Don't read on if you are of a delicate disposition.
I knew under certain conditions human fat from buried corpses could turn to what is in effect soap. It's called adipocere and the chemical process that causes it is in effect, saponification. Some gruesome things I've come across include the fact that this adipocere can be useful if bodies are exhumed because of suspicious circumstances because it can retain evidence of cause of death. It was a feature of a famous case about the murder of two children many years ago (the Higgins brothers) There is a body in the USA in a museum known as the "soap lady" whose body and clothes have been preserved to some extent by a coating of soapy wax. I also read recently about a German cemetery which wanted to dig up the bodies to install the bones in an ossuary so they could reuse the graves but found the bodies in a high state of preservation because if this stuff. I don't know what they did. I think it happens when bodies are buried in damp, alkaline soil so you get a chemical reaction similar to when fat meets lye.
Human fat has been deliberately used to make soap. Apparently (I read online so who knows if it's remotely true) an Italian artist made a bar of soap, allegedly, from the siphoned body fat of Silvio Berlesconi "obtained" from a Swiss cosmetic surgery clinic. At least he was still alive. There was also a famous case in the 40's of an Italian lady who murdered three women (as a sort of human sacrifice to act as a charm to protect her son from the war) rendering their fat to dispose of the bodies. Being thrifty, there was a war on after all, she made some fine white soap and biscuits which she kindly gave to her neighbours!
I don't think you are likely to find human fat in any soap making calculators! Apologies for the gruesome stories. I blame my father, bless him, who let me read his books on murder and famous pathology cases when I was quite young and left me with an interest in the weird and gruesome.
