[pure-silver] Re: Adding Sodium Sulfite to Sodium Thiosulfate.
- From: Jean-David Beyer <jeandavid8@xxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 05 Apr 2011 06:56:16 -0400
BOB KISS wrote:
> DEAR MICHAEL,
> I seem to recall (so I checked my Adams book) that his formula for
> Amidol developer did not contain any alkaline salt accelerators (Sodium
> carbonate, Borax, etc) which lowered the pH except Sodium Sulfite which
> acted more as a preservative than an alkaline agent. So acid stop bath is
> not much more effective in stopping Amidol developer than water because
> there is no alkaline accelerator to neutralize...which is how stop bath
> works with standard, higher pH developers.
> I say this under correction by those with more knowledge than I
> (Eric Neilsen, Mike Ware, etc) but I think it is so.
> CHEERS!
> BOB
>
Actually, the sodium sulfite in typical formulations of amidol
developers provides the alkalinity required. Development occurs with pH
greater than 3 all the way up to 14, but fog goes up with increasing
alkalinity, and I believe oxidation does too. I put about 5 to 10grams
of citric acid in my amidol developers. When the pH gets down to 3,
activity stops. I do not remember offhand what the pH of SB-1 stop bath
is, but that is what I use with paper developed in an amidol developer.
It is cheap and I replace it frequently.
--
.~. Jean-David Beyer Registered Linux User 85642.
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