Oceanna our back railing is metal and I just painted it this summer. I cleaned it well with Naptha, wire brushed the rusty places and brushed on Rustoleum. Obviously I can't give you along term report on it but don't expect any problems. Using spray paint wouldn't work for me for 3 reasons: the overspray would have been an issue, I couldn't have my paint dude adjust a standard Rustoleum color to what I wanted and I wanted a thicker, more protective coating than spray would allow. I was able to apply the paint more heavily in the joints where the rust had been.

Thanks, DLM! Doesn't sound hard. Why Naptha?

We use naval jelly to get the rust off first (GREAT stuff!), then clean it off and paint with Rustoleum. Works like a charm!

We wire brushed the rusty spots and made sure the existing paint edges were feathered. Then we brushed on high gloss black Rustoleum. It's been about 4 years now and the paint job is still holding up.

We had MANY rusted iron railings to paint at our new house, so I've had lots of practice here. I think a wire brush is the best way to clean off the old rust, but do yourself a favor and get a wire brush attachment for your drill. I can't imagine using a hand brush. Make sure you wear safety glasses though--very important!

As for paint, I think a spray primer followed by spray paint will give you the best coverage with the least possibility of the rust coming back. Using a brush makes it really difficult to get into the little nooks and crannies. It's not impossible, it just requires a lot more effort.

I prefer to spray cuz I'm lazy :) But I do understand the overspray issue can be difficult and if it's not a huge area, you can easily do a brush, you just have to work a bit harder. You might look for a sash brush, which is nice for nooks and crannies...it's a round brush that comes to a point in the middle, kind of like a pencil does (if that makes sense) verses being flat or flat with an angle. If your metal is basically flat, you can easily roll it.

I always just wire brush, and if it's just a little bit by hand isn't a big deal. The sanding is to smooth out your wire work if you have to do a lot of it. If the rust isn't bad and you don't go nuts with the brush (scraping up the iron) You won't need to sand.

Primer is something I never skip. It's your long term fix, and many good primers seal well so you would be sealing the metal from future issues, but that said, rustoleum is a great paint for this type of thing and seems to hold up well. I've done metal with and without primer and while the primer jobs always hold up long term much better, the rustoleum alone holds for a few years if the initial problem you're fixing isn't a bad one.

Be sure to go beyond your rust areas about an inch or two on all sides as rust is one of those tricky things that can hide in areas near the actual "wound".

Here's more information on naval jelly (don't know where the name came from), Oceanna: http://www0.epinions.com/reviews/Naval_Jelly_Rust_Dissolver_8_Fl_Oz

It's great for getting down to the base metal before applying your primer/paint. It's cheap and easy to work with (just be sure to use gloves and put a plastic drop cloth underneath the railing so it won't ruin other surfaces).

Here is a link that might be useful: Epinions reviews of naval jelly

The Naptha cleans any residue from the metal (like if you cleaned it with something) and provides better adhesion for the paint.

Just re-read your original post - since you have peeling paint you need to wire brush back to a point that any paint remaining is stuck on but good, or you need to get down to bare metal.

Thanks everyone for the good ideas! I do have Naval Jelly. It's been raining like mad here the last few days, so we'll see if it clears up. My confidence in the rain is such that I over-seeded my lawn today. It may have to wait until spring, but then again, ya never know.