Thought I'd share something, as it's actually something to do with restoring bikes that I am reasonably good at! I don't have anywhere I can use a buffer so had to try to learn to do a good job by hand...
Make sure you get as fine a grade of wire wool as you can. I find the DIY store stuff isn't all that great. Depends what you are after in terms of finish I guess. I tend not to use it at all.
I've successfully used wet and dry sandpaper for alloy parts. Again a very, very fine grit. I wouldn't drop below 1200, unless you are not too bothered about removing a lot of the item's surface. Working up to a super fine one, 2500 - 3000. Be methodical by working across the piece all in one direction, and then the other direction. Keep moving as well so you don't over sand one area. I then polish with Simichrome paste, but I imagine it's much the same as Autosol and all the other bits.
I'd say it's mainly then about patience. A couple of hours plus, off an on, went in to the stem below. It takes ages if you want a superb finish, and is really boring. It's also filthy! And if you value the part a lot, practice on something else first. Also be careful not to overwork the item if it is a seatpost or stem or something that has a very fine tolerance in terms of fit. You don't want to go from a 27.2 to 27.0 seatpost by being overly vigorous. Sometimes a bad finish means a working part! Or if possible, just leave any insertion section unpolished. Oh, and watch out for if the part is anodised or not. You need to either make sure you don't take any anodising off, or decide to take it all off. Getting anodising off is another story!
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