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  1. #1

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    Production Darkroom Troubleshooting - Streaks and Related Anomalies

    Hello fellow enthusiasts,

    I work in a production black and white lab where we process anywhere from 40-60 rolls of customer film at a time. We're dealing with varying brands, speeds, and a healthy mix of 35mm and 120. We have a workflow set up that batches films with the same processing time together in the same tank. Our tanks vary in size from 8oz to 56oz, all stainless steel tanks and reels.

    Lately, we've been noticing some uneven development on the film coming out of the darkroom, especially in large even midtone areas like skies and sand. We've included a sample image (from a customer roll, 120 6x9) that depicts the phenomenon in question.

    Our current process is as follows:

    All at 68 degrees Fahrenheit:

    1. Pre-Rinse in H20
    5 minutes. Agitating for first 30 seconds, and then 5 seconds every minute.

    2. Develop in Xtol (stock) or Rodinal (1:25 or 1:50)
    Time varies by film. Agitating for first 30 seconds, and then 5 seconds every minute.

    3. Water Stop in H20
    30 seconds, constant agitation.

    4. Fix in Ilford Rapid Fixer (1:4)
    5-7 Minutes. Agitating for first 30 seconds, then 5 seconds every 30 seconds.

    5. Hypo Clear in Perma Wash
    1 minute, constant agitation.

    6. Wash in H20
    30 Minutes, running water bath.

    7. Final Rinse in Photo Flo 200
    Dip & Dunk Each roll individually.

    8. Air Dry

    We would love to hear any and all suggestions about what to try to get rid of these marks. If anyone can figure it out, it's the folks around here.
    Attached Thumbnails Attached Thumbnails BWstreaking_websize.jpg  

  2. #2
    zsas's Avatar
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    Sorry to hear!

    One thought, I once read somewhere someone say something to the effect of the below re prewash:
    "show me a b/w film that says prewash before dev"

    Could that be it?

  3. #3
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    A few questions and a comment...

    The prewet is OK but a little long. Why is it 5' and has it changed?

    Is the rinse after development in running water or standing water?

    Did anything change recently?

    And a comment.... Except for size, those marks remind me of finger prints with dirty fingers. But on a 6x9 they are too small to be that. So........ I got nothing yet unless someone has very dirty or oily fingers.

    PE

  4. #4

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    2. Develop in Xtol (stock) or Rodinal (1:25 or 1:50)
    Time varies by film. Agitating for first 30 seconds, and then 5 seconds every minute.
    I don't know about Rodinal, but X-Tol and most B&W film developers work best with 5 second agitations every 30 seconds after the initial 30 seconds of continuous agitation.

    See page 3 here:

    http://www.kodak.com/global/en/profe.../j109/j109.pdf

  5. #5

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    I don't know what to make of the pattern - I've not seen it before, and I can't really tell if the problem is over development in some areas (lighter values in the positive) or under development in others (dark areas). It's hard to know what a perfect neg would have looked like.
    One thing, though, about 120 film - in my experience, I do much better with evenness (including surge issues) if I agitate longer during the agitation time, then extend the interval (non-agitation time). It's as if the unevenness happens during agitation cycles, not when the film is still, and in order for the fresh developer to exchange all the way through the reel, it needs more agitation time. I also have found that gentle (but thorough) agitation helps minimize surge (which is not your problem, but thought I would mention it). My agitation period for 120 film is at least 15 seconds, whether every minute or every 3 minutes.
    Also, FWIW, I get much more even agitation from HC110 (1:60 or more) than with Rodinal, time and time again. I've almost given up on Rodinal with 120 film, which I don't get, but there it is.

  6. #6

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    Was that roll from a multi reel tank or a single? Also with a long prewet and not enough agitation, you could have areas of the film that have a diluted developer on the surface.

    Oddly that frame almost looks like water vapour in the air accentuated by a red filter.

    Are you replenishing your Xtol, or. . . . . ?
    Bob

  7. #7

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    Never prewet. Ilford warn against it. Kodak does not tell you to do it except for hand interleaved sheet film.

    You have a problem either from prewet or improper/insufficient agitation in developer or possibly fix. Badly fixed film can be refixed and repaired.

    99.9% of these problems are agitation problems.

  8. #8
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    PREWET! PREWET! PREWET!

    It improves uniformity and it reduces the chance of air bubbles! This is based on over 60 years of hands on darkroom experience, 32 of which were in the Kodak Research Labs.

    PE

  9. #9
    artonpaper's Avatar
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    I never prewash. I've been processing for well over 40 years. I read that one should never prewash with X-Tol. In addition, most streaks and stains come from contamination. The reels must be clean before processing. At Brooklyn College we now have the students fill, shake and dump their tanks 3 times with water between all chems. They get clean-as-a-whistle film.

  10. #10
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    Just my guess...

    First, I would cut the prewash time down to a minute. Although time isn't critical, I think five minutes is too long. Cut it down to one minute, maybe two at maximum.

    Second, I would use a stop bath instead of plain water.
    I'm not complaining about the use of plain water as a stop bath. Sometimes, I use water too. But, in this case, I think you're in a special situation.

    If you have several reels of film, stacked up in a tank, you've still got development going on while you're pouring liquids out of and into the tank. Basically, you've got developer dripping down from the reels above which is still acting on the film, still developing.

    It takes me ten seconds to empty a two reel tank. I'm pouring my stop bath in just as the timer beeps. A four reel tank will probably take twice as long and a six reel tank will take three times as long. Right?

    If I'm right, that amounts to thirty seconds where developer is dripping off the film, still developing.

    With so much volume to empty and refill, I think you need to do what you can to stop development as quickly as possible. Every second counts. Only an (acid) stop bath can do the job efficiently.
    Randy S.

    In girum imus nocte et consumimur igni.

    -----

    http://www.flickr.com/photos/randystankey/

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