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  1. #31

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    The MSDS for Harman Cooltone lists DTPA, Hydroquinone, and Potassium Carbonate. Presumably the DTPA is used to deal with water quality issues. However, would the use of Potassium Carbonate in place of Sodium Carbonate alter print tone?

    http://www.freestylephoto.biz/pdf/ms..._Developer.pdf

    http://en.wikipedia.org/wiki/DTPA

    Tom.

  2. #32

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    Further research on APUG suggests Slavich Unibrom is available in Germany from www.monochrom.com

    Tom.

  3. #33
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    Tom, Ilford and Agfa (and presumably Kodak in liquid Dektol) use Potassium Carbonate often with Sodium or Potassium Hydroxide in place of Sodium Carbonate in liquid developers. A typical Ilford example (Patent reference developer) uses 38.44g Potassium Carbonate plus 2.12g of Sodium Hydroxide per litre instead of 50g of Sodium Carbonate, while a similar Agfa formula uses 15 g Potassium Carbonate and 4g Potassium Hydroxide. It's all to do with the relative insolubility of Sodium Carbonate being the limiting factor of the potential concentration of a commercial developer, and also cost savings.

    Adding Potassium salts instead of Sodium will give very slightly warmer tones.

    If you add Potassium Iodide then Kodak's research was into 1-8gm's per litre of working solution, but the KI has an impact on fixer capacity as Silver Iodide is formed which is relatively insoluble. Kodak were using it in activators with developer incorporated papers to control image colour and induce blue B&W tones.

    Ian

  4. #34

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    Ian,

    Aside from using Potassium Iodide to induce blue-black tones, do you have any other suggestions or formulation approaches to produce blue-black tones?

    Tom.

  5. #35
    Ian Grant's Avatar
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    I'm looking into that at the moment, but I'll be in a better position next week when I can access my reference books.

    A major problem is that Ilford & Agfa used proprietary organic agents to control the cold/blue tone, even if we knew what they are it might be difficult to get the small quantities required.

    As soon as I find something I'll post it here.

    Ian

  6. #36
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    Freestyle offers a liquid concentrate cold-tone paper developer, stating dimezone-s as one of the constituents.
    John, Mount Vernon, Virginia USA

  7. #37
    Ian Grant's Avatar
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    Ilford now use Dimezone-S in some of their liquid PQ developers instead of Phenidone so it shouldn't make any significant difference to the image colour/tone.

    Ian

  8. #38

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    Ian,

    What do you think the effect would be of using say 8g Benzotriazole in the stock solution, translating into 2g per litre of working solution? I suspect the paper would need to be given extra exposure under the enlarger.

    Tom.

    EDIT: Actually, I've tested at 1.5g Benzotriazole per litre of working solution already...

  9. #39
    Ian Grant's Avatar
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    There are too many variables Tom, different papers will behave in different ways, you'd need to try it. I have to admit that most of my research in the past regarding image colour has been predominantly into warm-tone developers and toners.

    Ian

  10. #40

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    First, let me state that I don't really know what I'm doing. But the principles laid out here seemed so clear: for cold tones keep the pH high (within reason), avoid phenolic developing agents, use plenty of restrainer, but substitute potassium iodide and benzotriazole for potassium bromide. It couldn't be that hard. After searching a good many published formulas, I came up with the following and mixed it up using incantations that have proved effective in previous such adventures:

    Sodium sulfite (anh) 15 g
    Trisodium phosphate 40 g
    Phenidone 200 mg
    Ascorbic acid 10 g
    Potassium iodide (1% soln) 5 ml
    Benzotriazole (1% soln) 10 ml

    pH 10.8

    (Sodium carbonatre and sodium hydroxide could probably be substituted for the TSP to get this pH. The TSP I used was a commercial cleaning material, and its hydration is uncertain.)

    I tried it out with Ilford MGIV RC. That paper isn't known for its tonal response with different developers, but oh well. I compared the results with development in D-72. The results were somewhat cooler, although not a lot. This developer obviously needs tuning, since the midtones were decidedly worse than those with D-72. In any case, I was encouraged. I tried the following:

    Metol 3 g
    Sodium sulfite (anh) 15 g
    Trisodium phosphate 40 g
    Ascorbic acid 10 g
    Potassium iodide (1% soln.) 10 ml
    Benzotriazole (1% soln.) 20 ml

    The results were much improved. The tone shifted very significantly toward the blue, contrast was good and reasonable, and the gradation was a lot more like D-72. The principles seem to work, at least from these limited tests. My curiosity was satisfied, so I quit here. But the developers are not really finished. They need fine tuning. Unfortunately, that's hard work.

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