[alt-photo] Re: Clerc and am fe citrate
don at sweetlegal.co.nz
Tue Mar 6 20:19:28 GMT 2012
A couple of years ago you helpfully presented a method of making ferric
ammonium citrate (green) starting from ferric chloride. I have been
thinking of trying it, as all my fac (bought as "green" from reputable
sources, but in some cases now a little old) is actually a dark khaki
colour. Is that still "green" fac, or has it deteriorated at some point?
On a related topic, I have read that brown fac can be converted to green by
the addition of about 20% citric acid. Is that right?
Thanks for your help
----- Original Message -----
From: "Peter Friedrichsen" <pfriedrichsen at sympatico.ca>
To: "The alternative photographic processes mailing list"
<alt-photo-process-list at lists.altphotolist.org>
Sent: Tuesday, March 06, 2012 11:09 AM
Subject: [alt-photo] Re: Clerc and am fe citrate
> I found this description some time ago. It doesn't tell you that the
> green and brown forms depend not only on the composition, but also
> how the starting chemicals are combined.
> (1) Ferric ammonium citrate (iron (III) ammonium citrate, CAS Reg.
> No. 1332-98-5) is a complex salt of undetermined structure composed
> of 16.5 to 18.5 percent iron, approximately 9 percent ammonia, and 65
> percent citric acid and occurs as reddish brown or garnet red scales
> or granules or as a brownish-yellowish powder.
> Peter Friedrichsen
> At 03:03 AM 04/03/2012, you wrote:
> >I am looking for the chemical definition brown ammonium ferric
> >citrate given by Clerc. I remember a footnote in:
> >Clerc, L.P. (1950) "La Technique Photographique"
> >5th Ed, tome II, Publications photographiques et cinematographiques
> >Paul Montel, Paris V, 1950, pp.816-817
> >I have had the oppportunity of taking some notes about the empirical
> >formula of the green form, but unfortunately I did not save the
> >information about the brown one.
> >Now I nave not the opportunity to look at Clerc anymore. May you help me?
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