A major difference between making liquid soap and bar soap is that that it is a "hot process" soap. Instead of relying on the heat generated by the saponification process, heat is added using a double boiler, oven, or crockpot. This recipe can be made in a double boiler or the oven, but a crock pot is preferred. It keeps everything in one pot and lets it cook evenly without having to monitor the water in a double boiler.
Begin the Soapmaking
Measure out your oils and put them in the crockpot on low. You want this mixture to be at about 160 degrees (give or take 10) throughout.
While the oils are heating up, mix your lye-water, using the standard lye-making procedure. If you've never used potassium hydroxide before, don't be alarmed. It's a bit more volatile in the water than sodium hydroxide. It makes an odd boiling/groaning sound as it's dissolving. This is normal.
When the lye-water is completely mixed and clear, slowly add it into your oils. (You don't need to wait until it is cool.) Don't turn the stick blender on just yet. Just stir the oils and lye together. Then, like in cold process soap making, start using the stick blender. At first, it will seem to want to separate. Keep blending.