The average cost of caustic soda or sodium hydroxide is $4 per pound. Having a wide application in chemical industry, it is often handled as an aqueous solution, as solutions are cheaper. About 60% of caustic soda produced is used by the chemical industry. It is also used for the manufacture of sodium salts and detergents. Caustic soda is also used in the Bayer process of aluminum production. Also known as lye, it is used in the manufacture of pulp and paper, textiles, drinking water, soaps and as a drain cleaner. It is essential to preserve caustic soda in air-tight containers as it is hygroscopic and readily absorbs water from the air.