DE-ANODISING WARNING

Do this in a very well ventilated area... the fumes are toxic!
Wear eye and skin protection.
The soda-solution on aluminum creates a gas that when mixed with air will explode if exposed to open fire!

Then just (carefully!) add the caustic soda to the water and give it a stir. Mix 125g of Caustic Soda with 1 litre of water for best results. The solution will heat up as the chemical reaction takes place. Then drop your anodised pieces in the solution.

You can see the solution doing it's stuff. The surface of the immersed bolts is 'fizzing' away the coloured anodising, and the 'waste' is floating on the surface of the solution.
After about 5 minutes, carefully remove the job from the solution - if it is ready - the surface should appear black
(dont worry - this is just the aluminium 'oxidising' you have now effectively removed its protection form the air).

Now just wash the jobs thoroughly in clean cold water, this will get rid of most of the black oxidisation.

See! - all gone now, just buff up with a bit of autosol and similar, and i've got a mirror polished alloy bolt.
Sorry about the pic quality - but it is the season to be merry eh ?

Finally - PLEASE PLEASE follow the safety instructions on the packet when fucking about with caustic soda - eye & skin protection is vital. I'll use this method myself with smaller components - but it would be pretty foolish to fill your bath up with the stuff in an attempt to de anodise your frame. Your best off taking the frame to a local anodisers and bunging one of the lads a £10 to dip it for ya.