Hi,

Given that Amidol developers oxidise rapidly, I was wondering if it would be wastefull to process prints in a rotory processor with an amidol developer. I suspect that rotory processing oxidise the developer more quickly than tray processing because when using a Jobo you tip the fluid in, process, then tip it out. Thus the developer is getting a fair bit of agitation.

-- Philip Caithness (pcnexus@ozemail.com.au), December 21, 2000

Answers

I believe Amidol developers could be used effectively in rotary processors with the addition of a little citric acid to prevent oxidation. Weston typically added 5 to 10 grams of citric acid per liter to his favorite Amidol formula, and Samuel Fein has a formula that includes 13.5 grams of citric acid per liter. See "Investigations of B&W Exhibition Papers," Darkroom and Creative Camera Techniques, Vol. 6, No. 1 (Jan./Feb. 1985). Amidol is the only developing agent that can maintain its effectiveness in a slightly acetic environment. Sometimes lactic acid is also used for this purpose. I have a number of amidol formulas on my site:

http://unblinkingeye.com/Articles/Developers/Formulas/formulas.htm

-- Ed Buffaloe (edb@unblinkingeye.com), December 22, 2000.