Use silvo or something to polish and then leave it alone. Alluminium oxidises extremely quickly when polshed so the only way to keep it looking polished is to coat it. If you leave it alone it will get the standard aluminium finish on it pretty quickly. The grey finish you have now will be a result of the chemical soaking you just gave it.

In other words if you want it to look like a standard SU, polish it, buff it off and then leave it alone. Hope this helps.

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Cheers
Alec
1275LS - July 78 - XNFAD18Y/102918