Sandy King (sanking@hubcap.clemson.edu)
Sun, 23 May 1999 12:43:47 -0400
The Film Developing Cookbook contains a working formula for 1 liter (p. 59)
and a concentrate formula for stock solutions. (p. 127). The stock solution
formula in the FDC is apparently different from the original Crawley
formula, which was much more concentrated (see earlier message from Richard
Knoppow). And a slightly different version of the formula was given by
Anchell in Camera and Darkroom (July 1995).
Sandy King
>Is the FX-2 formula in the Film Development Cookbook a concentrate? I
>thought it was a working solution. Also, I don't believe any developing
>times were given in that book for FX2 with Tri-X or T-Max 400. Does anyone
>have any suggestions?
>-----Original Message-----
>From: Richard Knoppow <dickburk@ix.netcom.com>
>To: alt-photo-process-l@sask.usask.ca <alt-photo-process-l@sask.usask.ca>
>Date: Sunday, May 23, 1999 3:59 AM
>Subject: Re: Question about FX-2
>
>
>>At 03:30 PM 5/21/99 -0500, you wrote:
>>>Does any one on the list use Crawley FX-2 developer? If so I would
>>>appreciate your comments about its qualities.
>>>
>>>In The Film Developer Cookbook the directions to mix FX-2 call for the use
>>>of potassium carbonate crystals, not anhydrous (the crystal form is said
>to
>>>give a slight bicarbonate buffer effect). What does this mean, and how
>>>might the same effect be gotten with the anhydrous variety?
>>>
>>>Sandy King
>>>
>> The original FX-2 formula is for a highly concentrated stock solution and
>>I think the preference for both the Potassium salt and the crystaline form
>>stem from their greater soluability.
>> In a developer the carbonate slowly hydrolizes to produce both the
>>hydroxide, which is the actual accellerator, and bicarbonate. Because of
>>the large resevoir of hydroxide in the carbonate it act as a good buffer
>>and the pH of the solution tends to remain constant
>> Sodium carbonate is usually preferred over the potassium salt because it
>>is not delequescent. Potassium carbonate is very delequescent so must be
>>stored very carefully to prevent moisture absorption and consequent loss of
>>strength.
>> Again it is this very quality which makes potassium crystals desirable
>>for highly concentrated developers like FX-2.
>>----
>>Richard Knoppow
>>Los Angeles,Ca.
>>dickburk@ix.netcom.com
>>
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