Response to Agitation in PMK

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.

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