The exact composition of the pickle liquor varies depending on the type of metal on which it’s used. For low-carbon steel, pickle liquor typically consists of hydrochloric or sulfuric acid. For high-carbon steel, on the other hand, pickle liquor typically contains additional acids like phosphoric and/or nitric acid.