PMK verses Pyrocat-HD

Discussion in 'B&W: Film, Paper, Chemistry' started by RobC, Nov 29, 2007.

  1. RobC

    RobC Member

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    can someone explain the difference in print obtained between these two developers.
    Assume Identical subject taken at the same time and boh printed on graded paper (NOT vc paper).

    Also assume that testing was done to fit the neg development to the paper.

    So what I'm really asking here, is do both developers give an even spread of contrast on graded paper or does one of them favour highlight separation or shadow separation or one shadow separation and the other highlight separation or what?

    Also is one less or more grainy although I don't think that will be a problem with either and which one gives sharper images.

    Infact will I see any difference between the two?

    Thanks
     
  2. jim appleyard

    jim appleyard Member

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    I've not done complete scientific tests, but here are my observations: (I go bywhat looks good) PMK does best with graded papers; HD works on graded AND VC because of the difference of the stain color.

    I would say they are even in all other regards.
     
  3. Eric Rose

    Eric Rose Subscriber

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    Please review the archives. There is extensive and often heated debate around these issues.

    My advise is try both of them. The chemicals are cheap and your particular way of working may influence which one ends up being better suited for you.
     
  4. RobC

    RobC Member

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    I've read most of the threads on this and they all discuss about VC printing or film speed or mottling or stain colour etc etc but I found none which answer my question, so if you can point me at one that does, I would appreciate it.
     
  5. lee

    lee Member

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    I used PMK for over 7 years before I tried Pyrocat HD. The color of the stain is one variable (PMK is a decidedly green to yellow tint and Pyrocat HD is more of a brown stain) I believe that PMK may be more grainy than Pyrocat HD for smaller formats. Some may take issue with that last statement but it is my opinion. Both are sharp developers. The stain in PMK is a general overall stain that for some processes may be hard to print thru and that was one of the considerations Sandy King worked on when he was working on the formulations of Pyrocat HD. The stain seems to be contained in the image and d min seems to be clear. The last thing is PMK seems more likely to exhaust in a continual agitation situation (like a jobo). Pyrocat HD is good with continual agitation. For my applications (graded and VC paper) I choose Pyrocat HD. Good Luck on which ever you choose.

    lee\c
     
  6. PhotoJim

    PhotoJim Member

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    PMK is not as good with continuous agitation, I agree.

    PMK keeps longer as a stock solution. I have had it keep seven years with no reduction in activity. Some speculate it will keep much longer than this. Pyrocat-HD has a relatively short life (about six months, perhaps twelve) once mixed. This is not an awful life compared to many stock solutions but it is not as impressive as PMK.

    I like both developers. I tend to use PMK far more because the longevity is important to me (I tend to develop batches of film many months apart). I do find that PMK negatives are often much easier to print on VC paper than negatives developed with traditional developers, so in my experience, PMK certainly is compatible with variable contrast papers.

    Experiment. :smile:
     
  7. gainer

    gainer Subscriber

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    I see two errors in previous posts. The stain in PMK is not an overall stain, though it may have an overall component if used as originally proposed in The Book of Pyro. Even when it has an overall component, it also has a component that is proportional to the silver density.

    Second, none of the Pyrocat series need be short lived. The A solution can be put up (as we say in canning vegetables) in propylene glycol by the substitution of a small amount of ascorbic acid for the sulfite. It then lasts as long as you want to keep it. You will probably want to use it, though, before you get senile.

    If the color is the decider, you can use pyrogallol in the same formulation as Pyrocat, but use 2/3 as much. It also is quite soluble in glycol.

    In some respects, the Pyrocat series is more versatile than PMK, but that is a matter of opinion, as is just about everything we photo nuts do.
     
  8. dslater

    dslater Member

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    Hi Pat,
    Are you referring to the after-bath here or is there something else in the instructions that leads to more general stain?

