PGK pyro

I have often used apug for research but have never posted before so firstly - hello.

I have been experimenting over the weekend with some interesting stuff and thought that I would post my results here for discussion. Its early days and I have done very little testing as yet so there are merely first impressions and assumptions based on what little evidence I have observed so far.

I decided to replace the metol in PMK with 2.5x its weight in glycin. From the results of searches on both APUG and the web, it seems that nobody has tried (or at least documented) this. Because gycin has solubility issues I added it in the B solution rather than the A. The formula is as follows:

Solution A:

Distilled Water - 75ml
Sodium Bisulfite - 2g
Pyrogallol - 10g
Distilled water to make - 100ml

Solution B:

Distilled Water - 120ml
Sodium Metaborate - 60g
Glycin - 2.5g
Distilled water to make - 200ml

Dilute 1:2:100 @ 20 degrees C

The formula seems to have greater superadditivity and therefore activity than the combination of pyro and metol. It has similar image stain to PMK (possibly a little more green and less yellow) and very little general stain. It seems that it does not require the frequent agitation necessary to get even development with PMK. I successfully developed Plus X with constant agitation for the first minute followed by 4 inversions every 5 minutes for 17 minutes. The resulting negs were very even with no streaking. However they were quite thin and I would increase development time if I re-ran the experiment. Early tests suggest that stand development would probably be possible with this formula.

I can only comment on the tonality observed from my test subject (a mennequin strobe lit in the studio against black background with no speculars or areas of extreme highlight). As far as I can tell it shows excellent midtone separation but the highlighs are slightly less glowy than with PMK. In all, the look seems pretty similar to PMK with a little rodinalness (this should be a word) thrown in. Grain is excellent - tight and smooth, reduced agitation shows no increase in grain(!). This is all purely subjective right now and based entirely on eyeballing scanned negatives. I plan to conduct side by side tests of PGK against PMK tonight.

No idea about the film speed yet - I havent had time to test it. It doesnt seem to be any slower than PMK and might well be faster.

Your comments and suggestions are more than welcome. Please note however that I am not proposing that this formula might be superior to your chosen developer and therefore I'm not interested in defending its qualities against any other formula.

Hi Mike & welcome. I found your dev interesting in that you put the glycin in "B". I can't recall a formula like that! I'll have to give it a try!

the glycin is only in B because it wont dissolve in A!

mikemarcus said:

the glycin is only in B because it wont dissolve in A!

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Yes, glycin likes to dissolve in an alkaline solution! I've always seen glycin added late in the mix to make sure it's dissolved in alkaline solution;it's just that I've never seen it in "B" part. I'm looking forward to trying it.

I was looking for other solvents which glycin might be soluble in. The only one I could find was TEA which would need to (at lest partially) replace the metaborate therefore making the formula less PMK-like.

If anyone happens to know of a way in which I can dissolve the glycin in the A solution without affecting the formulas properties (antifreeze? cough mixture? rum and coke?) I'm all ears.

You could leave out the bisulfite, add a bit of acorbic acid, and mix the A in propylene glycol. I don't know if glycin is soluble in glycol. If so, you can throw it in too. If it keeps well as you have it, well and good.

Other possibilities: Pyro is soluble in glycol, which protects it from premature oxidation. The only need for the bisulfite then is to promote the superadditivity between pyro and glycin, which will be accomplished by a small amount of ascorbic acid. I have found that an amount of the metaborate solution can be replaced by an equal amount of triethanolamine (TEA for short) in the standard PMK working solution. It may be that glycin is soluble in TEA, and I know that ascorbic acid and pyro are. The number of combinations and permutations involving pyrogallol, glycin, propylene glycol, ascorbic acid and TEA are enough to keep you busy for a while, should you choose to undertake the mission.

Your reply came before I finished mine. So, we know that glycin is soluble in TEA, as is pyro and ascorbic acid. You might wind up with a single solution developer. When I suggested a small amount of ascorbic acid I meant something of the order of 2 grams per liter of stock solution.

My tests have resulted in both a messy kitchen and the knowledge that glycin is slightly soluble in TEA but not at all in Ethylene Glycol.

I'm not an expert in such matters but it seems to me that a developer which uses TEA as both solvent and activator would be fundamentally different from one which uses metaborate in the sense that metaborate is a buffered system and TEA is not. My research suggests that buffered solutions have a specific tonality due to the lack of change in PH during development. This is at least in part responsible for PMK's exceptional midtone separation.

