Originally Posted by
Nessism
No anodizing? That's odd. The stem will tarnish quickly without some sort of protection, or constant attention to cleaning.
As for how to polish, there are countless guides on the internet and youtube to guide you. In a nutshell, start out with the least abrasive means possible to remove the imperfections you find unacceptable and then progressively move to less and less abrasive means until you have the desired sheen. If you have a power buffer or a decent bench grinder you can employ a wheel and compound to save time. A stitched cotton wheel is likely all you need, along with some compound bars. If you are in the USA you might want to hit up Harbor Freight for supplies.
After finishing the metal will need some sort of protection otherwise it will tarnish very quickly. Wizards Power Seal is one such product. You will still need to keep on top of the polish but this will at least afford some level of protection.
I removed the matt black finish on exposed portion of this Truvativ seatpost using fine sandpaper, emery cloth, and then Simichrome polish. Surprised how easy and quick it was. No additional protective material. i expected that there would be tarnishing, but there’s been minimal degradation of the polish level in three years.
Before:
After: