How do I treat a small cancer spot on my car?

[Sabastien G]

I was washing my car today and to my surprise, there's a small bubbly cancer spot on the edge of the sheetmetal(by the tire). I bought car touch-up spray paint. what else do I need? How do i treat this small rust spot? Sand paper? Thanks in advance.

[baldie]

put your car on chemo. no, just kidding.get some heavy grit sandpaper and sand it clean down to the metal, if its got a small pin hole, take some spot putty and fill it, sand down the putty(after it dries good), spray it with some red oxide primer, wait until it dries good, take some light sandpaper and roughen the primer, then clean all dirt off and paint it.