Anodising...whats that all about?

It does scratch quite easily. Bolts, and things that don't take a lot of abuse, should be OK. But things like a heel plate should be "powder coated".

You can only anodise aluminium, the Acid used in the process would eat steel. You use Lead as the -VE connection & the item you want anodised is the +VE connection. Then you pass a current through the tank, which will form a clear, but porous layer, on the aluminium being anodised. After this process you can then dye the item in a heated tank of dye, before the final process of sealing in steam / boiling water.

You can specify a hard anodize which is extremely wear and scratch resistant. In the US, you would give this specification to the plater: HARD ANODIZE PER MIL-A-8625F, TYPE III, CL 1 if you want a "clear" anodised surface. This means that no dyes are used to change the color. A hard clear anodised surface ends up being a very dark bronzey grey, kinda like the color of the anthracite SuperDukes. Actually, that's for 6061 aluminium. Different grades of aluminium will turn other shades of dark grey. If you want the parts to be black, then specify HARD BLACK ANODIZE PER MIL-A-8625F, TYPE III, CL 2. That will be as black as black gets and it won't scratch off.

Oh, if you decide to spec the hard anodizing, also tell the plater to "mask all threads and bearing surfaces" (you should probably indicate which surfaces you want masked). Otherwise it'll be a serious bitch getting screws and bearings back into the part. Anodizing grows a ceramic layer on the surface. It's only a couple thousands of an inch thick, but that's at least ten times greater than the tolerances on bearing fits and it's enough to keep screws from getting in and getting a tap to grind through the ceramic coating is really difficult.

FYI

http://www.secondchancegarage.com/public/665.cfm

http://www.focuser.com/atm/anodize/anodize99.html