Thanks guys,

Sounds like great advice. 

I live about 15km from the ocean but it's surprising how fast things rust around here.  I tumbled some coach bolts that had a little rust on the cup heads as an experiment a couple of months ago. Whilst they looked great when they came out the tumbler, they are already rusty again so I'm going to have to be careful about rust protection.

I think my method will need to go something like:

1) kill any rust with ranex
2) clean up & polish
3) protect with al & li spray or paint with rust guard type product for coloured finish.

I did see some silver coloured zinc 'cold gal' spray in a hardware store and was wondering about that so it's good to hear about something that people have actually used, works and looks good.