Personally, I've never found a clear coat that truly withstands outdoor exposure form more than a year at best. Almost any coating is permeable to some degree and over time rust will form beneath the coating. Since rust molecules are four times larger that iron molecules they soon make a blister in the coating and it all goes downhill from there.

If you want the look of bare steel and want that look to last outdoors, you have to do what Hollywood does. Paint it to look like bare metal. Apply a coat of 95% zinc cold galvanizing, then a neutral primer followed by a couple coats of quality automotive acrylic enamel with urethane hardener additive. By carefully selecting your colors and the use of thin, transparent "glazes", you can create the look of bare metal. You probably won't be able to get the "brushed" look very easily, though.

For exterior work that has to withstand the elements, you are best off to use stainless steel or bronze, so you can leave them bare and they will age gracefully.

For interior work, clear coating can often hold up for some time if you use high quality paints or powder coating.

I have access to a clear that carries a 10 year guarantee.
I have had results up to 5 years no oxidation.
100% UV stable.

Out performs galvanization, powder coating, chroming or plating.
Testing to prove it.

Give me a call for details 415-517-2073

Given that no coating is perfect there are some compromise solutions used by many:

1) Penetrol
2) Permalac (no personal experience - I use Eastwood Diamond Clear)
3) Future Acrylic Floor Finish - an unorthodox but rather effective coating on steel. Do not use on brass/copper.

YMMV

crquack

Rich is pretty much right. You can however keep up a bare metal finish with maintenance though depending on the climate. If you use some sort of lacquer then top it with metal oil from sculpt nouveau you can keep reapplying the metal oil as a maintenance routine, thus ensuring the finish doesn't fail. Biggest draw back is if you don't keep it up, it takes a lot of effort to get it back the way it started.

Jake

Jake Balcom
Mettle Design
Lincoln, NE

Stephen Fitz-Gerald
Forgive me but...this is a birdbath?
Remember a good rule of thumb,"Form Follows Function",that is; all aesthetic considerations take a backseat to it's intended use.A birdbath outside with extended exposure to water and the elements should be made from non-ferrous material.As Neil Young taught us"Rust never sleeps".A silly remark I know but an effective descriptor none-the-less.Not only will the birds not like rusty water ,but it will eventually foul your pump if there is one.Stainless steel is the ideal material for such a functional piece of yard art.Not only is it stable in any weather ,but it is also easy to clean,which the birds and bees who drink from the pool will appreciate...