On 10 May 2006 10:19:36 +0200, Chris Bacon wrote:

The Natural Philosopher wrote:
Ive had best success with stuff like 'jenolite' which IIRC turns iron
oxide into iron chromate

Iron phosphate, isn't it?

Phosphides and tannates. At least you get tannates if you use the good
stuff (usually white) rather than Jenolite or plain phosphoric acid.

Not bad as a preparation of existing rust you can't remove, but it has
limited resistance to rusting in the future. In particular it doesn't
have the electrolytic protection that zinc coating (plate or paint)
offers.

Chromates are useful for aluminium (the yellow-green stuff) but they're
horribly toxic.