A matte spray varnish works......
I know a dealer who sprays all her old metal stuff with Pam!...Doesn't last long.......but it shines them up good!....and is easy to remove if you don't like that look.
Also rubbing with minwax antique oil finish will seal it without much gloss.
Linda C

I think I'd take a wire brush and get as much of the rust off as possible. Other options would be naval jelly or if you have someone that does sand or bead blasting nearby, then get them to get the "crud" off. If you leave the rust on them...it's like an unchecked disease, it will keep on growing. Once cleaned, use a primer (like Rustoleum) and finish coat of your chosen paint. I also use the varnish spray that Linda mentioned for my outdoor pieces.

You could also ask this question over at the Garden Web Garden Junk board. I'm sure I saw a thread about this a while ago.

I have a large walkin fireplace in my dining room . We have a lot antiques sitting around it That would have been used. when I fall clean and spring clean I go over the cast iron pots,pans coffee pots etc with liquid gold they stay nice. Youre suppose to use it on paneling but I found it shines up brass,copper and its good for this too.