I can confirm that glycin dissolves in TEA. I once tried a glycin/TEA only developer, but found it not energetic enough. Maybe the pyro alone would have made it workable - sort of a 510 Pyro with glycin added.
juan

I have dissolved 10g/L glycin in 10g/L sodium bisulfite solution by heating it in a stainless steel jug and stirring.With safety precautions I daresay your glycin could be dissolved. It's soluble in sodium sulfite,maybe the bisulfite too.See the entry for glycin here:
http://www.jackspcs.com/chemdesc.htm
However, in my developer, something (glycin?) precipitates out after a few weeks.

thats good to know Alan. I guess that dissolving the glycin in the A solution would increase its working life and make for a more flexible system. I will have to try it in my next batch.

I just read in the film developing cookbook that adding 50ml/l of isopropyle alchol stops glycin precipitation occuring in FX2 developer and possibly helps it dissolve (although other APUG threads have mentioned that glycin is insoluble in all alchols including Isopropyl). Maybe a workable formula would be:

Solution A:

Distilled Water - 75ml
Sodium Bisulfite - 2g
Isopropyl Alchol - 5ml
Glycin - 2.5g
Pyrogallol - 10g
Distilled water to make - 100ml

Solution B:

Distilled Water - 120ml
Sodium Metaborate - 60g
Distilled water to make - 200ml

This would involve dissolving 2.5 times the amount of glycin that you managed but maybe its possible (magnetic stirrer?).

For me the prospect of having a PMK type developer with no agitation issues is a big deal. Im off to create a mess in my kitchen now. I will report on any discoveries that I make.

The above is most interesting! However I am curious as to what problems you have with PMK to make you want to change it? I have been using PMK for some time and find that I develop HP5 for about 8 minutes with agitation every 15 seconds. Prints fine with a #2 filter on Multigrade fiber paper with a cold light. PMK seems to keep forever. I'm just not clear on what you chemical people are looking for. Times much less than 8 minutes seem to me a bit fast, since I'm standing in the dark anyway (sheet film in a 'slosher' the agitation gives me something to keep me awake.

I dont have any problem at all with PMK. However because PMK exists, does it mean that all further investigation into new formulae should stop for ever?

I believe my perfect formula would be exactly like PMK but suitable for stand developing with no grain increase over standard agitation techniques.

mikemarcus said:

My tests have resulted in both a messy kitchen and the knowledge that glycin is slightly soluble in TEA but not at all in Ethylene Glycol.

I'm not an expert in such matters but it seems to me that a developer which uses TEA as both solvent and activator would be fundamentally different from one which uses metaborate in the sense that metaborate is a buffered system and TEA is not. My research suggests that buffered solutions have a specific tonality due to the lack of change in PH during development. This is at least in part responsible for PMK's exceptional midtone separation.

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First, do you know as fact that TEA does not buffer? Second, if I used PMK A with metaborate and TEA as I said I had and did a controlled comparison, would you believe the results? If that is all that it would take to remove your lack of expertise in the matter, why not do the comparison yourself? If you have PMK on hand, you won't have to spend much time just to test your theory. One thing to remember is that diethanolamine is more basic in solution than triethanolamine. What is the end product when TEA does its alkaline work on one molecule of, say, hydrobromic acid?

juan said:

I can confirm that glycin dissolves in TEA. I once tried a glycin/TEA only developer, but found it not energetic enough. Maybe the pyro alone would have made it workable - sort of a 510 Pyro with glycin added.
juan

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Yes juan, I can also confirm that Glycin is soluble in TEA. The energy level can be easily be boosted by adding sodium or potassium carbonate to the working developer.

Patrick. I must confess to ignorance on this matter. When TEA enters solution with water does it self buffer?

As far as I am aware (and my knowledge on such matters is far from good) metaborate dissolves in water as Sodium tetraborate (borax) and Sodium hydroxide thereby forming a self buffered solution. Does a similar process happen with TEA?

I have a little bottle of TEA B solution mixed and waiting to be tested. Unfortunately I have much testing to do and very little time to do it.

Borax alone is a buffer. The pH of a borax solution does not change much over a wide range of borax content. The pH can be changed by adding strong bases like NaOH or strong acids like sulfuric. There are tables in the CRC Handbook for preparing solutions with wide range of pH.

As for TEA, you can search www.dow.com for ethanolamines and shold get a raft of informative charts and tables on MEA, DEA and TEA. The chart showing variation of pH with percentage of weight in water is of interest. A 40% solution of TEA gives pH=10.4 and a 0.04% solution gives pH=9.1. I also am not expert here, and I know pH is a logarithmic function, but it still seems to me that the pH of, say, PC-TEA after developing a roll (80 sq. in.) in 250 ml of working solution will not be very much different from what it was at the start. I have only test strips, and have not so far even tried using those for this test, but will soon.

