Retail primer for diecast aluminium?

I have two outside lights made from diecast aluminium/zinc (aka Mazac) where the paint has come off in big flakes because the primer (in any) has not adhered to the metal. I have used a bead blaster at work to clean off the white powdery surface back to bare metal. Please can anyone point me to a source of etch primer that I can use to get a good key into the metal surface. Ideally this would be brush or aerosol applied.
I only need small quantities so a retail source would be ideal.
TIA
Bob Minchin
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Bob Minchin wrote:

Try Halfords...I THINK they do a metal etch primer.

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Knew I'd seen it somewhere . . . . .
http://www.decoratingdirect.co.uk/ but single pack it 27quid for 5l :-!
A quick google reveals many sources of 500ml tins, but mainly fancy stuff from International & the like at 16quid.
I notice from a technical sheet on it that it uses phosphoric acid as the etching agent, the same as is found in Jenolite rust treatment, could that be a cheap alternative to the real stuff?
--
fred

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Marmite is made with caustic soda, but I don't suggest spreading that on your toast.
-- Smert' spamionam
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It's the etch we're after init, does it matter which source of phosphoric acid we use for it :-?
ps: I'd rather gargle with the latter than have the former anywhere near me toast :-0
--
fred

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So it's the same acid as used for etching steel?
--
*One of us is thinking about sex... OK, it's me.

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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