Lye (also known as caustic soda) is a corrosive alkaline substance, commonly, sodium hydroxide (NaOH). Previously, lye was among the many different alkalis leached from hardwood ashes. Now, lye is commercially manufactured using a membrane cell method.
Solid dry lye is commonly available as flakes, pellets, microbeads, and coarse powder. It is also available as solution, often dissolved in water. Lye is valued for its use in food preparation, soap making, biodiesel production, and household uses, such as oven cleaner and drain opener.
Lye is used to cure many types of food, such as: lutefisk, green olives, hominy, lye rolls, century eggs, pretzels, zongzi (Chinese glutinous rice dumplings), and Chinese noodles. Lower grades of lye are commonly used as drain openers and oven cleaners and should not be used for food preparation. Lye is a heavy duty alkali at about 13.0 pH.