Lye
Lye, a strong alkaline solution. Sodium hydroxide and potassium hydroxide are the two most common kinds of lye.
Sodium hydroxide, or caustic soda, is produced commercially through the electrolysis of a solution of sodium chloride (common salt) and water. Sodium hydroxide is used to make soap, paper, rayon, and detergents; in refining petroleum and vegetable oils; and in reclaiming rubber.
Potassium hydroxide, or caustic potash, is produced commercially through the electrolysis of a solution of potassium chloride and water. Potassium hydroxide is used to make soap; in bleaching textiles; and in producing other potassium compounds.
The chemical formula for sodium hydroxide is NaOH; for potassium hydroxide, KOH.