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  1. #1
    erikg's Avatar
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    Any tips for C-41 in a Jobo?

    I'm going to process some C-41 films in my jobo using the Tetenal kit this weekend. It's been years since I've run color. I didn't have the jobo back then either. (CPP) I'm running 120 and 4x5. Should I presoak? Is 100 degrees the best? Any other advice that I won't get from reading the manuals?

    Thanks!

    erik

  2. #2
    DanielStone's Avatar
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    Pre-Heat, don't pre-soak. Run the loaded tank in the water jacket for 10-15 min to get it warmed up, and make sure your chems are tempered well, and stay at a stable temperature.

    38deg C(100F) is what c-41(at least the Kodak and Fuji chems) are designed to be run at.

    -Dan

  3. #3

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    Jobo makes C-41 a pure pleasure. I pre-soak for C-41 and pre-heat only for E-6. Excellent results either way. I was getting drying spots with Tetenal's stabilizer, so you may want to try it on junk negatives first. Switching to Kodak's final rinse solved it. Have fun!

  4. #4
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    Pre-soak, don't pre-heat. An empty drum requires a lower level of water in the water bath to prevent "flotation" due to buoyancy and thus the drum often does not keep warm unless extra water is added later when in use. Also, if the drum does "float" a bit, it stresses the red gasket at the top of the tank near the cog if you have a lift.

    In addition, the core of the drum does not fully heat with just air which has poor conductivity.

    The pre-wet does the job rapidly, and also helps prevent air bubbles. It also aids in rapid wetting of the film with developer.

    PE

  5. #5

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    I've been using the liquid Tetenal kit for six months now, and I've gotten good, repeatable results by sticking with a 5 minute warm up of the tank once film is loaded, no wetting. Make sure the motor is running too of course.

    Then, stick with exactly what is printed in the Tetenal instructions - 3:15 I believe for dev, 4:00 for bleach / fix, and then 4:00 or so for rinsing (I do 6 changes of water - 4 every :30, then 2 more every 1:00). Then I do one more fill with water, add the stabilizer, manually rotate off the Jobo for 1:00, pull and hang to dry.

  6. #6

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    So P.E... can I ask... does the pre-wet affect the development of the film at all? I actually do a pre-wet when I develop black & white, because that way I can stick with the exact timings listed on the Massive Dev Chart. But, I notice that there's an awful lot of "stuff" which comes out of the tank when I dump the pre-wet water, and I wonder if that has any effect on the development of the film? Would I expect to see the same change of color of the water when pre-wetting color negative film, and if so, does that impact the timing of development from what is published?

    Thanks for your help!

  7. #7
    Photo Engineer's Avatar
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    I use the prewet all of the time and have for over 20 years. I have seen no significant difference in the few tests I did run.

    I have done it both ways though, over the years and find better uniformity and fewer defects using a prewet.

    The colored materials that wash out in a prewet have been described elsewhere in a lengthy thread, but basically they do no harm by being washed out.

    Two things to remember. I discard my developer after use. I have tried reusing the developer and found it unsatisfactory to me and that is why. I also use 2 prewets of 30" each as the first one drops in temp quite quickly.

    Also, the 4' wash time is probably not enough. If the stabilizer or final rinse (which I reuse) gradually turns light pink, the blix is getting into it through a poor wash and will eventually harm the film.

    PE

  8. #8
    erikg's Avatar
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    Thank you everyone. This is very helpful. I no longer have a pro lab near by to get quick turn around, so if I can get this down it will extend my ability to shoot film on certain jobs into the future. Seems like it wasn't so long ago we had 4 labs to choose from. There is still a good lab in the Boston area I use, but often I need faster turn around, especially over a long weekend. I appreciate all of your input.

  9. #9

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    Thanks for the info PE, I was using a 5 minute pre-wet with the b&w... I'll try the shorter ones with color (on a test roll) and see how it goes.

  10. #10

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    Quote Originally Posted by Photo Engineer View Post
    I also use 2 prewets of 30" each as the first one drops in temp quite quickly.

    PE
    Great tip, PE. This makes a lot of sense. The temperature can really drop quite a bit with only one prewet, especially if there is a lot of films in the tank such as a roll of 220 film. When I develop manually my prewet water used to be tempered at 105 degree. There was no need of two prewet. But with my Jobo ATL processor this is impossible. It can only be set to whatever the process is set to tempered at, which is usually 100 degree of course. I measured the temperature of the prewet water when it is drained out of the tank. It was usually 2 to 3 degrees lower than 100. Before the developer is poured into the tank the film inside could drop a few more degree again. It really could cause under development as a result.

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