 You know what I'm saying is that residue would be in the tank and it would be staining. I know I've told this to several people about the breaking down of the rubber and they're like, you're crazy. And I'll tell you what, usually they call back and say that was it. It's not always it. If you go and you do touch that and you get like a little black, it's kind of a blackish or at least finished that's coming off.