Pyro and Stain Fading by variation in processing steps

[Kirk Keyes]

Has anyone seen any development curve graphs (H&D graphs) for a film processed in a pyro that had variations in the processing scheme? So these things stay the same: film, developer, development time and temp, agitaion. Things that would change are: water rinse after developer vs. acid stop bath, hardening fix vs. rapid fixer (no hardener) vs. alkaline fix, alkaline afterbath (not spent developer, but say a sodium carbonate solution) vs.no afterbath, short wash time vs. long wash time?

What I want to see are how much difference any of these processing variations affect the stain. From my very few tests (acid stop vs. water bath, alkaline after bath vs. no afterbath, short wash vs. long wash), none of these things really affect the intensity of the stain very much. Graphs should also contain blue vs green densities, so we can see that the variations don;t affect the silver density (green channel), but only affect the stain (blue channel.)

I don't want to hear anectodal evidence - I want to see some comparisons with real numbers.

Kirk

[Donald Miller]

Kirk,

I don't know that anyone has done what you are asking. It sounds like a worthy project...why don't you do it?

[sanking]

"What I want to see are how much difference any of these processing variations affect the stain. From my very few tests (acid stop vs. water bath, alkaline after bath vs. no after bath, short wash vs. long wash), none of these things really affect the intensity of the stain very much."

I have tested all of these things at one time or another. Eventually I lost interest because what I found was what you have already observed, i.e. none of these factors really affect the intensity of the stain very much. They do not affect proportional image stain at all, and they affect general stain significantly only with thick emulsion films.

Bear in mind that there are two kinds of stain. There is image stain that forms around silver grains and clumps. It is formed in the presence of developer by-products and is very little affected by the type of stop bath or fixer or by the length of washing, irrespective of pH. Image stain is proportional and highly desirable.

Then there is general stain. It will increase slightly with alkaline fixers and long washing times in slightly alkaline water with certain thick emulsion films (BPF, HP5+, etc.). Best in my opinion to avoid the conditions that favor it if possible because general stain is just garbage that does nothing to enhance the printing qualities of a negative.