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Thread: PMK and open sky blotchiness

  1. #1

    PMK and open sky blotchiness

    I've been using PMK for decades now, and I love the results I get with HP5 and Tri-X. I don't have any problems with roll film processed in PVC tubes with a Unicolor, Uniroller; however, with sheet film (4x5 11x14), I often have trouble with hot edges and blotchy skies.
    I started using PMK after reading Gordon's book, and have generally stayed with that technique ever since. In the case of my sheet film, I think it's pretty obvious that the problem is me my technique. In almost all processing issues, agitation is the culprit, so I suspect the difficulty lies somewhere, somehow in the developer tray. I'm using standard tray technique, but clearly something is amiss. I'll briefly outline my methods, but what I would really appreciate is more information regarding PMK sheet film processing in open trays.
    I start with a 5 minute pre-soak that includes a bit of baking soda to prevent film sticking together (I should add that I use highly filtered, untreated, hard water). I transfer the sheets, one at a time, into the tray, rarely, if ever, processing more than six sheets at one time. Once all the film is in the PMK, I shuffle the stack constantly, generating the equivalent of moderate agitation. I gently (to avoid hot edges, that I'm getting anyway) rotate the stack 90 every minute, or so. My standard time for HP5, exposed at 160, is 14 minutes. Additionally, as per advice from this forum, I add small, measured amounts of photo grade, sodium sulfite to the standard PMK dilution. Following the developer, the entire stack is transferred into a running, plain water, stop-bath for 1 minute. Fixing is done with T-4 for 5 minutes. Obviously, however, the problems are occurring in the developer, not at any time afterward.
    I know so many people who employ PMK without any issues, I know it's me, and I DON'T want to change developers. Although, I used HC-110 for twenty years without any similar problems. But after moving to PMK, I'd really like to stay where I am.
    Without open sky, I don't have any problems, other than the occasional hot edge issue.
    I was actually trained as a biochemist (BFA/MFA came after the BS pun intended), so I know how to manage the purity, storage, measurement, and temperature control of chemicals. Laboratory skills aren't part of the problem.
    So please, would someone give me a tutorial on agitation with PMK? I have seen the problem, and it is me!

  2. #2
    Drew Wiley
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    Re: PMK and open sky blotchiness

    Are the sheets emulsion up or emulsion down in the tray? (Emulsion-up has lower risk of air bells). I don't use any baking soda; the carryover would seem to change the working alkalinity somewhat. And no additional sulfite. HP5 always has a bit of perimeter fbf issue because it's a semi-thick emulsion. I use a real stop bath, but it can be weak, around 1/2%. Water rinse alone might be part of the problem. If you're worried about acidity carryover into the TF4, just use an optional plain water rinse after the stop itself. I've never had blotchiness with HP5 in PMK, or with any other film for that matter, after decades of use. I did get air bell issues at the very beginning of my learning curve, and a few streaks due to improper technique way back earlier, before I ever heard of pyro. I use an oversized stainless try with a dimpled bottom, and gently shuffle through the stack plus one every 30 sec; for example, if I have four sheets, I shuffle five, to prevent the same sheet from being on the top of the stack each time. And for each shuffle, the entire stack is rotated 90 degrees so that a different side is lifted each time.

  3. #3
    Barry Kirsten's Avatar
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    Re: PMK and open sky blotchiness

    Scott, two things stand out for me: (i) I have never developed with PMK at 160F which is about 70C. Is this your real developing temperature? (ii) I never tray develop more than three sheets at a time because I don't feel competent to give them all identical treatment or to keep them safe from damage. I know many people routinely develop 6 or more at a time, but I don't. I can well imagine that if I were trying to shuffle six at a time some of my bare sky areas would come out blotchy due to uneven development, which is what your problem sounds like to me.

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    Re: PMK and open sky blotchiness

    Tray size? If not large enough it can be part of the hot edge problem.

    Does the problem with uneven skies/continuous tones show if you process only one sheet of film?
    "My forumla for successful printing remains ordinary chemicals, an ordinary enlarger, music, a bottle of scotch - and stubbornness." W. Eugene Smith

  5. #5

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    Re: PMK and open sky blotchiness

    Quote Originally Posted by Barry Kirsten View Post
    Scott, two things stand out for me: (i) I have never developed with PMK at 160F which is about 70C. Is this your real developing temperature?
    I think that's the iso he exposes at. the emulsion would also likely slough off if it was 70c, and would be pretty toasty for hand shuffling in trays
    notch codes ? I only use one film...

  6. #6
    Drew Wiley
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    Re: PMK and open sky blotchiness

    Risk of edge frilling generally begins above 75F; 70C would turn it into gelatin ramen soup.

  7. #7

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    Re: PMK and open sky blotchiness

    Ha,... The 160 was film speed/E.I., not developer temperature. The "" was unnecessary and maybe misleading; likely confusing the DIN designation in degrees with the ISO-style.

    Anyway, to the issue. I use PMK almost exclusively now and have overcome the unevenness problems associated with this particular developer fairly well. Here's my take, in no particular order.

    Hot edges are caused by turbulence/swirling around the film edges usually when the film is pushed down into the developer. Try using a gentle see-sawing of the film down into the developer after placing the sheet on top of the stack instead of pushing it straight down (that's what I do). The more randomly and evenly (and gently) you can submerge the film in the developer, the better your results will be.

