Effects of water drops over undeveloped film

Discussion in 'Color: Film, Paper, and Chemistry' started by Diapositivo, Jun 6, 2011.

  1. Diapositivo

    Diapositivo Subscriber

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    Until now I always gave for granted that in order to develop a film all the tank elements (the tank itself, the reel(s), the funnel) had to be perfectly dry before loading the film.

    This prevented me from executing a second batch of film immediately after the first one because I use a Jobo CPP-2 with "lift" and presently I only have one cog lid. After the first batch I always wash the tank and wait for the day after to process the second batch.

    It was my understanding that water drops on film before pouring the developer would have caused a visible mark.

    Recently I begun pre-washing film. You have already guessed the question, but I will state it explicitly:

    Do I really have to wait for the tank to be perfectly dry before loading it? I understand that some drops of water might fall along the funnel of the lid and reach the film, but is this really so important considering that within a few minutes I'll be pre-washing the entire film in any case?

    I would be glad if you could just dry the tank, use dry reels (I have several of them), dry the lid where I can, don't worry about drying the inner light trap of the funnel and immediately begin the second batch.

    Thanks for the advice
    Fabrizio
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    Fabrizio;

    If you pre-wet film, you don't have to worry about water droplets, but if you do not, a few drops of water can leave spots on the film due to uneven development. And yes, the pre-wet can cause a very very tiny change in the film density, but it is uniform and cannot be seen except by measurement with a densitometer. With drops of water, you can visually see the unevenness.

    PE
     
  3. Ian Grant

    Ian Grant Subscriber

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    Fabrizio, you asked if tanks, reels etc need to be dry, the answer is yes but only the reels unless they are the stainless steel type. Most plastic reels won;t load id wet or even slightly damp.

    Pre-wetting is supposed to stop air bells but when I did some tests 3 years ago I found air bells can form at any stage in a process cycle regardless of a pre wet or not, they occur in dev, stop, fix and washing.

    Ian
     
  4. Diapositivo

    Diapositivo Subscriber

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    Thanks for your answers. This will simplify my processing a lot!