Hey guys, I'm about to be done sanding and stripping my paramount and was wondering if you could help me out.

The frame had a few rust spots and I have sanded them down to the metal. However, even after sanding, I can still see some tiny black dots where the rust spots used to be. I was wondering if there is a primer that would prevent those tiny spots from spreading again. I was reading about rust-oleum but would that work on the long run? I've read in the forum that some people have treated stuff like this by sinking their frames on oxalic acid but I don't want to go through that trouble unless it is absolutely necessary.