I recently ordered some tallow to use as flux for stained glass. I found that it did nothing. It made my room smell like a hamburger, which was nice, but it did not help the solder adhere. I am sad because I thought this would be a better non-toxic flux I could use. I'm not sure why people say it does work, I have seen it multiple places on the internet. I used a product I bought online and did not make my own.