Divided PMK developer

Corn_Zhou · Oct 7, 2023

Upon reading the divided pyrocat by Sandy King.

Two Bath Pyrocat HD Film Developer

In the article published in View Camera I reviewed the use of D23 and Diafine in two-bath use. Shortly after the article came out I began experimenting with

www.pyrocathd.5x4.co.uk

I have been interested in a pyro divided developer. I tried the formulation given by Sandy King which is Pyrocat A 1+15 followed by B 1+15 and found it gives beautiful images but thin negatives.
So I tried a similar approach with PMK pyro with some minor adjustments. The formula is given below:
Bath A:
PMK part A ----------------- 100mL
Sodium Bicarbonate ------- 20g
Cold water to -------------- 1L
Bath B:
Sodium Carbonate -------- 30g
Cold water to -------------- 1L

5min in Bath A followed by 5min in Bath B with 10s agitation per minute produces a nice negative on Kentmere400 with a good amout of stain.
It is not particularly fine-grained but gives good sharpness, film speed and compensation.
Scans and the negative is posted below.

Kentmere 400-Lomo LCA 120-PMK 2bath-7 by Kelvin Zhou, 於 Flickr

Kentmere 400-Lomo LCA 120-PMK 2bath-1 by Kelvin Zhou, 於 Flickr

Kentmere 400-Lomo LCA 120-PMK 2bath-8 by Kelvin Zhou, 於 Flickr

koraks · Oct 7, 2023

Welcome to Photrio @Corn_Zhou and thanks for posting your experiences with divided PMK! You mention you started with divided pyrocat; did you try enhancing the recipe of that one to give denser negatives?

You sure got a lot of stain with this approach; it actually looks very pretty on the negative!

Corn_Zhou · Oct 7, 2023

koraks said:
Welcome to Photrio @Corn_Zhou and thanks for posting your experiences with divided PMK! You mention you started with divided pyrocat; did you try enhancing the recipe of that one to give denser negatives?

You sure got a lot of stain with this approach; it actually looks very pretty on the negative!

I haven't tried to adjust the 2 bath Pyrocat yet but I think 1+9 with a mild alkali added (10-20g/L Sodium Bicarbonate) would be a good starting point.
It's also notable that on Kentmere film that I tried (both 100 and 400) 2 bath Pyrocat produces a siginificant tanning effect, the relief image is very visible.

koraks · Oct 7, 2023

Thanks for following up; I recognize the tanning effect, indeed, with e.g. pyrocat. But I've only tried divided pyrocat once or twice and that was years ago. I tried it for taming the contrast on x-ray film.

chuckroast · Oct 7, 2023

Corn_Zhou said:
Upon reading the divided pyrocat by Sandy King.

Two Bath Pyrocat HD Film Developer

In the article published in View Camera I reviewed the use of D23 and Diafine in two-bath use. Shortly after the article came out I began experimenting with

www.pyrocathd.5x4.co.uk

I have been interested in a pyro divided developer. I tried the formulation given by Sandy King which is Pyrocat A 1+15 followed by B 1+15 and found it gives beautiful images but thin negatives.
So I tried a similar approach with PMK pyro with some minor adjustments. The formula is given below:
Bath A:
PMK part A ----------------- 100mL
Sodium Bicarbonate ------- 20g
Cold water to -------------- 1L
Bath B:
Sodium Carbonate -------- 30g
Cold water to -------------- 1L

5min in Bath A followed by 5min in Bath B with 10s agitation per minute produces a nice negative on Kentmere400 with a good amout of stain.
It is not particularly fine-grained but gives good sharpness, film speed and compensation.
Scans and the negative is posted belowKentmere 400-Lomo LCA 120-PMK 2bath-7 by Kelvin Zhou, 於 FlicKentmere 400-Lomo LCA 120-PMK 2bath-1 by Kelvin Zhou, 於 Flickr
Kentmere 400-Lomo LCA 120-PMK 2bath-8 by Kelvin Zhou, 於 Flickr

I have used PMK extensively in it's normal formulation and Pyrocat-HD for extended, very low agitation protocols. Several questions, if I may:

What EI did you use for the film?

What do you think the benefit of divided PMK is?

I ordinarily agitate PMK every 15 seconds in an open tank because of the high rate of aerial oxidation. Did you see any tendency toward uneven development with only 10sec/min?

Thanks!

Corn_Zhou · Oct 7, 2023

chuckroast said:
I have used PMK extensively in it's normal formulation and Pyrocat-HD for extended, very low agitation protocols. Several questions, if I may:

What EI did you use for the film?

What do you think the benefit of divided PMK is?

I ordinarily agitate PMK every 15 seconds in an open tank because of the high rate of aerial oxidation. Did you see any tendency toward uneven development with only 10sec/min?

Thanks!

1. The EI was 400 (Box Speed)
2. There is not very much development going on in Bath A and development in B is based on the developing agent absorbed in the emusion so normal agitation here would produce quite even results.
3. The benefits include: (1). Better film speed; (2). Extreme compensation; (3). Developing time and temperature are less of a concern.
As of the aerial oxidation, in a mildly alkaline solution like the Bath A I mentioned above, Pyro does not oxidize as fast as the normal PMK working solution. It is also possible to reuse the Bath A during one session as it oxidized less rapidly.

Doremus Scudder · Oct 7, 2023

The results you post are interesting, but this is not PMK; there's no "K."

