How hydroxide dismantles fats
Lye is a common name for strongly alkaline compounds such as sodium hydroxide. In water, they release hydroxide ions, which react with the chemical bonds that hold many biological molecules together. In fats, hydroxide breaks the bonds linking fatty acids to glycerol. The products are glycerol and fatty-acid salts—the molecules that make soap useful for surrounding oily grime and helping it mix with water.
This reaction is called saponification. It does more than loosen grease: it converts much of the fat itself into substances that can disperse or rinse away.
Why living tissue is vulnerable
Tissue is not just fat. It also contains proteins, which fold into shapes that let them perform their jobs and help form structures such as skin. A strongly alkaline environment disrupts the interactions that maintain those shapes; given enough exposure, it can also break protein chains. As fats and proteins lose their structure, tissue can soften and come apart.
The effect depends on the material and the conditions. Lye does not dissolve every organic substance in the same way, and a reaction at a tissue surface can be slowed by the material already broken down there. But contact can still cause deep, severe injury: the chemistry that makes lye effective against greasy organic matter is also capable of damaging the living material that protects the body.
