We bought a half a beef last fall. They asked if we wanted the scraps, and since I believe in using every part of the animal (since it died for us, I don't want to waste any part of its life), we said yes.
I surmised that the 'scraps' would be soup bones and the like.
I was wrong.
We got a box full of, well, scraps. There was some bone (which did go to make stock of course), but most of it was fat. Cows are fatty animals in case you didn't know or have forgotten (and there is nothing like a whole box full of fat to make sure that I will never ever forget!)
So what does one do with a whole bunch of cow fat? Well render it into tallow and make candles of course!
First, all that fat/gristle/unknown stuff has to be chopped into little pieces (you can see the box there behind my bowl of bits--it was pretty full).
Second, put the bits in a big pan with some water, and boil for a loooong time until all the fat becomes liquid (keep an eye on it, because the water will boil off and then things get ugly and stinky and just generally bad...)
Pour the contents of the pan out through a strainer. BE CAREFUL, THIS STUFF IS REALLY HOT!! The things I read recommended straining twice, which I did (once with a bigger-hole metal colander and then once through a fine-mesh strainer). Once it is well strained, pour the remaining liquid--which will be murky--into a dish to separate and cool. The water and fat will separate and the fat will rise to the top and solidify. Give it at least a few hours, I have had the best results with letting it go overnight. (I put it in bread pans here, the square shape made it easier to get the tallow block out later.)
Once the tallow is solid, use a table knife to separate the tallow from the edge of the container. Dump out the water into the toilet. (The bits of tallow will clog up your sink drains, it has to go in the toilet!!) Set out the tallow to dry/drain (I put it on paper towels). It usually seems to have some gunk along it where it bordered the water, so I use the table knife to scrape that scuzzy part off and put it in the garbage or toilet.
I like to let it air out for at least a few hours before using it. If you do not have immediate plans for it, put it in a bag in the freezer.
Coming next: part 2, making the candles!!