John Schmitt wrote:

With anodised aluminium, it is a synthetic dye adsorbed onto the
surface that gives it the colour, effectively a lake. (q.v.)
Anodised titanium works on film thickness, but is fairly
complicated to achieve a predictable colour without a lot of
(expensive) trial and error. Current, duration, electrolyte and
so on all have an influence. Had I realised this was the path you
were going down, I'd have suggested (DIY ideals notwithstanding)
that you buy the stuff ready coloured.


Hi John,

You are always a mine of information for exotic processes !

I do have the tackle to play with the anodising process, for Ti, it
takes quite a high voltage, and you need to pickle the metal before
treatment - the preferred pickle until recently contained HF acid, but
that has been dispensed with. Repeatibility isn't really an issue.

I have finally found a Ti supplier in the USA that supplies what I want
for around 12p / sq. in, as opposed to the £5.00 sq in I have been
quoted here. www.reactivemetals.com for interest.

Steve