Painting over rust on a car

Mai-Kero

So I was in an accident over a year ago, and one of the panels on my car had to be replaced. It was replaced with a charcoal grey stock panel that hadn't been painted, and I've never been able to have it professionally painted due to lack of funds and a need to pay for school. There's some rust starting to appear visibly, and I can rub it off with a finger, but I was wondering if there's any way to just get a cheap can of primer or something and spray over it to slow down the rusting process.

Any ideas?

Buttcleft

painting over rust is bad.

sand it down to clean metal, wipe it down with some alchohol to remove any body oils and dust, then hit it with the primer

Zeon

If you spray over the rust, the rust will still be there and it will eat away at the panels underneath the new paint. If you sand it down and prime it properly, thats good enough. There are write ups all over the place, search for "rust repair" and youll get a million hits.

*edit*, if its charcoal gray, its probably factory primed. DONT sand the whole panel down to bare metal. 99.999% of factory body panels are rust proofed at the factory. Tearing off the primer right down to bare metal will only accelerate the rusting in the future. You just want to get it down to bare metal in the areas where its already rusting.

Also, keep in mind, if you half ass it now, its only going to cost more to get it fixed properly in the future. Most body shops will not fuck around with your half ass job and try to get it right, or if they do, theyll charge you hours upon hours of labor time. A good body shop though will just strip it all down and redo it, which would still cost more than getting it done right the first time (ie, now).

wmelon

Keep in mind that most automotive primers aren't waterproof and are only there to provide adhesion for the top coat of paint. You'll need at least a clear coat to keep it from rusting right through the primer

KryptykSol

Seconding wmelon, unless thats a primer-sealer (unlikely) it is actually very porous, primers are supposed to be this way to "hold on" to the paint better. Unfortunately they also hold onto water as well. I would sand it down to metal where its rusting and hit it with some POR-15, which is a rust inhibiting paint that you should be able to find at any auto parts store. Then if you like you can paint over that with other paint.