I have two questions regarding the first stage of traditional soapmaking, which, according to a bunch of DIY websites, is to make "lye water" out of "hardwood ash". Firstly, the 'pedia article on "wood ash" says that "potassium hydroxide [aka potash lye] can be indirectly made from wood ash by the addition of calcium hydroxide [aka slaked lime]". However, none of the instructional pages mention lime at all, just the ash and plenty of water - preferrably rainwater or some other kind of "soft water", i.e. water which has few mineral impurities, according to my understanding. Presumably, then, the hydroxide comes from the water itself, rather than from something else in the ash or from trace substances in the water, in this case? If both methods work, what is the advantage of using the calcium compound, when it's bound to be harder to obtain than ordinary rainwater? Secondly, is "hardwood ash" preferrable simply because it contains more inorganics like potassium, and is this what made the wood harder in the first place, as the name suggests - or is it more complicated than that? In principle, can ashes other than those of wood be used for this process, or is there something special about wood ash? Case in point, there is a folk etymology that derives the word "soap" from the legendary Mount Sapo, a site at which Romans supposedly burned animals as religious sacrifices. The resulting ashes, unburned (fatty) animal remains, and water from a nearby spring or stream then naturally combined, resulting in the creation and discovery of soap. Some versions of the story, including the one I linked to, specify that the ash in question was wood ash from the pyres, while others specify that it was the ashen remains of the burned animals themselves. To be sure, animals do contain some potassium, too (~200g for an average human, apparently), so could that work? Thanks in advance for any replies!