Rotary processing with any pyrogallol based developer. with or without presoaking, is risky. I say this in spite of the fact that quite a number of people make beautiful negatives with developers like PMK and Rollo Pyro in Jobo, tubes, and drums. In spite of their success the reports of failures due to irregular staining, rib marks, marks on the back of the film, etc. are numerous.

I used PMK for many years as my main developer of large format sheet film, with tray processing. However, when I started to use PMK with rotary processing, in BTZS tubes and print drums, I experienced many of the problems mentioned above. These failures were one of the primary reasons I developed the Pyrocat-HD formula, based on pyrocatechin (or pyrocatechol). In my opinion there is no question but that pyrocatechin is a much better reducer (cleaner working and less tendency to irregular and uneven staining) for use in rotary type development than pyrogallol, and I am sure that many who have compared Pyrocat-HD in this application to staining developers based on pyrogallol would agree.

Some information on Pyrocat-HD is at ://

Sandy King