Anything but a hook and lead in the mold is too much to think about when things are just fine as they are. You need to goober up a mold, fine, have at it. I've been casting jigs for over 50 years and have never, ever sooted a mold or sprayed a release agent in one. I have a couple really, really old Do-It molds [red handles where there's still paint] and have cast them and did not have any issues with the jigs coming out. When I hear all this chit chat about release this and that I think of dirty lead. Still, I can see where the spray in agent might help the lead slip easier when you have a mold with a busy inner cavity. I just think that for the every day regular old jig caster like me nothing is needed.