Polishing aluminium frame ?


Senior Member
Any tips on how to mirror polish an aluminium MTB frame ?

I have a GT frame already stripped but not polished, and a couple of others that need stripping as well.
Loch side.
Simply strip the paint and polish with an abrasive polish such as Brasso or fancier commercial buffing compound.
You'll get a mirror finish, but it won't last. Aluminium quickly oxidises (and passivates) to a duller colour. To retain a mirror finish you'll have to apply clear lacquer (very quickly) or anodise it.

Keep in mind that some high-end frames are bead-blasted just before painting and should never be sandpapered. This destroys the compressive "skin" created by the bead blasting which strengthens the frame and guards against fatigue.


Legendary Member
Cannondales have a lot of extrusion marks under the paint. It looks ok polished but to get to a true mirror finish would involve removing a lot of metal. Lacquer afterwards to prevent it going crusty from sweat/road salt.
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