Classic & Vintage - Aluminum finishes - silver anodized vs. polished

I'm wondering if there is a difference between silver (clear) anodized aluminum, and polished aluminum. Is a part that is sold as 'polished' going to be the same that one manually polishes, or does one have to anodize it as well to prevent corrosion?

Posting here because it seems like most modern components are painted black for some reason, but a lot of vintage parts are polished (or anodized?)

Anodized and polished is the upscale treatment found on higher end components like Campy brakes and cranksets. It requires no more maintenance then cleaning with soap and water. Polished aluminum looks good for years in a row but oxidation will give it a milky dull appearance that can be corrected by polishing yourself with Simichrome and a rag, a Dremel tool, or a bench grinder with polishing wheels and polishing compound. The serious C&V enthusiast with a little time on his hands and a herd of old bikes can really have some fun with the bench grinder. It should be set up on a portable stand that you can take outside and you'll want to wear old clothes because you and your surrounding area are going to be covered with a combination of aluminum and polishing compound. At some point a part is going to get away from you and get launched in some direction so your set up should have a back board and you might not want to operate near windows or really tall grass.

Modern parts are black because it costs less and marketing has advertised the black look enough so that novice buyers think it looks good. Some aluminum components are anodized black but they still look like poo once they get scratched up.

So polished aluminum will eventually get that dull grey oxidzed look, but anodized aluminum will not?

Correct.

Non-anodized before polish:

http://photos.thecuda.com/upload/components/tn_P3152168.JPG

After polish:

http://photos.thecuda.com/upload/components/tn_P3152175.JPG

Sleeve area is polished, bars are a satin anodizing:

http://photos.thecuda.com/upload/serotta/tn_P3092096.JPG

Ah, cool. How old is that seatpost? How long before it started looking tarnished?

Post is a late 80's, early 90's campagnolo post. The time it takes for a polish to dull depends partially on the polish used (many have a wax to protect the finish, but not what I'd recommend using on braking surfaces!) and the weather at the location. Haven't been in the scene long enough to really know how long it lasts here in Dallas, but I foresee a full polish job being a once a year thing for me. :)

keep in mind though, that subsequent polishes won't be as intensive as the intial restoration. A rag and some sort of compound (simichrome, mothers), will usually get it back on track. It more of a matter of consistency.