a lot of that black stuff is powder coated and that make the finish tougher than just regular paint. I even try some mineral spirits and a tooth brush. In a less visible spot of course.Yeah I tried washing it and it didn’t come off. I thought maybe it was moisture causing some form of rust but then it was only on the frontside. Let me see if I can remove it. Goo off, Wd-40? Thanks for the insights.