Join Date: Aug 2010
Bikes: 1954 Raleigh Sports 1974 Raleigh Competition 1969 Raleigh Twenty 1964 Raleigh LTD-3
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After removing the pad residue with solvent I would start with simple rubbing compound
available at any auto store. It looks like the scratches are not that deep and sandpaper is probably not necessary. If the rubbing compound is not enough to get it smooth I'd go with 1000-grit wet-sand paper first with a pinch of dish soap in with the water. Alloy is really soft and it doesn't take much to dig in. If the 1000 was not getting the grooves out I would drop down to 600-grit wet-sand paper (with some soap) and smooth very carefully before working my way back up to 1000 and then rubbing compound -each step finer to remove the scratches made by the previous step until they are all gone with the rubbing compound.
Finish up with polishing compound
and then mother's to seal it back up or the alloy will darken and gray out as it oxidizes again if exposed to air. Aluminum oxidizes if not protected by a clear coat, anodizing, or some form of wax to protect it from the air. Fortunately this thin surface oxidation actually seals and protects the alloy from any further oxidation unlike steel which keeps rusting/oxidizing. But alloy DOES oxidize on the surface if it is not treated/protected and will be a dull gray color eventually. Saltwater is even worse for bare aluminum and can cause nasty pitting if allowed to sit over time.
Do this polishing/sanding by hand or use a Dremel tool with a cloth wheel for the rubbing and polishing steps if you want to go faster. But do the sanding by hand with a LIGHT touch as it is easy to go too fast.
You should end up with a beautiful polish that looks nice. Even without the anodizing it can be made to look almost as shiny as chrome and if Mother's alloy rim polish is used on it the finish will stay shiny for a long time.