Understanding Lye: Its Role in Soap Making

Lye, or sodium hydroxide (NaOH), is a crucial ingredient in traditional soap making, yet it is often misunderstood. Despite its strong, caustic properties, lye is not only necessary for soap production, but it also plays a transformative role in the process that turns fats and oils into soap. Soap simply cannot be made without lye, and products that claim to be “lye-free” are typically not true soap in the traditional sense. In this essay, we will explore what lye is, why it is needed for soap making, and why soap made without lye does not qualify as authentic soap.