[pure-silver] Re: POTASSIUM -Vs- SODIUM...
- From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 2 Sep 2005 12:06:06 -0400
>> The "Calls For, You Got" section of the Cookbook suggests
>> Sodium Carbonate
>> can be used in place of Potassium by using 1.12 time the
>> amount of Potassium.
I experimented with replacing the sodium carbonate in the Beutler
formula with potassium carbonate. I found that I had to *decrease* the
amount of potassium carbonate relative to sodium carbonate rather than
increase it.
My suggestion would be that unless you want to do some experimenting
with a particular formula that you stick with the carbonate specified
and not try to substitute.
Jerry
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Knoppow
Sent: Friday, September 02, 2005 11:26 AM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: POTASSIUM -Vs- SODIUM...
----- Original Message -----
From: <Camclicker@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, September 02, 2005 8:19 AM
Subject: [pure-silver] POTASSIUM -Vs- SODIUM...
> ...CARBONATE
>
> The formula for Pyrocat HD that I have calls for 75 g
> Potassium Carbonate in
> Part B.
>
> The "Calls For, You Got" section of the Cookbook suggests
> Sodium Carbonate
> can be used in place of Potassium by using 1.12 time the
> amount of Potassium.
>
> I don't question this to be true but there must be a
> difference in the final
> product -- no? If you don't use Potassium won't you loose
> something or gain
> something you probably don't want? Or are the results
> interpreted as equal?
>
>
> Bruce
> Brooklyn, NY
> camclicker@xxxxxxx
> www.camclicker.com
>
Supposedly, potassium salts are slightly more active in
photographic solutions than sodium but this is somewhat
controversial. Generally anhydrous sodium carbonate can be
interchanged weight for weight with potassium carbonate.
Potassium salts are common in Agfa formula because they made
their own as a by-product of something, and got it cheap.
Potassium carbonate and Potassium hydroxide can be dissolved
to a higher concentration than sodium salts so are popular
for highly concentrated solutions (like Rodinal). However
Potassium carbonate is desiquescent and not as stable as
sodium carbonate in storage. Kodak used to recommend
potassium carbonate for motion picture labs beause any that
got into the air would stick to whatever it landed on
instead of continuing to blow around.
Supposedly warm tone paper developers are slightly warmer
when mixed with Potassium salts. I've seen no actual
evidence of this.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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