You can tell you've been working on a car when after washing your hands several times and taking a shower, there's still dirt under your finger nails (even though I cut them 2 days ago) and the valleys of your finger prints are dark with grime. I don't know how else to get this stuff off. Soap has done all it can do. I've tried nail polish remover and rubbing alcohol. Now I'm just going to let time take care of it for me. I figure if it won't come off with soap, it's not going to come off on my food either.