The other thing about Zinc Chromate is that it is _nasty_ stuff. Aircraft Spruce
are
now very reluctant to sell it to non professionals as it is a known carcinogen.
System Three's aluminium primer over alodined sufaces bonds like you wouldn't
believe!!
Tony
wrote:
> I have always used Alodine (a sort of DIY anodising) and epoxy chromate primer
> on my alloy bits. Believe me, if you want to remove the stuff you will have to
> grind it off!
>
> Alodine is not supposed to be quite as good as factory anodising but does
> score
> in two significant areas. These are:
>
> 1. The bond of the primer is crucially affected by contamination of
> the
> treated surface (one finger print is enough contamination). With Alodine, the
> treated surface can be painted within minutes of treatment, thus minimising
> the
> opportunity for comtamination. Unless parts returned from the anodisers are
> thoroughly redegreased, there is a good chance that bond strength will be
> adversely affected.
>
> 2. Anodised surfaces will slowly hydrate which reduces the strength of
> the subsequently applied bond . Boeing have developed a proprietry technique
> (involving the use of phosphoric acid) which inhibits this and allows longer
> storage of parts before use.
>
> As our noble leader says, "cleanliness is next to Godliness".
>
> All IMHO of course.
>
> Rgds Duncan McFadyean
>
>
---------------End of Original Message-----------------
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Date: 01/03/97
Time: 09:40:02 New Zealand Summer Time (UTC +13)
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