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In article ,
(Huge) writes:
Chris Bacon writes:

Hm. Yet there's plenty of polished aluminium about. How *do* they
do it ?

You're looking at a coat of aluminium oxide.

Aluminium oxide is transparent -- clear as glass.
It's also incredibly hard (not far off diamonds), although
the layer which forms is really too thin to provide much
protection. It can be deliberately thickened by anodising,
which makes the surface harder. It's a damn good electrical
insulator too, which is a bad thing when trying to connect
aluminium conductors.

--
Andrew Gabriel