K is for Kodalk, i.e., sodium metabisulfite, which is not in your formula. I'd suggest giving it another, more appropriate moniker. Especially since you can use the real PMK as a two-bath developer simply by soaking the negative in (the unmodified) part A and then following that with a bath in (the real) part B, which is a sodium ~~metabisulfite~~ metaborate solution, not carbonate. Since the use of divided PMK with the original components has been described here and elsewhere, that would avoid confusion

Best,

Doremus

Anon Ymous · Oct 7, 2023

Doremus Scudder said:
K is for Kodalk, i.e., sodium metabisulfite

I suspect you meant to write metaborate.

chuckroast · Oct 7, 2023

Doremus Scudder said:
The results you post are interesting, but this is not PMK; there's no "K."

K is for Kodalk, i.e., sodium metabisulfite, which is not in your formula. I'd suggest giving it another, more appropriate moniker. Especially since you can use the real PMK as a two-bath developer simply by soaking the negative in (the unmodified) part A and then following that with a bath in (the real) part B, which is a sodium metabisulfite solution, not carbonate. Since the use of divided PMK with the original components has been described here and elsewhere, that would avoid confusion

Best,

Doremus

PMC?

chuckroast · Oct 7, 2023

Corn_Zhou said:
1. The EI was 400 (Box Speed)
2. There is not very much development going on in Bath A and development in B is based on the developing agent absorbed in the emusion so normal agitation here would produce quite even results.
3. The benefits include: (1). Better film speed; (2). Extreme compensation; (3). Developing time and temperature are less of a concern.
As of the aerial oxidation, in a mildly alkaline solution like the Bath A I mentioned above, Pyro does not oxidize as fast as the normal PMK working solution. It is also possible to reuse the Bath A during one session as it oxidized less rapidly.

I wonder if sodium hydroxide could be added to your first half in lieu of sodium bicarbonate, though I suspect very little would be needed.

I've used D-23 mixed 1+9 and added 0.5g/l of sodium hydroxide (lye) to bump up the alkalinity for long, low agitation development to give me much the same thing: Improved sharpness, full box speed, and strong highlight compensation. Even at 1:4, D-23 has too much solvent effect for my tastes, so that concoction is my go-to if I am not using Pyrocat-HD.

I do find your approach temping, however. because I love the edge transitions on clouds that the Pyrogallol in PMK gives me (noting that you are not actually making PMK).

john_s · Oct 7, 2023

chuckroast said:
PMC?

There was a developer called PMC. It was Sandy King's precursor to Pyrocat-HD. I used it for a couple of years. You can find it probably at

rec.photo.darkroom | Google Groups

john_s · Oct 7, 2023

PMC formula for academic interest. I copied the text in 2004 but I don't have date for Sandy King's original post.

<start quote>

Yes, the PMC formula, which seems very stable in working solution, keeps
well in A and B concentrated solutions. And yes, the same procedures and
conditions (low sulfite and alkaline processing) that are used to intensify
staining with PMK also apply to Pyrocatechin. But no, I don't intend to
write "the book of catechol." Too many other writing projects on hand for
that.

The stock solutions are prepared as follows.

Stock A
Distilled Water 75ml
Sodium bisulfite 1g
Pyrocatechin 5g
Metol .25g
Water to 100ml

Stock B
Distilled Water 750ml
Sodium Carbonate 100g
Water to 1000ml

Dilute 1 part A + 10 parts B + 100 parts water to make a working solution.
For most films development times should be about 15-20% less than with PMK
to reach the same CI. The working solution has a pH of about 10.4, in
contrast to about 9.6 for PMK.

Sandy King

Corn_Zhou · Oct 7, 2023

chuckroast said:
I wonder if sodium hydroxide could be added to your first half in lieu of sodium bicarbonate, though I suspect very little would be needed.

I've used D-23 mixed 1+9 and added 0.5g/l of sodium hydroxide (lye) to bump up the alkalinity for long, low agitation development to give me much the same thing: Improved sharpness, full box speed, and strong highlight compensation. Even at 1:4, D-23 has too much solvent effect for my tastes, so that concoction is my go-to if I am not using Pyrocat-HD.

I do find your approach temping, however. because I love the edge transitions on clouds that the Pyrogallol in PMK gives me (noting that you are not actually making PMK).

The purpose of having bicarbonate in Bath A is to make it a slow developer.
PMK part A is acidic due to the Bisulfite so the idea is to add a weak alkali to it so the developing agents could start to work just like divided D23 or Emofin. This should boost the density obtainable.
The dilute D23 you mentioned is akin to Beutler or Kodak HDD with high pH and dilute agents, this would give good compensation effect but works differently from the divided "PM-Something" developer here.

Doremus Scudder · Oct 7, 2023

Anon Ymous said:
I suspect you meant to write metaborate.

Indeed... typing too fast and not engaging the brain fully. Thanks for the correction.

D

john_s · Oct 7, 2023

chuckroast said:
I wonder if sodium hydroxide could be added to your first half in lieu of sodium bicarbonate, though I suspect very little would be needed.

...........................................

It wouldn't take much hydroxide to turn the Part_A into a full-blown developer rather than the first part of a truly divided developer, which I gather is the point of the OP's experiment.

Divided PMK developer

Corn_Zhou

Two Bath Pyrocat HD Film Developer

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