Do ALL soaps contain alkali?
In a properly made soap, the NaOH or KOH (aka ‘base’) is consumed. NaOH or KOH is necessary to chemically turn oils and fats into what we consider soap. The amount of base required to turn the oils and fats into soap various from oil to oil and fat to fat, but can be calculated using saponification charts. If any base remains after the soapmaking process, the soap can be caustic and burn the skin. The oils and fats used can be vegetable or animal based. Castille soap, by definition, is made with 100% olive oil, converted by a base into soap. (The base is necessary – otherwise, it would be just plain-old liquid olive oil.) What is left over might have a small amount of olive oil in it, but no base. There are literally hundreds of different types of oil that can be used, varying from hemp and apricot to beef and emu. The type of oil used gives the soap different properties. Coconut oil gives lots of lather. Soybean or Crisco makes it harder. So forth and so on. Sometimes, an oil is added
