PMK Pyro, Alternative Dilutions?

[DREW WILEY]

I dunno. Chlorofluorocarbons in hair spray once killed a lot of women, and people using spray contact cement too, especially in the picture frame trade for a decade or so. That was a long time ago. But there are still ingredients in things like nail polish illegal to use in industrial products due to known serious health issues. I use PMK in the darkroom, but always wearing nitrile gloves. I sure wouldn't want it on my skin.

 

[chuckroast]

I dunno. Chlorofluorocarbons in hair spray once killed a lot of women, and people using spray contact cement too, especially in the picture frame trade for a decade or so. That was a long time ago. But there are still ingredients in things like nail polish illegal to use in industrial products due to known serious health issues. I use PMK in the darkroom, but always wearing nitrile gloves. I sure wouldn't want it on my skin.

Yeah, I use nitrile when handling PMK or when making or using Pyrocat-HD. When I am making the latter, I also wear an N95 mask and eye protection, have a lab apron on, and run the fan continuously.

An ounce of prevention is worth a pound of cure, and as they say, the dose makes the poison.

 

[Doremus Scudder]

I wonder if increasing the alkalinity of Part B or just adding more of it would effectively make the development more aggressive. Have you ever measured the default pH of "proper" PMK?

I do know for sure that decreasing the amount of Part B with PMK reduces developer activity. I had a batch of Part B that precipitated out a lot of the metaborate, which I didn't notice till too late. Result: thin negatives. Increasing the amount of Part B seems to do the opposite, but I've never measured (nor have I measured pH).

Doremus

 

[Doremus Scudder]

I have no access to a rotary processor. I only have open rubber tanks and daylight Nikkor tanks all of which require me to be the agitator ... something I've oft been called....

You don't need a rotary processor or even tubes to use Rollo Pyro. It works fine in trays and tanks as well. It was formulated to reduce the oxidation so the developer didn't exhaust from that before development time was up when sloshed around by the rotary processor (Bob Carnie solves the problem by dividing developing time in half and adding fresh developer halfway through). That works fine in trays and tanks too. My thought was that the addition of ascorbic acid might have a superadditive effect. I do seem to get more contrast by adding ascorbic acid to PMK, but, as I mentioned above, I really need to test it more to have definitive data.

 

[kzhou22]

Embarrassing to say, long ago I got a pack of PMK powder from Photographers' Formulary that makes 25L but I ended up making 50L out of it! I developed at least 30 sheets of hp5 8x10 sheets with the recommended times at iso250-320 in a 3005 tank both using the two-bath rotary method and "once per 15 seconds" hand inversions for the first two weeks (13.5~15.5min, depending on scene and exposure, water stop, fixed with TF-4).
It was my first time with any pyro, so I had no idea how PMK negs are supposed to look like, and thought the rather thin negs and heavy yellow general stain out of this 1:2:200 dilution was normal (I tried to persuade myself it's "yellowish-green" stain but I just can't).
But the prints turned out more than fine; the shadows are well-compensated, the highlights are much easier to print than before, and the moody day shots look stunning. When I realized my mistake and switched back to normal dilution with slightly less dev times at iso 320, the contrast was a lot higher and the stain was finally green. The printing was still easy and the results were still great, but not as brainless as previously. I'm going to do some controlled 4x5 tests with a densitometer and 21 step wedge next week to see the real influence.
The attached picture is a random phone photo of the print right out of fixer from a 1:2:200 hp5 neg, iso 250.

 

[Rick A]

I just wonder what their hair smelled like wearing the same helmets afterwards, or even if they still had hair? But they had worse things to worry about. Pyrogallol residue would have given the scalp a nice tan.

Unlike modern kevlar helmets, WWII helmets were steel pots with a separate liner originally made of paper fiber (which decomposed rapidly ) then plastic (thank you GM for the innovation). GI's used the steel pots for many thing, not the least was for cooking or heating water to wash up in (or even a chamber pot at times).