RUST!!!
Basicly spary on, loosens the rust till it comes off.
Then you need to repaint the area so that it doesn't rust again, and so that it doesn't look bad (just a blank spot of metal)
So tape of the area, prime it up, and then add another coat.
I have little experiance in this, so I can't give any times. If its just small spots you can use touch up paint, if its bigger it might be tuff to get it even with the rest of the paint.



