I'm no metallurgist, but I DID stay in a Holiday Inn last night:
Oxidation - anodization. It's just about the same thing, really.
Metallurigicly (sp?), aluminum is a passive metal. Left to the air, it will get a thin coating of oxidation that will go so far and will stop unlike on an active metal, such as iron, where the oxidation will continue and will eventually eat all the way through. This surface catng can also be artifically (chemically) induced by anodizaion which also serves to seal the alumimun from the air and the further effects of natural oxidation (produces a barrier).
So to answer your question, the parts that look dull - reall dull - are probably not anodized. Problem is, this is just about what clear (silver) annodizing looks like, so they can be hard to tell apart. You definately don't want to put the elbow grease on 200 when polishing these, because in the process you'll strip through the anodizing you may wished to salvage.
There is a 2 second test for determining if a part is anodized. Simichrome will assist to strip away oxidation. It wil have no effect on anodized parts that windex won't have (wipe off surface film). Get a rag with a touch of simichrome on it. Rub it on the part in question, just for second. Look at the rag. If it has black on it, the part is not anodized. If is doesn't, it is.
> I'm in the process of building up a Merckx with NR/SR parts. I needed to
> know if anybody has any tips on how to polish the stuff up and which parts
> can and can't be polished. I took to the flanges of my SR hubs with my
> dremel and simichrome polish and it seemed to work well. Buffed up a nice
> shine to it.
> I reckon the black or anodized parts can't be polished, but which ones are
> those? I usually can tell with new stuff, but with older stuff, I have a
> bit of a harder time telling the difference between silver anodized and just
> plain aluminum.
> BTW, should I take apart the wheels before polishing?