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May 2001

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From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 18 May 2001 09:26:24 +0300
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Doug

Citric acid is a funny one. It is tribasic (compared with dibasic for
most of the other usual N/C activators). Hughes are not the only one to
come unstuck with citric: Zeva had a citric acid/glycerol (a triol or
tribasic alcohol) W/S flux in the 1970s, long before Hughes. I believe
that the problem with citric is that it forms unstable chelates with
some heavy metals (don't drink lemonades etc. from lead crystal or
lead-containing pewter vessels!). The later formulations were, I
believe, with maleic acid (found in green apples), which is dibasic. Its
ages since I heard anything about HF fluxes: I thought they had died a
natural death.

I had a really bumper crop of lemons this winter, so my personal citric
to maleic ratio has increased enormously :-)

Brian

Douglas Pauls wrote:
>
> Very interesting, Jim. Do you happen to know who made the HF series of
> fluxes? I would like to get data sheets on them.
>
> The original HF1189 was based on citric acid (lemon juice) as the
> activator.  The HF stood for Hughes Flux.  When it first came out, it was
> hailed as the greatest thing since sliced bread.  A classic case of a
> marketing department gone amuck.  The citric acid can be corrosive and
> there were some memorable military failures as a result.  Several studies
> were done on the 1189.
>
> I believe Kester picked up the 1189 family.  They reformulated the
> activator away from citric acid toward more benign weak organic acids and
> called it HF1189A.  If I recall, the 1189A contains no citric acid.
>
> I suggest you contact Kester for more information.
>
> Doug Pauls
> Rockwell Collins
>
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