Who’s using PMK for rotary / jobo processing?

[Tim V]

Hi all,

Now that I’ve been using Pyrocat-HD in the Jobo for a while (75 sheets of HP5) I have a suspicion I preferred the end results, particularly the handling of highlights (compression with VC paper,) with PMK, which I used extensively for 8x10” sheets processing in trays with constant agitation. I like Pyrocat, it’s ultra sharp, just gives a slightly different look that I’m not quite as into. I think... the addition of the Jobo perhaps muddies the water somewhat. Perfect, streak free negs though!

I’ve read of people using PMK in the Jobo and changing the developer halfway through the dev stage to help minimise oxidisation, but also of others adding another solution in the pre-soak and / or with the developer to help with same. What do people do, and with what reliability?

I like buying my developer from Photographers Formulary and next order thought I might get some more PMK (premixed) to do some testing but wonder what else I need to buy to add to the soup to aid in the above, if anything at all. I see Bergger offer a PMK Rolo additive, but i have no idea what it is or does, let alone how it effects processing times etc.

Lastly, I’m happy enough with Pyrocat and went with it when changing to Jobo because I wanted stain and was scared of wasting film using PMK trying to avoid its known pitfalls with rotary, while also trying to master the mechanics of the Jobo processor itself. Now I know what both can do, at least I feel comfortable using both, I feel it’s a good time to experiment...

Thanks,

T

[Pere Casals]

For rotary, the direct PMK substitute is Rollo Pyro, less prone to oxydation, thus avoiding general stain increase of PMK in the rotary processing. Basicly Rollo is PMK with (ascorbic) anti-oxydizer... isn't it ?


Rollo has worse keeping properties than PMK because the ascorbic acid added to prevent oxydation will degradate with time. I guess you may make the Rollo concentrate with no Ascorbic, and then adding the Ascorbic acid to the working dilution just before using it, so you would have best of both choices: anti-onxydation of Rollo and long shelf life of PMK.

You may also try 510-Pyro...

[PRJ]

I use JOBO tanks, a 3010 and 1500, with a modified Beseler rotary base and PMK and I don't have any issues. I use a lot of developer though. I think that is the key. I use a liter in the 3010. You'd have to check to see if the JOBO motor could handle that much. I think that may be part of the reason why people split development. when I develop medium format in the 1500 I basically fill it up. The PMK comes out barely changed. I've never added anything else to it. if you start adding Sulfite to minimize oxidation, you will kill the stain.

Like you, I think PMK has better highlights than Pyrocat. After using PMK for a decade, then Pyrocat for 15 or so years, I went back to PMK after looking at all the prints I've made. A lot of people buy the "theory" of the different color stain, but I look at the prints. I also had issues with Pyrocat over the last few years with streaking. Never had an issue with PMK. Part of the hullabaloo for Pyrocat was the dual purpose neg. One that could be printed both on silver and alternative methods. That was the original reason for me to switch. These days pretty much everyone does digital negs for alternative processes, so the dual purpose stain is pretty much moot.

Hope that helps you.

[bob carnie]

I use Jobo and PMK - I do change the developer half way between the development and I do use the exhausted first developer for final bath stain.
I too feel PMK is awesome and over the last 25 years have had very few complaints about the quality of my silver gelatin prints from PMK. I find it humorous to hear that the stain is bad, generally this comment comes from non silver printing users and for the life of me do not want to get into arguments on the internet with these blasphemers.

PMK mixed in Distilled water.... 20 ml A 40 ml B -- divided into two 1 liter bottles.

Water Bath 1-2 min- 1 liter
7 min Dev bottle 1- capture this and put at end of line - 1liter
7 min Dev bottle 2 - 1 liter
40 second Water stop- 1 liter
5min Fix - 1 liter
Stain 2 minutes- 900ml

wash film

I have processed PMK like this since 1994 with two Alt 2300's and now the CPP3 which I use in all manual rotation. During this period of time I chose ID11 and Microphen as the other two developers that I would offer
my clients with PMK.



for tricky skys and nuetral backgrounds I will take the drum off the machine after the pre soak water bath Pour in the first Developer and INvert and Twist for the first 15 seconds of development, I have found that
this solves any flo mark or rotation issues with a Jobo Processor.

[Bernice Loui]

PMK with Jobo 3000 series or expert tanks should be run at the lowest speed of the jobo processor to prevent excessive base fog. Excessive oxidation can be reduced by filing up the drum with a lot more developer than recommended. This can stress out the jobo processor.

Another way to prevent excessive oxidation with PMK is to nitrogen purge the tank before running in the processor.

Problem of base fog and excessive oxidation with PMK is covered the Gordon Hutching's "The Book of Pyro".


