----- Original Message -----
From: <Camclicker@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, September 02, 2005 8:19 AM
Subject: [pure-silver] POTASSIUM -Vs- SODIUM...
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....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
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