Hi FH, since you're using it inside you could probably use regular mild steel. Both materials are clean when you get them and will have to be aged/patinaed. Corten is usually used because of the elements tendency to keep eroding the steel away, but there really is no chance for this to happen inside. The temp and humidity are probably both controlled. The rust will wipe off both just as easy, so some sort of flat or satin clear coat would probably be best. Since it's inside and the look is rusty the brand probably isn't too important, but at least use a brand you trust. I wouldn't recommend a clear powder coat because rust has a tendency to gas out causing air bubbles in the finish. It would save a bit of money to use mild steel and probably be much easier to obtain. I've gotten Corten from Central Steel in Chicago and some place in Arkansas. I had a much better experience with Central Steel and they were very helpful. I think Kyle Fenwick was the name of the guy who helped me there.

Jake

I'd have to agree with Jake on this. My advise would be to use mild steel and save a bunch of money to use somewhere else. Cor-Ten is used for it's rusting qualities in the outside. To pay the extra money for it and then use it inside would be a waste. And, you are correct on the rust getting on everything that came in contact with it.

Rick Crawford at Smoky Forge

I'm with jake and Rick - forget the CorTen, it's not necessary. Use mild steel.

If you want the appearance of rust without the hassle of smearing, dusting, flaking, etc, why not just just simplify the whole issue and paint it to look like rust? Very easy to do, and won't deteriorate like a clear coat with rust beneath it may do. Sandblast the steel, spray with 90% zinc cold-galvanizing, then prime with red-oxide primer and topcoat with two or three coats of acrylic enamel automotive color mixed up to look like rust. With a bit of careful work with a detail gun and some highlight colors, you can achieve a finish that is absolutely indistinguishable from bare rust but is perfectly stable.

mild steel,
clean with strong alkiline soap to degrease
sandblast will also degrease and clean off black oxides so you are ready for rust.
acid etch,
oxidize: peroxide from the drug store with a few drops of acid and a dash of table salt works wonders.

neutralize with baking soda,
rinse

I have good luck sealing indoor pieces with acrylic floor finish.

Gene Olson
Sculptor
Elk River, MN

Thank you all for the helpful suggestions. The information is great and gives us new avenues to explore on this project.
FH