PMK Pyro - Agitation Question

I recently made up some PMK Pyro developer from some dry ingredients I have had for a while. The fact that I am writing this proves that I am still alive and didn't poison myself in the process.

Anyway, I have processed a film with it and like the results but have a question about agitation. Most of the instructions I found, both official and on-line recommendations, suggest agitation every thirty or even fifteen seconds.

Whilst I don't have a problem doing that, I wondered why Prescysol, the only other staining developer I have used, is recommended to be used partial stand. i.e. 10.5 minutes with (I think) only three agitation stages.

Is Prescysol not a Pyro developer too? Any reason for the difference?


Steve.

Steve, I use 4 inversions/minute( my standard for everything)with outstanding results. I once read(can't remember where) that agitation frequency/timing is a cumulative effect, and somewhat inconsequential. The caveat is the chance for streaking, bromide drag, in sky areas from lack of agitation.

Rick A said:

The caveat is the chance for streaking, bromide drag, in sky areas from lack of agitation.

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That's what I have read too and I have no reason to not believe it. I was womdering why Prescysol did not suffer from it. Perhaps it is significantly more different to other pyro developers than I thought.

I know we are not supposed to talk about such things here but so far I have only scanned these negatives, not printed them, but I think many of them will require no or very minimal dodging and burning to make them look good.


Steve.

Prescysol is a pyrocatechin type developer, and PMK is pyrogallol based. They are two different compounds and while both are staining (tanning) developers, grain structure, stain color, etc is different.

I've used PMK, but didn't really deviate from the recommended agitation intervals, so can't tell what would happen if you went longer from experience. But reports from around the internet of uneven development scared me into just agitating every 15 seconds as prescribed.

It worked really well for me, but I didn't want to deviate from my normal process to much, so went back to Xtol.

Hope you're having a good time with PMK. If you can lay your hands on some graded paper, you'll find some interesting contrast rendition compared to variable contrast paper.

Thomas Bertilsson said:

Prescysol is a pyrocatechin type developer, and PMK is pyrogallol based.

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Thanks. I have just realised that and returned here to point out my stupidity but you have done it for me!!


Steve.

I used PMK for some time, always following the package directions. If I had roll film exposed in higher-contrast situations, I would let the film stand for a minute at a time during the last couple of minutes of development. I experienced no problems with drag or uneven areas. I've since moved away from PMK to Pyrocat-HD, which I find much more versatile. I abandoned PMK for 35mm Tri-X early on because it gave me too much grain. 100 ISO films and T-grain films in 35mm were not a problem.

I have used PMK standard dilution for dozens of films and I did agitation fairly vigorously for 2 minutes then once every 2 or 3 minutes thereafter. I had no unevenness except when I didn't do a pre-rinse. I don't know why, but I do know what has worked.

For Large Format and PMK Pyro I use a rotating drum, so it's constant agitation. For smaller formats, I follow normal patterns. Constant for the first minute, then for 10 seconds every following minute. The agitation is very gentle using the inversion technique.