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  1. #11

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    It is, indeed, a very grainy developer. Some may be interested in it just for that reason. I'm not real fond of its rather brooding tonality, but that may be an exposure issue.

  2. #12
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    Quote Originally Posted by Alan Johnson View Post
    Hi Brad,
    Hope you can get an idea of the fog levels with D-76d EI=100 and W3 EI=200 from the attached pics on a lightbox.
    Interesting....and about what I expected. There is noticibly more fog than with D76 but, it does seem manageable. It might be interesting to see what effect the addition of some benzotriazole (spelling?) or KBr has on the fog level.
    Thanks for the scan and the thread.

  3. #13

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    The ratio of dimzone to ascorbate that I have seen is usually 1 to 40 or even higher. All the phenidone derivatives tend to produce fog in highly alkaline solutions without a restrainer. For any super-additive combination there is an optimum ratio for the two developing agents. This ratio is dependent on the composition of the developing. You must take into account the sulfite content. alkalinity, restrainer, etc. Formulating a developer is NOT an easy task. Mason discusses this and shows a graph of effective speed versus the ratio of the developing agents. The curve is U-shaped showing that an optimum ratio exists.
    Last edited by Gerald C Koch; 03-03-2014 at 11:44 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  4. #14

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    Thanks for the suggestions re KBr/Benzotriazole and Dimezone-S.
    But first, to see if the developer has a reasonable shelf life,I am keeping 700 ml of it in a sealed glass bottle with 350 ml airspace and hope to monitor its activity.

  5. #15

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    Before reaching for a restrainer consider Haist's advice: "if you've got too much fog, you've got too much alkali". This may be a better way to imrove overall characteristics as a starting point. You've got a relatively huge amount of carbonate in there for a film developer (and a high pH for any film developer let alone Phenidones). I'd try rebalancing first before adding a restrainer since your goal is a speed increasing developer. All things being equal, a restrainer will tend to reduce speed and increase contrast.

    Another important thing to consider is at this pH Phenidones are not effectively restrained by bromide so you're essentially limited to either Benzotriazole or other more exotic compounds.

    The first thing I think we need here is some sensitometric data. We need to quantify the speed increase, toe contrast/shape and overall contrast relative to the chosen reference developer (D-76). That will help determine the next steps. For example, depending on how much higher the speed is relative to D-76, we may find the "robustness" of this formula can be substantially reduced without a speed penalty, but with improvements in image structure. For a 1 stop speed increase at a high pH, it may also be possible to use Metol instead of Dimezone, which could help with fog, improve keeping properties etc.
    Last edited by Michael R 1974; 03-04-2014 at 09:01 AM. Click to view previous post history.

  6. #16

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    Michael,
    Thanks for those ideas.
    I think there are some relatively simple things not known (or not published) about ascorbate developers and worth looking at,though it is a slow process.
    (1) In absence of sulfite oxidation gives an orange compound which may be dehydrosacorbate and first indications with another developer made from p-aminophenol and ascorbate are that the pH tends to drift lower.
    (2) In presence of sulfite,as in the present W3 developer, I expect oxidation to give a yellow compound, relatively colorless, and it is of interest to find out if the pH still drifts lower or if the sulfite stabilises it.
    For years people have said "Oh ascorbate developer working solution does't keep throw it out after a day"
    I'm not convinced that this is always true but it has to be found by experiment.

  7. #17

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    I think the reported issues with ascorbate developers (the valid reports, at least) may have more to do with Iron ion impurities in the solution, leading to the well documented Fenton reaction which can destroy ascorbate quite quickly. This would tend to be more of a problem with home-mixed developers with tap water, ingredients of unknown purity, and the lack of a sequestering agent. These problems can largely be worked around.

    What is more difficult is the preservation of Phenidones in aqueous solutions, particularly solutions of relatively high alkalinity, as is the case with W3. On the other hand the presence of ascorbate (or other Phenidone-regenerating agents) helps. In Haist there is some interesting information on preparing concentrates with Phenidones with some proposed formulas (mostly based on the work of Axford/Kendall at Ilford), but they are typically two-part formulas.

  8. #18

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    I am concerned with the case of many days/weeks exposure of developer to air in a part full container where the Fenton/ordinary oxidation of ascorbate is probably complete.
    The final products of the Fenton reaction are possibly oxalic and threonic acids:
    http://informahealthcare.com/doi/abs...ournalCode=fra
    The color of threonic acid is probably beige:
    http://www.hmdb.ca/system/metabolite...pdf?1358463319
    I just note this for reference,not claiming this is what happens to oxidized ascorbate.

  9. #19

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    For shelf life, it might be interesting to try to develop a version in an organic base, a la PC-Glycol/PC-TEA/HC-110. Keep the ratios of active ingredients, with some reduction in the carbonate to compensate for the base, and mix in however much glycol or TEA it takes to dissolve them, then dilute at time of use...

    I just did a little bit of googling and found a thread on APUG from 2006, in which a guy named Alan Johnson had a nice discussion with Pat Gainer about adding sulfite to PC-TEA. So you're probably way ahead of me on this line of thought already. :-)

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  10. #20

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    I still think we need to quantify the speed and contrast relative to the chosen reference developer D-76. Otherwise we don't really know what the formula is doing or what direction to move in for optimization.

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