Ok, so I'm catching up on a backlog of photos I've been meaning to post. How did you guess?
Here are some photos of me rendering tallow. I went to Albertson's and asked the butcher folk for some beef fat. They said come back later and they'd save me some. I did, and I came home with a couple pounds of fat. I cut it into cubes and put it in my dutch oven
then stuck it in the oven at 225°F for awhile. Nothing really happened. A little melting. This could take all day. So I put it on the range top and added water and brought the mess to a boil. I let it boil for awhile. It smelled about like boiling stock, if you can imagine that. After awhile, I declared the low-hanging fat picked, and poured the liquid through a collander into a receptacle which I put in the fridge after it cooled off somewhat. The next day I poured off the water. Et voilá! Tallow.
I made one bar of soap with it (and olive oil and coconut oil and a couple drops of pine essential oil), and though it hasn't yet fully cured and I haven't truly used it yet, it does smell a bit like beef fat. Or that might be my imagination. So I simmered it again in fresh water for about 4 hours, then refrigerated. This time it was a bit whiter. I made another bar, with basically the same ingredients (sans pine essential oil) but also with a bit of cocoa butter. Again, I haven't truly used it yet, but it seems to smell better.
If I do it again (and I may, if I like the soap), I'll do a larger batch, and I'll do some things different. First, I'll ask them to grind it for me. Hopefully more surface area will mean faster melting. Then, I'll first cook it dry on low heat for a time, kind of like cooking bacon. Or perhaps in the oven at a bit higher temperature. When I reach the "low-hanging fat" point, I'll pour it off into some simmering water and simmer it for a couple of hours. I'll let that harden, and simmer it for a couple of hours again. If I'm in no hurry, I'll do it a third time. Then I'll have lot's o' tallow that I'm confident is nice and pure.