 mold in this case, although everyone will probably default to calling it that. I really think it's just a stain that should be easy to fix, but only if you attack it in the right way, Nicole. So what you need to do is you need to make sure that you are priming that spot where that nail is. And if it's a loose nail, I would put another one next to it so that the head is overlapped, and that will stop that loose nail from coming out any further.