    I get "hot edges" sometimes from in-camera flare and reflections from the beveled edges of the film holder and the inside of the camera back. I fight with this regularly. Blacking things out with flat black paint and roughing things up with fine sandpaper helps, but sometimes it creeps back for reasons I can't ascertain. So, maybe some of your problem is not development.

    I've begun to simply rotate each sheet 180 (not temperature ) with each shuffle. I think the actual action of turning the sheet before re-immersing helps with the evenness and breaks up the drip direction on the neg. I develop 4x5 in deep 5x7 trays (Paterson) emulsion-side up and shuffle the film along the short axis, pulling a sheet from the bottom, rotating it 180 and re-submerging. I go through the stack once every 30 seconds for the first half of development and then once a minute for the second half.

    The initial immersion in the developer is critical to get even skies, etc. I use a water pre-soak (nothing added) for minimum three minutes. I then fan the sheets out in my hand like a hand of cards and, starting from the bottom, immerse the sheets one-at-a-time into the developer, sumerging gently and agitating with a see-sawing motion for whatever shuffle interval I'm going to use (e.g., with 6 sheets, each sheet gets agitated for five seconds). When I immerse the next sheet, I don't push it down tightly onto the sheet below, but agitate the sheet above the sheet below, which gives some more agitation to the previous sheet. So, if I immerse in five-second intervals, each sheet really gets 10 seconds of continuous agitation in the first 30 seconds of development. After all the sheets are in, I begin shuffling, pulling a sheet from the bottom, rotating and re-immersing (gently).

    I still get the occasional hot edge (more with TMY than TXP for some strange reason...) but only rarely now. Skies are nice and even.

    Hope this helps,

    Doremus

  8. #8

    Re: PMK and open sky blotchiness

    IMHO there is absolutely nothing wrong with your technique, your choice of film or your choice of developer. I feel it is singularly how you are executing your process.

    My reference point is many years of experience in using ABC pyro and developing sheet film in 8x10, 11x14, 8x20 and 12x20. Yes, years ago I went through the same angst with using pyro particularly with pale skies mottling causing artifacts (more so than "hot edges") but I can easily see how it can happen. In doing my research on the issues I was having I came across some facts that helped me out considerably. First and foremost we should remember that pyro is an acidic developer that is highly active and that needs to be carefully taken into consideration. I also read that Edward Weston would significantly dilute his pyro (as well as increasing the pyro concentration slightly) and only develop two sheets in a single tray when he had an open/ pale sky and that worked for me. I always tray develop a full size above the negative size I am processing as the first 20-30 seconds of development are absolutely critical that the negatives are constantly moving when you have an open sky in your image. If negatives are not moving or are in contact with each other in the center that could explain the hot edges. You can't effectively do that with more than a couple of sheets starting out as doing more sheets takes some practice. For the last 12 years I process all of my sheet film with an IR monocle and two external IR light sources (not one on the monocle itself) and being able to see the sheets in the tray as I am shuffling through the entire process is the boss. As a result I would suggest you do a process run with only two sheets and if your normal development time is in the six to seven minute range I would consider a slight developer dilution to get into the 8-10 minute development range and that would take a bit of the "pressure" per se off of the initial 60 seconds of development time.

    Bottom line is folks have been tray developing PMK and other pyro developers with great results for many years. We need to get you in this category.

  9. #9

    Re: PMK and open sky blotchiness

    Hey guys thanks for all the responses. To address a couple of the thoughts raised, I'm using dimpled Cescolite trays. For 8x10 I use 11x14 trays and for 11x14 film I use 18.5x14. I'm also employing more than enough developer solution by square inches of film.
    Regarding the use of baking soda, or sodium bicarbonate, it is a base that has a pH of around 9 and is used in extremely small amounts. The small amount in such a large volume of water means that it doesn't really have the ability to alter the pH of any developer in the quantity we typically use. But it does act as an effective barrier that prevents film substrate from sticking together when one surface is wet and the other dry. So the point is well taken, but I doubt it has any effect on the developer.
    I'm processing with the emulsion side up, and managing the film in the developer with smooth, rhythmic movements, nothing too quick or violent.
    Also, sorry about adding the degree symbol my mistake. But as you figured out, I was referring to the ASA I shoot with, not developer temperature.
    One point that does interest me is that I've never kept track of how many sheets per batch I've processed. I develop what I have in groups of six or less until all exposed sheets are finished. Of course, it could be that the problems are more pronounced with larger numbers of sheets, but I don't have such records.
    Just to maintain shuffle/agitation timing, if I have only one or two sheets, I add exposed, processed blank sheets so that I always have a minimum 4 pieces of film in the batch. I don't think I've ever processed only one or two sheets at a time.
    And, just as aside, I too have had problems with interior camera reflections screwing up exposures. To deal with it, I did the same thing you described: painted surfaces flat black, and even had to put black felt on a surface in one of my Wisners to stop it from reflecting into the film in specific conditions.
    From what I know about the chemistry of the film development process, I think the problem, most likely, occurs somewhere in the first minute in the developer, probably being linked to initial submersion and agitation. Still I'm not sure how to successfully address the situation.
    Thinking more about the issue last night, I decided to make a note of all sheets that include open sky and process them separately. I don't know that it will do any good, but at least I'll have a better baseline for comparison.
    Thanks again, Scott And any further thoughts will be greatly appreciated.

  10. #10
    Drew Wiley
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    Re: PMK and open sky blotchiness

    Filtered water? All it takes is a tiny little "seed" of something almost invisible even under a loupe to create a tanning halo; but that looks more like a little zit rather than blotchiness.

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