The attraction of Pyro staining developers has much to do with making prints on silver gelatin paper. The stain can act as a contrast reduction aid for variable contrast papers that can help with highlight burn out. Overall, PMK negatives printed in Silver Gelatin papers do have a different look than non-staining developers, PMK and other staining developers are not a panacea for all image making needs it is just one other image making process tool that has something to offer as a solution to the creation of image making.


Bernice

[Doremus Scudder]

Adding ascorbic acid to PMK for more activity (PMKC)


Sandy King described a technique of adding ascorbic acid to his Pyrocat developers to both prevent oxidation and increase activity. I surmised that the same thing would apply to PMK (as with the Rollo-Pyro formula) and have experimented with it as follows:

A very small amount of ascorbic acid, 0.05-0.1 g/l of working solution is added to PMK. The super-additivity effect seems to increase the activity of the developer while minimizing film base + fog densities. King thinks the optimum amount of ascorbic acid to add a liter of working solution is 0.1g.

For ease of use, I mixed a 0.5% ascorbic acid solution, i.e., 0.5g in 100ml of water (or equivalent), and use this as the PMKC “Stock C” solution.

My preliminary tests were with PMK diluted 2:4:100 (double strength) with ascorbic acid added to make 0.1g/l (I added 5ml of a 5% solution to 500+ml total solution).

The PMKC formula I used results in more and greener stain than PMK in normal dilution. This could give more contrast and more grain masking. Certainly, the developer is more active, and could be of use with greater expansions. I have some N+ negatives I've developed this way and they print nicely, but I've not done a direct comparison to PMK without the ascorbic acid added.

Rollo Pyro is actually stronger that the double-strength PMK I used, but the compromise seemed to work quite well. With a bit of tweaking and experimentation, It would likely work well for rotary processing.

Here are the formulas for PMK and Rollo Pyro for comparison:

PMK Pyro Formula
Stock Solution A
Distilled Water (125 degrees F) . . . . . . . 400 ml
Metol . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 g
Sodium Bisulfite* . . . . . . . . . . . . . . . . . . . 10 g
Pyrogallol . . . . . . . . . . . . . . . . . . . . . . . . . 50 g
EDTA (optional) . . . . . . . . . . . . . . . . . . . 2.5 g
Cold water to make . . . . . . . . . . . . . . . . 500 ml

Stock Solution B
Distilled water . . . . . . . . . . . . . . . . . . . . 700 ml
Sodium Metaborate . . . . . . . . . . . . . . . . 300 g
Water to make . . . . . . . . . . . . . . . . . . . 1000 ml

Make a working solution by mixing 1 part A with 2 parts B with 100 parts water. To make 1 liter of working solution add 10 ml of A and 20 ml of B to 1000 ml of distilled water.

Rollo Pyro
Stock Solution A
Distilled water . . . . . . . . . . . . . . . . . . . . 400 ml
Metol . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 g
Sodium Bisulfite*. . . . . . . . . . . . . . . . . . . 10 g
Pyrogallol . . . . . . . . . . . . . . . . . . . . . . . . . 75 g
Ascorbic acid (Vitamin C) . . . . . . . . . . . . 5 g
EDTA - Na4 . . . . . . . . . . . . . . . . . . . . . . 2.5 g
Water to make . . . . . . . . . . . . . . . . . . . . 500 ml

Stock Solution B
Distilled water . . . . . . . . . . . . . . . . . . . . 950 ml
Sodium Metaborate . . . . . . . . . . . . . . . . 150 g

Make a working solution by mixing 2 parts A with 8 parts B with 100 parts water. This pyro solution is designed as a substitute for PMK and provides even development with tube processors running at 25 rpm. Developing times range from 5 to 7 minutes.

*Thanks to Unblinking Eye for the formulas; https://unblinkingeye.com/Articles/D.../formulas.html

Best,

Doremus

[Jim Noel]

I keep Rollo Pyro on hand for those rare times when I decide to use the Jobo,or am working with 4x5, or 5x7. My larger films I prefer to use trays and develop by inspection with Pyrocat.

[Daniel Unkefer]

Twenty five years ago I was using an 8x10 Unicolor print drum on a Uniroller with Pyro PMK+
Now I am about to start printing those negs.

Now I use Multitank 6 and 5 still with same Uniroller

[Chauncey Walden]

I just use Gordon's recommendation of the equivalent of 5 ml/l of a 10% EDTA solution added to the minimum amount of the developer required (300 ml per 8x10 equivalent) when mixed. Never had problems.

[Andrew O'Neill]

I used to use Rollo back in the 90's with BTZS tubes. Worked well, but I preferred the brownish Pyrocat-HD stain over Rollo's greenish stain. Personal choice.