    Dan
     
  9. lee

    lee Member

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    Gordon Hutchins no longer recommends the after bath with PMK. According to Mr Hutchins the after bath only adds to the general stain and is not really needed.

    lee\c
     
  10. PhotoJim

    PhotoJim Member

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    It is true that PMK has more general stain than Pyrocat-HD (it depends on the film) but there assuredly is image-proportional stain. An article in a magazine (Darkroom Techniques?) a few years ago demonstrated this. You can bleach the silver image out of the negative and still print the image, using only the pyrogallol-produced stain.

    I too have abandoned the after-bath. I think the after-bath tends to increase general stain moreso than image stain. I also have noticed no difficulty in attaining good stain after abandoning it, although I use an all-alkaline process which surely helps.

    I stand corrected on Pyrocat-HD's longevity. I'll order some propylene glycol and make up a batch this way and see how it fares.
     
  11. gainer

    gainer Subscriber

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    Be sure you follow the specific recipe for the glycol mix, as sodium sulfite is not soluble in glycol. I think you can get it ready mixed or at least in a kit from PF. Pyrocat made with pyrogallol is an interesting experiment as well. Use 2/3 as much pyrogallol as you would of catechol. That's only because it has 3 OH groups instead of the 2 of catechol.

    I think the Pyrocats are better for use in stand or semi-stand as far as grain, etc. than PMK. Using pyrogallol in the recipe for Pyrocat PC or MC gives IMO the color of PMK with the other
    qualities of Pyrocat.

    I have not had the overall stain problem with PMK because I never did the stain intensification bit, except possibly once. BTW, I wrote that article for what is now Photo Techniques. You can order a reprint of it. Search for "More Pyrotechnics" on the Photo Techniques site.
     
  12. palewin

    palewin Member

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    I was hoping Sandy King would reply to this thread, as he is the developer of the Pyrocat family of developers. In his absence, here is a response he posted in a thread about staining developers and VC papers:

    "There are several potential reasons to use a staining developer.

    1. high acutance
    2. grain masking
    3. capability of building higher contrast for alternative processes
    4. highlight compensation

    The first three of this reasons are valid for all printing processes, graded and VC silver papers, and for alternative printing. Highlight compensation only applies to VC silver papers, and then only if you do not use a VC filter #3.5 or greater (or dial in the equivalent magenta filtration with a color head).

    Sandy King"

    The original poster specified that he was NOT interested in results relating to VC papers, so only points 1-3 apply. I suspect that PMK and Pyrocat will be very similar regarding the first three points. (I am a long-time PMK user, and haven't experimented with Pyrocat. My experience is that PMK is high-acutance, and the grain-masking is effective for medium format and larger; I find PMK too grainy for 35mm. Many posts indicate that Pyrocat shares these characteristics, although I don't know about its use on 35mm. Also, one of the reasons for developing Pyrocat was the known oxidation problems of PMK in rotary processing, which is not recommended. )
     
  13. gainer

    gainer Subscriber

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    Here are a couple more interesting facts. TEA can be used as PMK B in place of the Kodalk. It seems to be the one organic base Hutchings didn't try for his excellent book. The only ingredient of PMK that is not soluble in propylene glycol (if you excuse the used of a little TEA and water to separate the Metol base from its H2SO4) is the sulfite, and a little ascorbic acid will substitute for that. In that case, PMK A in glycol is not greatly diferent from Pyrocat MC A with pyrogallol instead of pyrocatechin.
     
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  15. gainer

    gainer Subscriber

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    P.S.
    I would not be surprised if you could substitute p-aminophenol base for the Metol in the glycol mix. It is readilly soluble. It is probably the easiest of the Pyrocat formulas to make. Glycol, catechol, p-aminophenol base, ascorbic acid and mix. Warming helps the mixing, as the organic solvents do not have the degree of brownian motion (My theory) as water. PF can supply the p-aminophenol base. Phenidone is another option, which would make the glycol form of Pyrocat HD. It also is easy to mix.
     
  16. frotog

    frotog Member

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    There's nothing like a tank of nitrogen gas to take the anxiety out of developing negs in pmk.
     
