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  1. #1
    David Lyga's Avatar
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    using baking soda as a restrainer

    Instead of using benzatriazole or potassium bromide as a restrainer for age-fogged paper, I sometimes use sodium bicarbonate (baking soda). I use, for a working solution of Dektol, about 10 to 20 grams per liter.

    Has anyone else 'discovered' this or am I amiss in comparing this with the 'real' restrainer (i.e., benzotriazole or potassium bromide)? I do find that it works quite well, however, and it will be interesting to see if anyone has tried this before. - David Lyga

  2. #2

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    The bicarbonate ion does have weak restrainer capability. However at 10 to 20 g/l of working strength solution you may be seeing a significant lowering of the pH which would retard development. Remember sodium bicarbonate is an acid salt and would create a carbonate/bicarbonate buffer system.
    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

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    It may also be worth mentioning - assuming I'm remembering this correctly - that benzotriazole and bromide don't work the same way as restrainers.

  4. #4
    David Lyga's Avatar
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    Michael R, that is true. The BZ gives a blacker tone than the bromide does.

    And, G Koch, true that the baking soda slows down development, but I have found no further slowing than normal restrainers do. - David Lyga

  5. #5
    Ian Grant's Avatar
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    Adding benzotriazole cools a paper/developer combination, additional bromide makes it warmer but needs increased exposure as the bromide levels increased.

    Ian

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    Mike Wilde's Avatar
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    David Vestal in his seminal (at least to me 'The Craft of Photography' - it is what I learned from in my small town library of my youth) talks about manipulating the performance of a Dektol like developer by manipulating dilition, as well as adding stock solitions of potassuim bromide to warm, which I use, and sodium carbonate, which I rarely do, to up the pH and thus increase contrast.

    The added carbonate trick I surmise was more valuable when there was a lack of quality MG papers in the market at the time of it's writing. I find it easier to change a half a grade up when a print is a tad too soft in it's base exposure, than to swish up a contrastier developer mix just for that one print.
    my real name, imagine that.

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    I have to make the point that the effect of bicarbonate ion as a restrainer is rather small. The only developer that I remember using it was one of Crawley's FX series of film developers. Since BZT and KBr are so cheap I really don't see the need for it in paper developers.
    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

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    I suspect that most of the change you see by adding bicarbonate comes from lowering the pH and buffering, not any restrainer activity. Restrainers have quite different behavior than accelerators (alkalies).

  9. #9
    David Lyga's Avatar
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    You know, nworth, I also thought, initially, that the baking soda would simply 'slow things down' and not contribute to the effects of a contrast increase by suppressing the 'toe' area. But, instead, I have found it to really work as a restrainer. Perhaps this is wishful thinking on my part (maybe you and Gerald Koch are correct) and I certainly would like to hear either agreement with me or more counter-argument. I need to know more about this, either here or in the future.

    Mike Wilde: when Craft of Photography first came out I devoured it and liked Vestal's daring and 'obstinance' with challenging standardixed methodology. - David Lyga
    Last edited by David Lyga; 11-29-2012 at 09:16 AM. Click to view previous post history.

  10. #10

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    I haven't been able to find much on using bicarbonate as a restrainer. Geoffrey Crawley in the formula for FX-2 was very insistent on using potassium carbonate sesquinydrate instead of the anhydrous salt. His reasoning was that the sesquihydrate contained a small amount of bicarbonate that was necessary for the developer to work correctly. He used sodium bicarbonate directly in the formula for FX-55. The developing agent Edinol was described as being so sensitive to restrainers that sodium bicarbonate could be used instead of potassium bromide. Old carbonate developer formulas often included a small amount of potassium metabisulfite which formed bicarbonate ion in situ. Mason and Glafkides make no mention of it.
    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

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