This is a traditional method of soap production in which, as the name implies, the soap is boiled in a pot. It is sometimes referred to as the "saponification and salting-out method." The oil and fat are heated in a pot, stirred, and then combined with a caustic soda (sodium hydroxide) solution, which breaks down the oil and fat molecules into fatty acid and glycerin. The fatty acid bonds with sodium, and soap is produced. This process is called "saponification." After saponification, natural salt is added and the soap and impurity separated out. Salting out and still standing help the unsaponificates to react. This is followed by a final round of salting out that removes as many potentially irritating components as possible. Pot boiling method is a soap production method that has been passed down from generation to generation.