View Full Version : Chemical Reaction with Pyrocat & D-76?

Jeff Dyck
1-Nov-2005, 14:42
Last night I was developing some sheet film and had a very strange occurance. I have been developing all my sheet film (generally TMY, PL100 and FP4+) with Pyrocat-HD and Formulary TF4 Fix in Jobo Expert drums for the last couple years with excellent results. I had some old Tri-X in the freezer that I wanted to use up, so shot some of it on my last outing. I have had less than ideal success in the past with the Tri-X / Pyrocat-HD combination, so decided to develop the film in Formulary TD16 ("Improved D-76") diluted 1:1 in the Expert drums. After processing the film, I opened the drum to remove the film for additional washing and could tell immediatley that something was wrong - the emulsion of the film was super soft, the emulsion surface felt slimmy like a fish and the grain was HUGE - the negative looks "pebbled" to the naked eye. TF4 contains no hardener, which might partialliy explain things, but I have never experienced an emulsion this soft (the clothes pins used to hang the film for drying literally squished the emulsion out like an overfilled grill cheese sandwhich!), and I have no explaination for the massive grain (the degree of development itself looks fine - nice range of tones). I thought there may have been some type of interaction with some reminants of Pyrocat-HD that may have accumulated in the drum, so I gave everything a good cleaning. When I tested a few more sheets (in the same drum), I got the same results. This is the first time I have used the TD16 developer, but I have used actual D76 in the past with no problems. Any idea what could be causing the problems here?

I have still have a couple of batches of Tri-X to process - has anyone had good success with the Pyrocat / Tri-X combination in Expert Drums? If so, at what development specs?

ronald moravec
1-Nov-2005, 15:26
I think there are reactions from standard developer and pyro. I did a 6 sheets in a previously good batch a PMK in a tank previously used for d76, but visually clean. Six sheets came out almost totally blank. Tf4 used in both cases.

I would not mix developers in a tank used for pyro developers.

Jay DeFehr
1-Nov-2005, 16:24
Hi Jeff.

I'm sure the pyrocat in your case, or the PMK in Ronald's, didn't have anything to do with your respective results. Pyrogallol, and especially catechol, are not very different, chemically, from hydroquinone. I would look elsewhere for the root of your problems.


Michael Gudzinowicz
1-Nov-2005, 18:22

Enlarge or look at a section of the film under high magnification (50 mm lens) and see if it is

I don't know what the composition of Bill's TD16 might be, but I suspect that it is quite
basic. If so, the cross-links hardening Tri-X are weakened and that can be compounded by
aged film. When developing very old film (> 40 yrs.), I harden them before development
or the emulsion may wash off. That is unlikely in your case.

If you use a water stop with an "older" film (TMAX is hardened for 100F processing),
the salts and charged ionic sites in the gelation act as if their concentration is very high
and they are unable to diffuse rapidly if at all (gelatin). Water will try to dilute those ionic
sites which results in emulsion swelling due to osmotic pressure. The film can swell to 10X
it's normal hardened thickness, and since lateral expansion is limited, it tears from the base
and folds (ripples). That is the mechanism of reticulation. It occurs to a greater degree in
warm solutions that soften gelatin. It has absolutely nothing to do with small temperature
differences or other unfounded speculation. The effect has been known for over 100 years.

The problem may be compounded by a basic fixer which does not permit hardening to
occur in a limited pH range (around pH 4 to 5.5). The fixer provides another basic solution
of high osmotic content, and a water wash can blow it apart if the film is old or has had
the hardeners compromised. Tanning developers may harden the film and prevent or
mitigate the effect.

Kodak's and other manufacturer's old recommendations that films be stopped with an
acid stop of moderate concentration (osmolarity), followed by an acid fixer with or
without hardener, and then treatment with a wash aid are very well grounded. Unanticipated
problems may occur with certain emulsions and treatments. Even those recommendations
are inadequate to stop reticulation of "older" (non-TMAX) films so tropical developers and stop baths
were introduced.

The details are in most of the "research grade" photographic chemistry texts.

I use the "old fashioned" acid stops, hardening fixers and a wash aid with Tri-X without any
problems. I can generate the problem you have with the swollen slippery film which may
never dry completely (or sufficiently so that it is "hard").

If you can salvage any negatives for small prints, consider treating them a hardener mixed
from scratch or Sprint's Hardening Converter added to an acid stop bath.

BTW, the alkaline fixer shortcut will work most of the time, but not all of the time.

Take care,


John Berry ( Roadkill )
1-Nov-2005, 19:26
Thanks, Michael. I have never had this problem, but this is why I live on this forum. There is always someone here that has some info on any problem. This is where I gits me edgymucation.

Jeff Dyck
1-Nov-2005, 22:16
Thanks for the very informative post Michael.

I took a look at the film under magnification, and you are correct - what I was seeing was not grain but reticulation. The effect seems more pronounced (or more visible anyway) on the denser portions of the negative - on some of the images it is actually quite an interesting effect! I checked on the film this morning and it was still wet in the middle (it appeared that only about an inch around the periphery had completely dried. Now, a little more than 24 hrs later the film seems to be mostly dried all the way through.

I will switch to an acid stop and hardening fixer for the remainder of the batch and hope for the best...

Thanks again,

Eric Rose
2-Nov-2005, 10:07
I flip back and forth between HC110 and PyroCat-HD all the time and have never had this problem. I use a water stop and Ilford fix.