Using a drill with a wire brush attachment would work for this. Just be sure you wear eye protection.

There are all shapes and abrasive grits with these drill brushes, so depending upon how rusty the metal is will determine how aggressive you want to be when selecting the attachment for the drill.

If you have a lot of detail, you can either rent a small portable sand blaster or hire someone ...»

E.C. P - I'm not knowledgeble like Woodbridge. I can only tell you what I am trying out. It is called Gempler's rust converter. They say it converts rusty iron to an invert black protective barrier that you can paint. I have already applied it to a number of rusty areas & I am going to see what it does next.

Oh I forgot to tell you to use a sponge applicator if you try this. The decorative item I'm doing is very hard to work with.

If the wire brush did not work, you need to sand blast the metal, Soda blasting also works as well. Look in yellow pages for this type of contractor.

The rust converter from my understanding coats the oxidation on the metal, It will do nothing to smooth out the surface of the existing metal. This product has its benefits but not for something exposed to the weather as the iron railing is.

I have to agree with woodbridge that a "paint" type product with only get you half way there. even with sand blasting the metal may not be entirely smooth.

Woodbridge & KMS I won't disagree with anything either of you write but I want to tell you that the rust converter product I used did a beautiful job on rusty iron. I only had to lightly sand it. It is a primer so I painted it after that. Will it last? I don't know but it sure looks good now. Try it.

Perhaps its the type of metal you used that product on. But like cancer you must remove the rust completely or it will come back. Particularly on wrought iron and steel railings. The metal used to make these fixtures tends to de-laminate as it rusts causing the material to swell as the rust takes over. But in any case, I am glad what you used worked. There is products made all the time us old folks just do not trust like good ol elbow grease. Perhaps you just found one that does!

This also depends on the "level" of rust... a simple red tint of the surface may very well last a long time using that product. While "blister type" thick scabs of rust will fail much much sooner. Rust is a by product of moisture and Oxygen reacting chemically with the iron. Paint jobs attempt to prevent these reactions from occurring, by physically blocking them. In the case of thick scabs or blisters of rust the air and moisture will still be present "below" the bubbles of reacted ...»

I only completed one small item to see if it worked and it did. I have one very large trellis that I saved for last because of the size. The product works on iron and steel so I don't have to guess what it is.

Want to see a picture of rust before I fix it? It doesn't have thick scabs but it does have little bubbles and orange color in many places.

We do this at my company and you can blast it, or brush it but you don't have to do that. A moderate wire brushing by hand and two or three coats of rust converter and then a couple of coats of primer over that with a couple of coats of paint a viola you are good for a very long time with very little effort and mess. Sand blasting comes with many evils of its own and if you are not familiar with that or are not going to hire a professional I would suggest that you steer clear of sand ...»