How do I polish aluminum

I have been attempting to polish an aluminum motorcycle frame and have taken the anodizing off with 220-grit sandpaper [affil link] then worked my way up to 1500 grit. Now it looks like a mirror but is very dark. It is very smooth and somewhat shiny but nothing like chrome. What should I do next? Sand more or polish? What should I polish with?

THANKS,

You said the surface is dark. That indicates 1 thing and 1 thing only to me in my experiences. Has this part been sitting for a reasonable period of time after you buffed it? The black coloration is actually the aluminum surface oxidation that occurs naturally when aluminum meets oxygen. My guess is if you got the mirror finish, you have done nothing wrong. Your next step is to take it to an anodizer, have it anodized clear (if you want it to remain that way that is, colors are an option also) and have them just quickly flash anodize the part so as to not really dull the surface. You'll retain a good majority of the shine you have now, and you'll get a reasonable amount of protection on the surface of the part to keep it looking good for some time to come.

Good luck to you,