When you say "mid-tone separation" that implies to me an s-shaped characteristic curve. (I know a funny story about that type of "s" that I could be persuaded to tell.) I'm not sure how that curve ties in with buffering. My impression when I tried TEA in place of the metaborate solution was that I couldn't tell them apart. We in my part of West Virginia do not often see vast stretches of cumulus clouds. About the farthest I can see at one time is 1/2 mile. Even when I go to the top of my hill, I can't see beyond the next hill top for the trees that cover the hills. They do qualify as mountains, being at least 1200 ft. high, but were once a great plain etched out by water into mountains and valleys. I diverse.

Anyway, when I did that test, I could not see a difference in gradation between TEA and metaborate. It is a possibility to keep in mind, although I am not sure a single-solution developer is best for other reasons. There are times when we excercise the ability to change the ratio between developer and activator. We do it often with PMK, the Pyrocat series, and other 2-part systems. This control might have more effect on midtone separation than buffering.

Patrick - I no doubt have a lot reading to do with regards to the activator. In time, its likely that the B solution will change to something else entirely. Thanks for the information. I have bookmarked it and will be delving into it when I'm ready to start tweaking the B solution.

On another note I made a couple of discoveries last night.

1) Although Glycin is barely soluble in either water or ethylene glycol it seems to be much more soluble in a mixture of the two. Last night I managed to dissolve 40g/l Glycin in 65% Water, 35% Glycol warmed to a moderate degree. This is good news because I can now return the glycin to the A solution where I feel it belongs.

2) In the Book of Pyro, Gordon Hutchings writes that increasing the ratio of metol to pyro increases speed but reduces stain. In PGK adding more glycin decreases speed. I suspect that decreasing the quantity of glycin would do the same. This suggests that if plot the ratio of glycin/pyro on a curve there will be a clear point where superadditivity is at its greatest. More work is required to find this ratio. When it is dicovered, I will change the formula to reflect the findings.

For now the formula has been modified to return the glycin to the A solution and is as follows:

Solution A:

Hot Distilled Water - 50ml
Sodium Metabisulfite - 2g
Ethylene Glycol - 25ml
Glycin - 2.5g
Pyrogallol - 10g
Distilled water to make - 100ml

Solution B:

Distilled Water - 120ml
Sodium Metaborate - 60g
Distilled water to make - 200ml

Im thinking of adding EDTA to the mix as well. I understand that the disodium salt is acid in solution while the tetrasodium is base. Is this correct? If so it seems that my two options are to add the disodium to A solution or the tetrasodium to the B. Does anyone have an opinion on the pros and cons of these two approaches? what g/l of working solution is a reasonable starting point?

Here are some rough results on a PGK Pyro type developer.
PGK 005 in order of mixing:
Part A
Distilled water 75 ml
Sodium sulfite 3g
Glycin 2.5g
Pyrogallol 10g
Distilled water to 100ml.
Part B
Distilled water 120 ml
Sodium metaborate 60g
Distilled water to 200ml
Take 1 part A , 2 parts B to make 100 parts working solution.
The glycin dissolves easily in the sodium sulfite solution on heating to 60 C and stirring. Sulfite not bisulfite was used to try to avoid any problem with solubility or precipitation of glycin,possibly at the expense of longevity.

I took some pictures of a blank wall lit by bounced flash with 35mm Agfa APX 100 film and developed as follows:
(1) Minimal agitation in Pyrocat-HD 20 min 70F Agitate 30s then 10s every 3 min.
(2)Minimal agitation in PGK 005 45 min 70F Agitate 1 min then 30s every 9 min.
My first result suggests PGK 005 holds up better than expected in providing even development,though it takes a long time.More tests with real scenes would be needed to reach a conclusion.

Meanwhile repeated my experiment with using TEA in place of the Hutchings metaborate solution, volume for volume. 1 part A, 2 parts TEA, 100 parts water, HP5+, 15 minutes, 68 F gave negatives that are comparable to PMK 1+2+100, but a little more contrast. I had another pyro concoction sitting on my shelf for a couple of years that was much like Pyrocat MC, but using 75% as much pyrogallol instead of the catechol and dissolved in TEA which also was the accelerator. I used it as a single solution developer at 1:50 and got very good results. As you may know, the Metol requires removal of the attached sulfuric acid molecule to make it soluble in TEA. Perhaps the glycin, as it seems, would replace the Metol, a little ascorbic acid would replace the sulfite to enable the synergism, and a great developer would be born. My shelves are full and I'm too old to clean them off, though not too old to make a mess, so I'm only suggesting something to try some day.

