A lye is a metal hydroxide traditionally obtained by leaching wood ashes, or a mighty alkali which is highly soluble in water producing sour basic solutions. “Lye” most commonly refers to sodium hydroxide (NaOH), but historically has been used for potassium hydroxide (KOH).
Today, lye is commercially manufactured using a membrane cell chloralkali process. It is supplied in various forms such as flakes, pellets, microbeads, coarse powder or a solution. Lye has traditionally been used as the main ingredient in soap making.