[alt-photo] Re: Clerc and am fe citrate

[Don Sweet]

Thanks Peter for that guidance.  I have tried a test:

First I put about a teaspoon of the khaki FAC into about a tablespoon of
water, and it turned a russet colour.  Then I splashed some of the russet
solution on a paper towel (A) and dripped some pot fer solution into that
puddle.  After a night in the dark the centre of the puddle was prussian
blue.

Next I mixed about a quarter of a teaspoon of citric acid into the russet
solution.  After a few hours the solution was a clear apple green colour. I
splashed some of the green solution onto 2 different paper towels and
dripped some pot fer solution into those puddles.  I left one (B) in the sun
and in a few hours it looked just about the same as A, maybe a little closer
to ultramarine.  The other (C) I left in the dark overnight, and in  the
morning it was near enough to cyan in the middle.

Obviously dosing the khaki FAC with citric acid has achieved something, but
I am not sure what that is.

Don Sweet


----- 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: Friday, March 09, 2012 3:53 PM
Subject: [alt-photo] Re: Clerc and am fe citrate


> Hi Don,
>
> The green variety of ferric ammonium citrate is a somewhat muted
> green (camouflage green!) either in solution or as dried scales or
> powder so it seems that your green fac must have deteriorated. If
> this is the case I suspect it is many years old or was exposed to
> light, heat. I have some three year old solution which remains a nice
> shade of green and tests free of any ferrous species. A little
> potassium ferricyanide makes for a simple test for this reduced form
> of iron. If the test is negative, then perhaps you do have the brown
> form. I heard mention once that a wee bit of hydrogen peroxide can
> re-oxidize ferrous but I have not tried this.
>
> As far as attempting to change the brown variety to green? I made
> some attempts along these lines but was not successful. You see, In
> my first attempts to make green fac, I was always ending up with the
> slower brown variety. I then attempted to adjust the quantities of
> citrate and ammonia but it remained brown. I even left this for days
> hoping it would re-speciate, but to no avail. Changing the order of
> addition allowed me to produce the green variety.
>
> Perhaps you will have better luck with conversion. Keep us posted.
>
> Peter Friedrichsen
>
> At 03:19 PM 06/03/2012, you wrote:
> >Peter
> >
> >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
> >
> >Don Sweet
> >
> >
> >----- 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
> >
> >
> > > Alberto,
> > >
> > > 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.
> > > From:
> > >
>
>http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfCFR/CFRSearch.cfm?fr=18
4.1296
> > >
> > > 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?
> > > >Alberto
> > > >www.grupponamias.com
> > > >www.alternativephotography.com/wp/photographers/rodolfo-namias-group
> > > >_______________________________________________
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