Agitation in PMK : LUSENET : B&W Photo - Film & Processing : One Thread

Hi. I know that most people use agitatation in 15 sec intervals when processing roll films in PMK. Is there any special reason for that? PMK is quite slow working, so I would think uneven development is not the main reason and agitation will kill any compensating effect. Also, frequent agitation may cause some loss of speed. Anyhow, I would like to hear if somebody have tried different agitation rhytms in PMK and what the results looked like. I would appreciate any comments and tips on using PMK. You can also use my e-mail address

-- Evgeni Poptoshev (, February 24, 1999


Try this site dedicated to pyromaniacs:

-- Harold Todman (, February 24, 1999.

Correct agitation is fairly critical when using PMK or any other pyro developer. The main reason is not necessarily uneven development but pyro has a strong tendency to cause streaking which will ruin your neg. During development a very thin layer of the developer will exhaust itself rapidly on the surface of the film. When there is no agitation (the agitation should be very vigorous) this layer of exhausted developer will begin to slide across the surface of the film causing the stains(streaks). Gordon Hutchings describes in detail the why's and how's of PMK and agitation in "The Book of Pyro." I have used an agitaion cycle of 10 sec. every 30 sec. which is longer than recommended with apparent success. Temperature and capacity are also really critical with pyro. Before I knew PMK was a one-shot developer, I ran three 4x5 negs. one at a time through the tray of PMK. When I was finished and turned on the lights I found the first neg. was beautiful but the other two were blank. 1 liter of PMK was fully oxidixed after just one neg.! (It has a larger capacity than this but the exposure to air oxidized it quite rapidly)Finicky stuff but can produce wonderful results.

-- Brian Jefferis (, February 25, 1999.

I too use 10 seconds of agitation every 30 seconds and have had no problems with uneven development.

-- Ed Buffaloe (, June 04, 1999.

Evgeni, I am comitted to both PMK and Paterson tanks. I do my development of Iford 400 Delta shot @ EI 200 @ 75 degrees F. I use 1 Inversion per minute--The paterson tanks give very vigorous agitation if used properly. This goes against Hutchings info, but it works for me. Kevin

-- Kevin Kalsbeek (, June 20, 1999.

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