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  1. #1
    BradS's Avatar
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    Why so much Sulfite?

    Why do so many B&W film developers contain so much sulfite? Is it because, historically, devs like D-76 (with 100g/Liter) were used in replenished deep tanks?

  2. #2
    Photo Engineer's Avatar
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    Sulfite is a preservative and mild solvent which gives better image quality.

    PE

  3. #3
    BradS's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Sulfite is a preservative and mild solvent which gives better image quality.

    PE
    Well, yes. I understand that but, wouldn't 25 or 30 g/Liter be sufficient to preserve a liter of D-76 or D-23 if the solution is to be used one shot?

  4. #4
    Photo Engineer's Avatar
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    Make one up and test it. Seeing the results might explain it better.

    PE

  5. #5
    BradS's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Make one up and test it. Seeing the results might explain it better.

    PE
    Point taken. Will do. Thanks.

  6. #6
    Anscojohn's Avatar
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    Brad,
    The sulfite in D23 has multiple functions, as others who know photochemistry can better tell you. My understanding is that it is a real triple threat: preservative, alkali source, and silver solvent. Although I know little about photo chemistry, D23 has been my film developer of choice for many years and I know that some people dilute the stock 1:1, which would give 50 grams per liter. I think it can even be used 1:3 which really get's the sulfite content down there. Once diluted, though, it should be used and thrown away. I SUSPECT that mixing stock with less than the 10% solution would not keep very long--but I would rely on chemical experts, which I am not. I know for a fact that D23 stock lasts a long time in a tightly sealed bottle. I found some unused D23 not long ago--mixed up in 1999--it still worked fine when I tested it.
    John, Mount Vernon, Virginia USA

  7. #7

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    If you're looking for (and I'm not sure of the point of your question) a dev with less sulfite, Anchell's "Darkroom Cookbook" has several.

  8. #8
    BradS's Avatar
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    hmmm, yes. What is the point of my question...well, I guess....it all comes down to the desire to reduce the cost of a liter of homebrew D-23 (or, something like it).

    I have been using D-23 on and off for about a year now and, I keep thinking about the cost of a liter. The simple fact is that a liter of home brew D-23 costs a little more than a liter of pre-packaged Kodak D-76. Since I have a pound of Metol and I like D-23, I'm going to keep mixing my own but, I look for ways to reduce the cost while still maintaining the quality...

    In prior experiments, I've reduced the Metol to 3g / liter and the sulfite to as little as 75 g/liter with good results but, I want it to be less expensive still.

    In another thread, I asked about the Hydroquinone in D-76...with much the same motivation. I think that some of the motivation for the Hydroquinone in D-76 is to reduce the cost (the manufacturer's cost that is).

  9. #9
    Anscojohn's Avatar
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    Brad,

    DK25R.

    John, Mount Vernon, Virginia USA

  10. #10
    David A. Goldfarb's Avatar
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    You need a certain concentration of sulfite in the working solution to get the solvent effect. I forget the percentage, but I think Anchell mentions it in _The Darkroom Cookbook_, and I know it's in Haist, but my copy of Haist isn't handy at the moment. This is why a developer like D-76 acts like a solvent developer and produces finer grain at full strength or 1+1, but produces coarser grain and higher acutance at 1+3.

    If you reduce the sulfite with D-23, I suspect you'll get the same effect--more grain, more acutance.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

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