I have been doing a bit of research and even found out that you can make soap of lye made of wood ash
Yes mixing ashes with water produces lye which is one of the two components along with lipids necessary to start a saponification reaction. Some producers even keep some ashes when skimming the lye because of the slight abrasive properties of ashes.
Mariama said:
The soap the mother made was soft, BTW. :) Just saying, because people might expect it should be hard.
The hardness of the soap you make will depend on the kind of fat you use and on the lye saturation. Basically the longer the fatty chains are and the higher the lye percentage is, the harder the soap will be.
That's the reason why the soap labelled "pure olive oil" actually only contain about 70% of olive oil, the rest is usually palm oil. Soap that is only made of olive oil is very soft and when exposed to water it turns into jelly.
So home-made hard soap is feasible but you need the right fat mix and to dose precisely your fat/lye ratio. You put as much lye as possible but not too much otherwise the saponification reaction is incomplete and you will have untransformed fat in your soap.