Howdy y’all, got a question for the hivemind. I am a pretty well versed hobby mechanic. I do most of my own work on my car, so I know my way around a wrench. Now what I don’t know my way around, is how to get the black staining/filling of the folds on the back of my knuckles, and my fingers. How do you all do it? My hands don’t leave marks on anything I touch, and they aren’t greasy. I use gritty oil breakdown soap whenever I get extra dirty, but I always find myself with a just bit of black nastiness left in the grooves of the skin on my hand. Is especially noticable on the knuckles. What ways have y’all found to combat this? I am just not rubbing my hands raw enough? Please enlighten me to the secret sauce.