I've found that some Al alloys will stay bright polished for quite a long time (polished Campy cranks and brake calipers which appear to me to be made of the same alloy), while others such as the alloy used for the hubs or the non-anodized FD will not. Cinelli stems hold a bright polish pretty well too.
The engraved or stamped markings will generally survive a careful polishing if there are no deep gouges through the marked areas. The old Cinelli-Milano stamping on the top of the stem quill is often too lightly impressed to survive a repolish, but most Campy stampings come through just fine.
It's hard, even dangerous, work refinishing these old components at times. Wear eye protection for sure while using a buffing wheel! A full catcher's pads and mask might even be in order.
I'd like to try my hand at reanodizing some parts. There's a lot of material out there that is in wonderful functional shape, but is unfortunately marred by a scrape or two that could be brought back to almost unused (or even better, frequently) appearance with a little careful attention.
Kurt Sperry in,
Bellingham WA