Make sure you use 100% lye. A lot of drain openers have other stuff in them too.
If you do hot process, you can use it the next day. Basically you cook the soap until saponification is complete. Put in mold, cut when cool, use.
I cook a lot of bacon, so I end up with a lot of bacon fat - more than I can use cooking. So I make soap out of it. I also throw some coffee in there - save a couple of used espresso pucks. Finally, throw some salt in the soap at the end of the cook - this’ll help it harden so that it doesn’t wash away in your first shower.
