Are these light streaks?

Discussion in 'B&W: Film, Paper, Chemistry' started by elerion, Sep 16, 2018 at 4:11 AM.

  1. elerion

    elerion Member

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    I've just developed a test roll to try out a homemade developer based on tea+ascorbic+carbonate, at pH 10.35. (aiming to a Caffenol C-M alternative, which doesn't smell bad). It seems to be strong enough to develop more than one 35 mm roll per 300 ml.

    But, I overdeveloped too much. I did a clip test and the drop test, and guessed a developing time of 25 minutes (25ºC).
    It seemed a slow developer, maybe to weak, and I decided to go semi stand, for one and a half hours (three invertions after 2,4,8,16,32,... minutes). Obviously, the development was faster than initially guessed. Base+fog is 1.9 (!!)

    Also, there're streaks that seem to be due to light. I never saw these before. I was very carefull while loading the film (in complete darkness, from a 30 m roll to a plastic canister I've used other times with perfect results).
    The light area of the streaks fall between the perforations of the film, and, with varying intensity, cover the full length (17 exposures). The most obvious (attached) is not at the beginning or the end, but in the exposures near the middle of the film length.

    I'll be doing some more test.
    Any idea? Thanks in advance.
     

    Attached Files:

  2. glbeas

    glbeas Subscriber

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    My first guess would be bromide drag from the stand process. Try again with much less time and more agitation.
     
  3. WilmarcoImaging

    WilmarcoImaging Member

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    Sprocket marks. How did you agitate? Generally the sprocket marks happen when inversion agitation is too vigorous or frequent. In your example, the lighter areas (higher density on the negative) are the holes. The darker (thinner density on the negative) are the film support. Locally higher developer velocity from vigorous inversion is the explanation.
     
  4. OP
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    elerion

    elerion Member

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    Yes, after searching for bromide drag, this seems the explanation.
    Strange,... I did the most invertions at the beginning, where I've read it is more important.
    I'll try much sorter time and not let it stand for more than 10 minutes.

    Three gentle invertions, with some rotation of the tank between and before each of them.
    Definitely not vigorous.
     
  5. WilmarcoImaging

    WilmarcoImaging Member

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    On the example, 8 intervals of density variation are seen. 35mm film sprocket pitch is about 4.75mm. For a 36mm wide image area, approximately 7.6 sprockets (nearly 8) would be encompassed.
     
  6. Agulliver

    Agulliver Member

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    I have had similar with fogged film. I had a film jam in a camera while away camping and used a dark duffel bag and blanket as makeshift changing bag to get the film out and load another. I ended up with most of the exposures like yours above from mild light fogging. I used standard ID11 inversion processing for this roll.

    Equally it could be bromide drag.

    Is there any chance the film could have been fogged?
     
  7. OP
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    elerion

    elerion Member

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    The streaks do fall between sprocket holes.

    There's always a chance... as I loaded the film from bulk, but I really don't think so.

    Will try again, and post the results.
     
  8. Andrew O'Neill

    Andrew O'Neill Subscriber

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    Bromide drag. It can happen with stand/semi-stand if you're not careful (too much time allowed for the film to just "sit").
     
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