Recently, I have been watching The Beverly Hillbillies episodes from Archive.org (https://archive.org/details/classic_tv?and%5B%5D=subject%3A%22Beverly+Hillbillies%22). In its first episode, there was a reference to home-made “lye” soap. Apparently, Sodium Hydroxide (NaOH), a base, is called lye. Mixed with a limited quantity of water, it becomes an extremely hot and reactive state called lye water. Lye water when mixed with a combination of oils (base + acid) becomes a more stable form that can be used as a soap. In Western countries, they use animal fat such as lard for the oil part. Coconut oil is the best choice to make soap. Most companies use cheaper palm oil.