[pure-silver] Re: I say Ammonium you say Potassium
- From: Eric Nelson <emanmb@xxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 21 Aug 2007 18:19:43 -0700 (PDT)
Thanks Richard!
Blumann's book here is circa 1937 and my edition of
Anchell's Cookbook is from 1994 so over a wide spread
of time nothing changed in my references...although I
wasn't around for Blumann haha!
Too bad for me no one made any published notice of the
ability to substitute Pot. for Amm. that I could
easily find.
Eric
--- Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
>
> ----- Original Message -----
> From: "Eric Nelson" <emanmb@xxxxxxxxx>
> To: <pure-silver@xxxxxxxxxxxxx>
> Sent: Tuesday, August 21, 2007 11:16 AM
> Subject: [pure-silver] Re: I say Ammonium you say
> Potassium
>
>
> >
>
> More research: Kodak did indeed change the
> formula! My
> source for the formulas with Ammonium Persulfate are
> the
> patent and the Kodak and Agfa/Ansco versions as
> published in
> the _Photo-Lab-Index_, 1944 Navy edition. This
> version is
> also printed in the 1943 edition of the _Kodak
> Reference
> Handbook_. However, in the processing section of the
> _Kodak
> Reference Handbook_, 1946 edition I find that the
> formulas
> for both T-21 (Nelson's Gold) and reducer R-5
> specify
> Potassium Persulfate. The same formula is found in
> the 1953
> reprinting of the 1947 (third) edition of
> _Processing and
> Formulas_ in the Handbook.
> All of these include the instruction to refix
> the prints
> after toning but this was left out of one of the
> editions of
> the _Processing and Formulas_ booklet with a note
> added that
> the results of Nelson's were not as permanent as
> other Sepia
> toners. Of course it wouldn't be if it left halides
> in the
> emulsion and they were not fixed and washed out.
> This error
> occurs in AFAIK only one edition of the booklet.
> The amounts given for the Potassium salt are
> identical
> to those given for the Ammonium salt, which is, of
> course,
> the anwser to the question: either may be used
> interchangibly. This is also true for the Persulfate
>
> reducer, Kodak R-5 where formulas showing both salts
> are
> shown with the amounts identical.
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
>
>
>
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