Propylene glycol, so it didn't dry out, boric acid or sodium nitride so it didn't get rancid. Most of the time it was boric acid as I used that and flux when soldering to keep the gold or silver clean, when doing jewelry repair for a jeweler friend. I had a lot of different training as I started working young in life and was anal retentive about how to do things better. So I studied a lot of different things and asked people who did different things to teach me a little about doing it, but also a lot of the time I just observed and kept out of the way. So many people think if a little bit will do more will be better that's not the case here for sure. And when you are making your scent mound it's the same, I would make my mud mound and then find a small twig about an 1/8 inch in diameter and 2 inches long dip it in my castor then lay it on my scent mound. The location of the mound close to where they are traveling and not far from the water's edge but high enough not to be affected by water levels changing. I never tore out the dam unless it was stopping irrigation of a crop. As with all of my trapping I tried to not make much sign that I had been there just my scent posts of the animal not me. I always said that I wanted to act like that if I was caught by the animal in their area they would shoot me. But I had one guy that didn't like that saying, he didn't understand that it was just saying leave as little sign of you being there as you can!