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  1. #1
    stradibarrius's Avatar
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    processing film question?

    At what point does the film become light safe? After the stop?
    "Generalizations are made because they are generally true"
    Flicker http://www.flickr.com/photos/stradibarrius
    website: http://www.dudleyviolins.com
    Barry
    Monroe, GA

  2. #2
    Steve Smith's Avatar
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    In theory, yes. In practice, it depends on how completely you have stopped it.


    Steve.

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    Even though the film can be viewed for a short time after the stop, the image will degrade in light until it is fully fixed.

  4. #4
    Photo Engineer's Avatar
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    You really should not view the film until it has cleared. You can test clearing time by placing a small piece into the fix and timing how long it takes to become clear. It is not fixed at that time, it is only 1/2 fixed or 1/3 fixed depending on fix, but it is no longer light sensitive under subdued light.

    Before that point, even in the stop, film is sensitive to light and can change slightly.

    PE

  5. #5
    Steve Smith's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    It is not fixed at that time, it is only 1/2 fixed or 1/3 fixed depending on fix, but it is no longer light sensitive under subdued light.
    Which brings up a question I have been meaning to ask for a while:

    Are fixing and clearing two different processes? (from your reply I see they are).

    Can you tell me what is happening apart from the clearing?


    Steve.

  6. #6
    Photo Engineer's Avatar
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    Clearing turns Silver halide into Silver-hypo complexes but these are still in the film and still may brown or darken. Fixing is the removal of these from the film by outward diffusion into the fix solution. However, these terms are very loose. They are imprecise and there is no clear description in human language other than a series of chemical equations. Up to 5 or 6 types of complexes are forming in Sodium Thiosulfate and more form in Ammonium Thiosulfate. These complexes are "clear" compared to the Silver halides which are milky or cloudy.

    PE

  7. #7

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    I've been using a water as a stop bath for my film these days 'cos I run out of stop bath and was in a fix (I should do stand up comedy) to get a roll processed....does a water stop bath require more fixing time than say the stop bath Kodak sells?????.....
    hang on, you're Ron Mowrey who was on Inside Analog Photo Radio in that interview right???.....chapeau...you're a legend....

    Quote Originally Posted by Photo Engineer View Post
    Clearing turns Silver halide into Silver-hypo complexes but these are still in the film and still may brown or darken. Fixing is the removal of these from the film by outward diffusion into the fix solution. However, these terms are very loose. They are imprecise and there is no clear description in human language other than a series of chemical equations. Up to 5 or 6 types of complexes are forming in Sodium Thiosulfate and more form in Ammonium Thiosulfate. These complexes are "clear" compared to the Silver halides which are milky or cloudy.

    PE

  8. #8
    Photo Engineer's Avatar
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    I'm an ordinary guy. But, I have spent my entire life in the photo industry either on the photofinishing side, the commercial side or designing photo products at EK or now privately. Just fun!

    Thanks though.

    But, to answer your question, a stop should always be used for prints, especially FB, and is quite useful for film as well. It does help protect and extend the life of all fixers, even alkaline fixers. A stop can be used with TF-4, as it is so well buffered.

    PE

  9. #9

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    Quote Originally Posted by stradibarrius View Post
    At what point does the film become light safe? After the stop?
    I won't risk my precious (i mean, precious to me) film. Just a few more minutes' waiting wont hurt

  10. #10
    2F/2F's Avatar
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    Quote Originally Posted by stradibarrius View Post
    At what point does the film become light safe? After the stop?
    After clearing. Should take under a minute in fresh fixer. Save your trimmed 35mm film leaders for testing clearing time prior to processing
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

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