  17. ongarine

    ongarine Member

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    I'm an happy and satisfied user of Pyrocat MC and this suggestion to make a sort of "Pyrogallol MC" is very interesting.
    If I understand well you have to mix, for the Pyrogallol formula, the same amount of catechol + 2/3 of the weight for Pyrogallol formula.
    At the end for one liter of stock solution, as the original formula for Pyrocat MC called for 100 grams of Catechol, it will be 150 grams of pyrogallol to mix Pyrogallol MC.
    Am I right Pat?
     
  18. RobC

    RobC Member

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    Thanks all,
    If understand all correctly, For graded papers I should see no difference between finished prints using either PMK or Pyrocat-HD. The differences are all in the process.
     
  19. noseoil

    noseoil Member

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    " If understand all correctly, For graded papers I should see no difference between finished prints using either PMK or Pyrocat-HD. The differences are all in the process." rob

    Rob, you will see a large difference in the shdow values. Try both to see how they look, then please write back and let us know which types of shadows you enjoy most. After having done both, my hunch is that it will be pyrocat. tim
     
  20. PhotoJim

    PhotoJim Member

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    What would be the advantage of mixing up PMK in glycol? The shelf life is already astounding. Please correct me if I'm wrong, but I understood that the use of glycol was to enhance shelf life of the stock solution. PMK is already near-immortal with plain distilled water. :smile:

    You've given me lots of interesting ideas to try with your posts by the way - please continue :smile:
     
  21. dslater

    dslater Member

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    This is true, However, you can use PMK in a rotary processor quite successfully with a couple of changes to the process - I process FP4+ in a Jobo 1521 tank with the 1509N reel all the time. I have had to make 2 adjustments to get this to work consistently.
    First, use a lot of developer - for me a minimum of 500ml - this is the most I can put in my tank. Second, break up the development time into more than one batch - For example, if my development time is 10 minutes, I'll mix up 2 500ml batches of PMK, start the development with the first one, then after 5 minutes, dump that one out and put in the second batch for the remainder of the time - I find that at 70 deg F, I get the best results if I don't let a batch go for more than 5 -5 1/2 minutes.
    Finally, - I add a very small amount of EDTA to promote even development - this is actually specific to my particular tank and reel - people using the expert probably drums don't need to do this - I got this info from the latest edition of "The Book of Pyro"
    I also don't use the after-bath. It's interesting that even though Gordon no longer recommends the after-bath, it's still in the latest edition of his book.
    I also don't see a lot of general stain on my negatives. In fact, when I got some Pyrocat-HD, I went out and shot multiple negatives of the same subject, then developed some in PMK and some in Pyrocat-HD. When I compare the negatives visually, my PMK negatives don't appear to have any more general stain than the Pyrocat negatives do - of course since I don't have a densitometer and I don't do alternative processes, it is entirely possible that there is more general stain, but I just don't see it visually or when I'm printing.
     
  22. RobC

    RobC Member

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    And this is definitely the case for graded paper? Yes?
     
  23. gainer

    gainer Subscriber

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    No, no! Use 2/3 the weight of pyrogallol in place of the catechol. So, instead of 100 grams of catechol use 67 grams of pyrogallol. Metol and pyrogallol are the only developing agents, not counting the small amount of ascorbic acid.
     
  24. Tom Hoskinson

    Tom Hoskinson Member

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    The easiest way to evaluate image stain (presence or abscence of stain) is with a transmission densitometer. Visual evaluation of the negs can be very
    misleading.

    The second way of evaluating image stain is the Pat Gainer recommendation of bleaching out the silver image - thus leaving any stain image behind.

    BTW, I am a Pyrocat-MC user. Most of my development is with minimal or semi-stand agitation. BTW, I get excellent results with Sheet film. 35mm and 120 roll film as well.
     
  25. Philippe-Georges

    Philippe-Georges Member

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    So, 133 gr. of Pyrocat instead of 100 gr. of pyrogallol will do well too?

    Philippe
     
  26. dslater

    dslater Member

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    Yes - but I was talking about the general stain - not the image stain. My observations on general stain were based on the appearance of deep shadows and the unexposed edges of the film.