Advice On Uneven Development On Film Edges

[Bernice Loui]

Began using PMK "pyro" developers soon after the publication of Gordon Hutchings book on Pyro developers in the later 1990's. Initially used PMK with 4x5 nikkor tank. This often produced uneven pyro stains on the negative and very uneven stains specially along the center spiral support of the Nikkor reel. Gave up on using the 4x5 nikkor tank with pyro developers.

Ended up using the 5x7 Jobo expert drum back filled with nitrogen with modest rotation speeds. This combo resulted in the most even pyro staining on the negative. It is possible the ribbing in side these tanks cause uneven fluid flow across the negative or pyro developer stagnation in specific areas which results in uneven pyro staining on the negative. Pyro developers depend on essentially even distribution and developer action across the negative during the development process to achieve uniform staining over the entire negative area.


Bernice

[IanBarber]

I am going to do another test and this time change the initial agitation a bit. It that doesn't work then I might have to learn tray processing

[Bernice Loui]

Tray developing with Pyro developers can work good (been there, done this). Be extremely careful as pyro is more toxic than common developers. Wear gloves and make sure the work area is well ventilated.


Bernice

I am going to do another test and this time change the initial agitation a bit. It that doesn't work then I might have to learn tray processing

[JohnF]

As well as the uneven development, I find linear ‘deposits’ on the non-emulsion side of the negative that correspond to the vertical struts in the negative holder in the Stearman tank. I was using 510 Pyro 1:200 with continuous agitation for 1 minute, then 1 minute every 7 minutes, and ending development at 25 minutes. This with FP4+

[koraks]

make sure the work area is well ventilated.

While this is in general of course always good advice, there's as far as I know no reason why ventilation requirements would be any more strict for pyro developers than for other darkroom chemistry. Pyro compounds are not volatile, they reside in a watery solution and hence there's no particular risk of dangerous volatile compounds.
Acetic acid stop bath is in fact far more troublesome in this respect.

Gloves are certainly a good idea and nitrile is probably a better choice than latex. In fact in general I wouldn't recommend latex gloves if only because they basically suck in just about every way imaginable.

[Raghu Kuvempunagar]

While this is in general of course always good advice, there's as far as I know no reason why ventilation requirements would be any more strict for pyro developers than for other darkroom chemistry. Pyro compounds are not volatile, they reside in a watery solution and hence there's no particular risk of dangerous volatile compounds.

Old timers used to mix Pyro developers fresh every time from ingredients. Pyro dust can be harmful if inhaled.

[Alan9940]

As well as the uneven development, I find linear ‘deposits’ on the non-emulsion side of the negative that correspond to the vertical struts in the negative holder in the Stearman tank. I was using 510 Pyro 1:200 with continuous agitation for 1 minute, then 1 minute every 7 minutes, and ending development at 25 minutes. This with FP4+

I've used 3 different versions of the Stearman tank holders and found this to be an issue with certain developers and certain films: not all, though. The problem for me was the randomness of these artifacts which lead me to give up on the Stearman tank.

[Alan9940]

Old timers used to mix Pyro developers fresh every time from ingredients. Pyro dust can be harmful if inhaled.

No one should underestimate the dust of pyro chemicals...IMO, all create quite a bit of dust. This is why I wear full protective gear and mix the pyro outside on calm days.

[interneg]

All these problems could be solved by implementing process controls, using regular trays and not using badly designed (and over-hyped) developers from a succession of not-photochemists.

[Steve Sherman]

A longer initial agitation for sure, the added density that results can easily be compensated for later in dev. stage after uniformity has been established. Also, with the EMA process, I have found the inversion method to yield more edge unevenness than a simple rolling agitation with change of direction every 20-30 seconds. Good luck