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  1. #1

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    C-41 Problem with Jobo expert drum/CPP/Digibase

    Hi all,

    (Long time lurker and have learn't a lot from APUG in the past few months)

    Wonder if anyone could let me know whats happening with these two 5x4 Ektar negs?
    They have come out the 2 separate runs and the other 3 negs in each run came out perfect.
    I'm using a Jobo expert drum with no pre soak and the digibase C-41 kit as one shot, following the instructions as printed, using 250ml dev.
    Rotation is around 50rpm, one way. Can't understand why the other negs are fine and these have streaks across them?

    (I've tried a re-bleach and re-fix)

    (Please excuse rubbish scans, had a long day and yes the ground should be red and the line on the right is some railings)

    Regards
    Ed
    Attached Thumbnails Attached Thumbnails neg1.jpg   neg2.jpg  

  2. #2

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    I do not have solution.

    But I have similar issue when using print drum to develop 8x10. Usually one is ok and the other is not. After listen to PE, I wonder now whether this is due to lack of pre-soak. The negative would face a temperature shock induced by the hot water coming in. Unlike BTZS tube and even for expert drum, one wonder whether the negative can be warm up to the degree of high temp. required by C41/E6.

    Looking forward for other comments to know more.

  3. #3
    Greg Davis's Avatar
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    Are you pouring the chemicals in while the drum is rotating?
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  4. #4
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    Those are developer streaks. The developer is not wetting the film evenly and probably the temperature is not fully up to 100F.

    It may also be made worse by slow (one way?) rotation. (did I read the OP right? One way rotation, not oscillation?) Slow or one way rotation is not good. Jobo listed an updated rotation recommendation quite a few years ago in which the larger the tank diameter, the higher the rotation rate. This is logical. I now use 5 or 6 for the back and forth rotation of my drums.

    You should never use one way rotation!

    A prewet does not hurt. See the thread where someone tested drum temperatures with and without prewet.

    PE

  5. #5
    msage's Avatar
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    I never had this happen to me. I use one way rotation, but I use more solution and always use a pre-soak. Use more solution and a pre-soak.
    Michael

    "I only wanted Uncle Vern standing by his new car (a Hudson) on a clear day. I got him and the car. I also got a bit of Aunt Mary's laundry, and Beau Jack, the dog, peeing on a fence, and a row of potted tuberous begonias on the porch and 78 trees and a million pebbles in the driveway and more. It's a generous medium, photography." -- Lee Friedlander

  6. #6

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    You did not mention which expert drum you are using. Make sure you use enough solution. The 3004 and 3005 require 270ml of solution, so your 250ml of developer could have been the culprit as well if you used one of those.
    Also, I'll second the presoak recommendation, works like a charm.

  7. #7
    DanielStone's Avatar
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    how long are you guys pre-wetting for btw?

    -Dan

  8. #8
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    I prewet with 2 soaks of 30" each with a 7" drain.

    PE

  9. #9

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    Thanks all I'm using a 3006 and slowly pour in the dev over 10 seconds, next run I'll try a pre-soak and hopefully it'll sort out the problem.
    After lots and lots of research (and to easy on the motor) the conclusion was one way was fine, and the results have looked OK to me.

  10. #10

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    I've done my last couple of batches in a Jobo 3010 with the two 30 second presoaks and one-way rotation. Out of 20 sheets I had 1 that developed unevenly. I haven't tried it again yet to see if it was a fluke or a recurring problem. My initial reaction was to blame weak developer (Trebla, not Digibase), since the concentrate bottle had a small yellow chunk that had precipitated out.

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