Alan, what became of the pictures?

Patrick, the blank wall turned out to be not uniformly lit and pictures of it in the two developers not having much meaning.Here's one done in PGK 005 tho:

Alan: If you use a bit of Ethlyne Glycol in the A solution then the glycin will disolve without needing to swap the metabisulfite for sulfite. This ensures longevity of the A solution.

Developing times are pretty long, approximately twice that of PMK. This suggests that a dilution of 1:1:50 would be more appropriate. I wonder if development would still be even at this concentration? how would it affect grain? I tested different glycin/pyo ratios using my usual mannequin test subject using 1:2:100, 17.5 min @ 20c, 10 sec inversions every minute. The negatives were not dense enough. I need to do further testing tonight so maybe I change the schedule to 1:1:50, 10 min @ 20c, 10 sec inversions every minute and compare grain, tonality, etc. If you were planning on doing more minimal agitation tests, maybe try at this new dilution and report your results?

As far as I can tell from the small image, the tones of the grass, path, trees and shadow under the fountain bowl seem to be very close to each other in your uploaded pic (but the highlights look exceptionally well behaved). Is this something that you would have expected equally from another developer (Pyrocat-HD for example) or is it a property of PGK?

Patrick: My plan was to work on tweaking the formula in the following order:

1) Find the optimum ratio between glycin and pyro.
2) Find the optimum level of sulfite/bisulfite
3) Find the optimum PH

I feel that if the resulting PH turns out to consistent with the use of a sovent amine such as TEA then having the formula as single solution concentrate will be a definite advantage. However I can live with a two solution system if need be.

With regard to using ascorbate as a preservative and synergism enhancer instead of sulfite/bisulfite I have two questions:

1) What are the advantages? Is it a solubility issue? Are sulfite and bisulfite not soluble in TEA?
2) Dosnt the fact that ascorbate is also a developing agent at higher PH values have a massive influence on the action of the formula? Wouldnt the three superadditive pairs of ascorbate/glycin, ascorbate/pyro and pyro/glycin all have an effect on the negative, thereby creating a very different developer?

Meanwhile I ran a daylight clip test to find if dmax was affected by differences in pyro/glycin ratio. My results show that dmax is pretty much the same while there is 3,4 or 5 grams of glycin in the above 200ml stock A formula. 2 grams or less creates a progressive drop in density, 6 grams or more creates a progressive rise. I'm not quite sure what this means. It suggests to me that synergism between the two agents occurs at 3-5 grams/200ml Stock A but as the more glycin is added it essentially becomes a glycin only developer. This however is pure speculation. If anybody has an a better interpretation of the results, I would love to hear.

By 10g/200ml stock A, my standard mannequin test negative shows contrast similar to document film. This suggests that as ratio increases, dmax continues to rise steadily while toe speed drops.

I tried once using ascorbic acid as a lith developer for line drawings. It did fairly well with lots of bromide, NaOH and sulfite, but not as well as hydroquinone alone. Hydroquinone is known as a regenerator of Metol and Phenidone, but not without sulfite. Ascorbate regenerates Metol or Phenidone without sulfite. There's only so far we can go with rules of thumb about what's going to happen when we mix two or more things.

The effect of mixing Metol and either sulfite or ascorbate is shown to be the same for the same mole percent in the literature. I think I posted the chart once. You could ask Sandy King about his experience with using ascorbate instead of sulfite in the Pyrocat series of developers. It is difficult to distinguish between Metol-sulfite and Metol-ascorbate. It's more fun not to let theories stop me from trying something.

Last night I found a bottle of Pyro-Metol-C in TEA that I made a couple of years ago and forgot about. It is much like Pyrocat MC with pyrogallol in place of catechol. I used about 75% as much pyrogallol in some sort of pseudoscientific attempt to equalize activity, since pyrogallol has the heavier molecule and an extra OH. It works quite well. Metol as it comes is not soluble in TEA, but can react with TEA and a little water to get rid of the sulfuric acid that is attached to make it soluble in water. You might be able to get the same result with pyrogallol-glycin-ascorbic acid dissolved in TEA. I don't have any glycin to try it with.

Pyro, catechol and hydroquinone each give different stain colors. At my age, I'm often not in agreement with those who see green in pyro-developed film. Best test would be printing or a UV densitometer.

Best test would be printing or a UV densitometer.

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I gave up the darkroom for the scanner 10 years ago and have never looked back. I guess you are going to hate me now