Several household cleaning products contain lye (also known as sodium hydroxide). It is considered an alkaline and has a caustic quality. It causes fat and other sticky substances to dissolve; unfortunately, it tends to disintegrate other surfaces too (including human skin!) and should be handled with great care.
This lye is made by combining lime (calcium hydroxide) and sodium carbonate.
Traditionally, though, lye was made by burning particular kinds of wood (example: apple trees and oak) at a a temperature that would create white, not gray, ashes. These would be mixed with water and baking soda, and the lye siphoned off.
Today, manufacturers can purchase ready-made lye in flake, liquid or granular form. Lye’s caustic qualities make it an ideal cleanser, and it is often used to make personal soap, laundry detergent, metal polishers, pool supplies and drain de-cloggers. It is also a key ingredient in making paper and fabric.
Lye, or at least the products made with it, are a crucial part of modern living. What would civilization be without bath soap? Nevertheless, people need to remember that products with high lye concentrations—such as household cleansers—can still irritate the skin and can be fatal if ingested. It is very import to store them out of reach of children, and to follow all manufacturer’s instructions regarding proper use and proportion. Some products, such as drain de-cloggers, contain so much lye that even the fumes can be irritating, and can only be used in a room with adequate ventilation.