Ha! I just started an article on making deer fat lye soap. I need to make a batch now and get the photos of the various steps along the way.
Lye soap ain't nothing like the urban legends want us to believe. Properly made it is mild and effective. It does smell a little like animal fat, but you can always use any number of essential oils and fragrances to "pretty" it up.
As far as rendering, for soap I always recommend you put it in a roaster in the oven and cover it with water. Go low and slow, 250 degrees and overnight with the lid on tight. Strain, cool it, and let the fat separate and harden. For lubricant or waterproofing purposes, you can skip the water part and just roast it low and slow. It will be a little smellier, if you don't mind. Once you have the fat drained off the cracklings, boil it in water to clean it up if you have bits of floaties in it
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