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Thread: using BTZS tubes without expo dev app/film testing

  1. #1

    Join Date
    Jun 2011
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    94

    using BTZS tubes without expo dev app/film testing

    If I were to use the BTZS tubes without the expo dev app/film testing, would the agitation still be same if I followed the development time recommended by the manufacturer?

    In other words, if I dont want to do multiple film testings, and I just want to follow the generic dev time for a given film, can I just use the same agitation while spinning the tubes? I just want to make sure that I wont over-develop by the continuous spinning.

  2. #2
    retrogrouchy
    Join Date
    Mar 2010
    Location
    Adelaide, Australia
    Posts
    801

    Re: using BTZS tubes without expo dev app/film testing

    Tubes require constant agitation to get even development as the tube is not full; if you let them sit still for a minute, you will develop about 1/3 of the film and the rest will be in air! If you can find times recommended for rotary/constant agitation (e.g C41 and E6 assume constant agitation) then use those, otherwise develop for about 10-15% less than the recommended time.

    I find the constant agitation gives a slightly different curve with a little less film speed for a given contrast, so testing is a good idea but plenty of people just use tubes as a dev method with nothing more formal.

  3. #3

    Join Date
    Sep 2007
    Location
    Stevens Point, WI
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    1,487

    Re: using BTZS tubes without expo dev app/film testing

    As a rough guide, use the development times listed for rotary processing.

  4. #4

    Join Date
    Sep 2003
    Location
    Massachusetts
    Posts
    44

    Re: using BTZS tubes without expo dev app/film testing

    In the Jobo processors, Jobo (the company) determined that a five minute pre-wet compensated for the extra agitation from continuous rotation. The result was that the times wound up almost exactly the same as the published ones for tank development with intermittent inversion.

    So, I would recommend following the same procedure. Otherwise, cut the times by 10-15%.

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