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  1. #11
    Vincent Brady's Avatar
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    I've been developing films for 25 years and never allowed a waiting time between inversions and dump. My negs are still OK. Perhaps the 5 minutes are for the water to remember which end to pour out from.

    Cheers
    TEX

  2. #12

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    Quote Originally Posted by TEX View Post
    I've been developing films for 25 years and never allowed a waiting time between inversions and dump. My negs are still OK. Perhaps the 5 minutes are for the water to remember which end to pour out from.
    Good one!

    Funny, but I think the idea is to allow extra time for dispersion.

    It may or may not be necessary depending on other factors: the types of chemicals used, individual processing procedures, water quality. My approach is to err on the safe side.

    If you have the extra 15 minutes required it certainly wouldn't hurt. Besides, "waiting" isn't exactly a labor-intensive procedure.

  3. #13
    Vincent Brady's Avatar
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    Quote Originally Posted by Kent10D View Post
    Good one!

    Funny, but I think the idea is to allow extra time for dispersion.

    It may or may not be necessary depending on other factors: the types of chemicals used, individual processing procedures, water quality. My approach is to err on the safe side.

    If you have the extra 15 minutes required it certainly wouldn't hurt. Besides, "waiting" isn't exactly a labor-intensive procedure.

    Ken to be serious, I always imagined that the inversions shook up the chemical adhering to the film and was dumped before it had time to settled back onto it.
    As the inversions increased the chemical was being washed off the film even more thoroughly and again you dumped it before it had time to settle back onto it.
    This was my layman's thinking to the 3 changes of water and the increased inversions.

    Cheers
    Vincent

  4. #14
    trexx's Avatar
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    The reason for my post is I help out at a community darkroom. There are often a bunch of new bees that line up to put their tank under the water tap for the ten minutes that is listed on the helper sheet on the film darkroom wall next to all the development times. I would much prefer them to form a conga line of fill invert ( wait for the tap ) and dump, instead of standing on line with empty tanks and fixer drying on their fresh negs.

    I now have something I can take to the, very good but set in his ways, instructor as an alternative for washing
    D-76 is a standard developer, although not one I use.
    Ansel Adams - The Negative

  5. #15
    Steve Smith's Avatar
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    Quote Originally Posted by pentaxuser View Post
    You'd think that Harman would have researched what a waiting period does......
    Or as Roger Hicks once put it: "Why would they tell you to use a method which didn't work?"



    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

  6. #16
    Ian Grant's Avatar
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    Chemicals aren't just washed off a film they have to diffuse out of the emulsion as well, this is why using minimal water techniques requires time for this diffusion to happen during the waiting periods. Even using running water won't appreciably shorten the time for the diffusion to take place.

    Ian

  7. #17
    Martin Aislabie's Avatar
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    Ian, I thought all the Chemicals came out of both film and paper by diffusion after the initial immersion which of course washes off the surface chemicals.

    Doesn't running water only ensure that the largest posible chemical gradient exist?

    Thanks

    Martin

  8. #18
    fotch's Avatar
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    Quote Originally Posted by Steve Smith View Post
    Or as Roger Hicks once put it: "Why would they tell you to use a method which didn't work?"
    Steve.
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  9. #19
    Ian Grant's Avatar
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    Diffusion takes time, some of the silver/thiosulphate complexes are only semi-soluble particularly in a used fixer bath. Sure most of the chemicals diffuse out quickly but the last traces take longer.

    Ian
    Last edited by Ian Grant; 01-30-2009 at 12:18 PM. Click to view previous post history. Reason: typo

  10. #20

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    A detailed survey on this topic was done by Rolf Suessbrich. You may have a look on the pdf with his results which you will find here http://www.largeformatphotography.in...tml#tthFrefAAC together with some comments by Marc Torzynski.

    Ulrich

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