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  1. #11
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    In USP 3,706,561, we comment on secondary ligands helping the blixing reaction in color films. It is well known that borate ion gives an assist in both blixing and bleaching by acting as a complexing agent or assisting in the complexation reactions going on. This is explicitly claimed in the patent.

    This effect is probably used in TF-4, through the use of a high level of borate ion. So, TF-4 might be considered as falling into a multitude of fixer classes including a ternary mixture of fixing agents and being alkaline and being a swelling fix. Although I have tested only the activity in blixes and bleaches, borate may be active in a superadditive manner in TF-4. I don't really know. But, in any event, it is quite probable that it is doing some degree of boosting of the fix reaction.

    I know that almost all early acid fixing baths used borate to help buffer them. Our work with bleaches and blixes often used borate, and we found significant acceleration of the reaction by their presence. Unfortunately, we found no references, nor did we run tests of the effect of borate on fixation alone.

    This is one of the blind spots we see throughout the photographic literature that will continue to compound as the experts in the field pass on to the big darkroom.

    PE

  2. #12

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    Quote Originally Posted by Photo Engineer View Post
    ...what this means is that washing is dependant on time in the wash water, the amount of water used, the amount of fixer building up in the water and the amount of exchange rate of water at the surface of the thing being washed.

    This may go against many practices and in fact may refute some posts here but is stated by Mason from Ilford and Mees and James, both from Kodak. And, this information refutes the Ilford wash method by one of Ilford's respected researchers.
    So... what are you recommending for a wash method?

    What I've been doing is washing 10 5x4 sheets in a Jobo 3010 drum, four washes of 500ml, with times of 1, 1, 2, 4 minutes.

    Based on what you are saying, I can't tell whether I'm OK or should be adding 1) extra washes, 2) longer wash times, 3) more water in each wash cycle, or some combination.

    The real answer of course is to run the two tests. I guess I'll have to break down finally and do the work

  3. #13
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    Bruce, if it tests ok with the two tests for hypo and for retained silver halide, you are ok probably. I don't want to start this mess all over though.

    The Kodak wash method is tried and true and backed by copious data, and is supported by Mason in his textbook and by Mees and James with more information. All seem to agree that washing in changes of water with some sort of flow or agitation is best. If there is no flow, there should be agitation, with changes and some residence time in the water to allow diffusion to take place.

    PE

  4. #14
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    An important reminder on washing

    When you wash film or paper, do you see any fine bubbles on the surface of the material? If so, this is just like the formation of air bells or air bubbles in the developer.

    The bubbles prevent the wash water from reaching the surface of the film, and therefore washing under each tiny bubble is not being as effective as it could be.

    This can lead to a keeping problem, so I remind you all to make sure somehow that these bubbles are continuously broken up. Agitation or changes of water are one way to do this. Both are better.

    PE

  5. #15

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    Quote Originally Posted by Photo Engineer View Post
    Bruce, if it tests ok with the two tests for hypo and for retained silver halide, you are ok probably. I don't want to start this mess all over though.
    Gotcha. I just spent a couple of hours going through the "other thread." OK I had lunch around page 10 I had no appreciation for how complex an issue this is. Clearly, the only way to know is to do some testing. Just like we have to do our own EI testing, we also have to do our own wash testing.

    Why guess if you can know, eh?

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