Sodium hydroxide (NaOH), also known as lye and caustic soda, is a caustic metallic base. It is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner. Sodium hydroxide is a common base in chemical laboratories. Pure sodium hydroxide is a white solid; available in pellets, flakes, granules and as a 50% saturated solution.