Spiral problems

Discussion in 'B&W: Film, Paper, Chemistry' started by formPhotography, Jan 6, 2009.

  1. formPhotography

    formPhotography Member

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    I would appreciate some help with a problem I have when using plastic spirals. On a roll of ten 6x7 film I have a dark band on the eighth negative, always within a little in the same place. I have considered all sorts of possibilities, and have come to the conclusion that the end of the film is curling in and touching another part of the film (ie where the 8th negative appears).

    None of my personal contacts have encountered this, and I've so far been unable to find anything on the internet. Does anyone have experience of how to overcome this? I am unable to post a scan.
     
  2. archphoto

    archphoto Member

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    It could be the way you load your spiral: the emulsion should face the centre of the spiral;
    the film should be competely in the spiral;
    when agitating turn the spiral both clock AND ani-clock-wise.

    Hope this helps,
    Peter
     
  3. mpirie

    mpirie Subscriber

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    Hi,

    The natural curl of 120 film (when loaded with the curl towards the centre) would have the end touching the back of frame 8.

    This wouldn't affect the emulsion side, only the back and anti-halation layers. Even then it'd be very small area. When you remove the spiral from the tank with the film still loaded, do you see the curl touching the back?

    Are you sure you don't have a light-leak or fogging from somewhere?

    Mike
     
  4. DavidM

    DavidM Subscriber

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    Hi
    A couple of things to consider or try.

    When loading the film try giving the reeel 3 more turns to feed the film into the reel further.

    Load the film into the reel from the end rather than the begining (last frame) , I find that this can be a bit easier to load on some tightly curled films.

    Have you tried other reels ?
    Do you cut the corners of the film off prior to loading ? - if so try a roll without doing this

    Regards
    David
     
  5. Martin Aislabie

    Martin Aislabie Subscriber

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    I have never heard of this problem or no anyone who has had it either

    But - do you load the film onto the spriral so that the end of the film is a couple of grooves into the spiral

    If you don't get the film fully on the spiral is can flop about and contact the film on the next groove in

    With a little light pressure from your thumbs as you ratchet the spiral back and forth you can "walk" the film further onto the spiral

    I assume you are loading the spiral emulsion side inwards - with the natural curl of the film

    Martin
     
  6. formPhotography

    formPhotography Member

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    Thanks for the replies Peter, Mike and David. My first thought was that it was caused by a light leak, but this was happening with two different Mamiya cameras, so couldn't be in camera, and given the shape - a vertical band that doesn't extend into the rebate - it was difficult to see how it could be a leak during processing. Initally it was happening in about 90% of processed film. Having tried a number of things, I by chance noticed that the film was touching when I undid a spiral. I tried loading the film from the other end, only for the band to appear on the 3rd frame. Finally I tried cutting the corners off the leading edge, which has vastly improved the situation. The number of affected films has probably now reversed - down to 10% - 15%, and the marks are more faint. However this hasn't eliminated the problem, and interestingly, where a mark is visible it's now in the shape of the cut end!!

    I am trying to load the film very slowly and carefully. I've tried to identify a problem with particular reels, but there doesn't appear to be any correlation. I haven't tried loading the film further into the reel, as suggested by David, and will give this a try.

    In the meantime thank you for your suggestions. I am running out of ideas.
     
  7. formPhotography

    formPhotography Member

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    Martin - thanks for this. I was typing my first reply as you were posting.

    I insert the film so that I push it just beyond the ball bearings. I have tied pushing it a bit in, but usually I then ratchet the reel back and forth as normal, with my thumbs helping where necessary and acting as a guide. Yes, I'm loading with the natural curl of the film. Someone suggested I try it upside down, but I found this to impossible.

    Steve
     
  8. archphoto

    archphoto Member

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    Dumb question maybe, but do you cut off the paper sticker that holds the film to the paperbacking ?
    I allways did en never had this problemm.

    Peter
     
  9. trexx

    trexx Member

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    A question, do you remove the tape from the end of the film? There may be a minimal light leak in the tank, raising the base fog uniformly, except where it also reflects off the tape.

    I remove the tape normally because it can absorb fixer more so then the film and I am concerned with contamination after drying.

    TR
     
  10. fotch

    fotch Member

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    If I understand what you said, it seems to me you have just pinpointed the problem to be the reel, nothing else. If you have a different reel/tank system, like Stainless Steel, and in using it the band disappears, this would confirm the finding.

    Good Luck
     
  11. formPhotography

    formPhotography Member

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    A question, do you remove the tape from the end of the film? There may be a minimal light leak in the tank, raising the base fog uniformly, except where it also reflects off the tape.

    I've just processed five films and cut the end tape off: none of the films show the band/marks. I'll keep trying this - thanks TR and archphoto

    If you have a different reel/tank system, like Stainless Steel, and in using it the band disappears, this would confirm the finding.

    Thanks for the suggestion Fotch. I've recently bought a small stainless steel tank in case I couldn't solve the problem, but all my big tanks are the Paterson system 4, so I'd rather try to solve it if possible. Nobody else I've spoken to has come across the problem, so I assume it's something I'm doing.

    Steve
     
  12. mpirie

    mpirie Subscriber

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    Steve,

    If the tape ends and markings correlate, then you're clearly on the right track.

    But what a bizarre situation to have a light leak reflecting off of the leader tape and causing localised fogging!!

    What are the chances of this occurring? You'd need to have the spirals in the exact same location each time in relation to the light leak.

    Mike
     
  13. formPhotography

    formPhotography Member

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    I've processed some more film, again without problems. I am wondering, in light of the fact that at one point the marks took the shape of the cut end of the film, whether developer was being held longer where the film touched in the reel at the 8th frame. Anyway, thanks to all who replied; I'm hoping the solution will be permanent.

    Steve
     
  14. MattKing

    MattKing Subscriber

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    Steve:

    The problem with this analysis is, as I understand it, the film is not touching the emulsion side of the film, but rather it is touching the back of the film stock.

    Matt