help from chemistry experts.

Discussion in 'B&W: Film, Paper, Chemistry' started by ann, Nov 23, 2004.

  1. ann

    ann Subscriber

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    Basically what is the major difference between using Sodium thiocyanate vs potassium thiocyanate in GP_1 gold protective solution?

    As some of you know i have been trying to find a replace for Fotospeed commerical gold toner.

    I thought i would try this formula. I have been using GP-1 as split toner with selenium, i.e. Jonathan Bailey's formula.

    I talked with the Photoformulary and they suggested GP-1 over the 231 toner.

    In Steve Ancells"s book the Darkroom Cookbook his formula indicates using sodium thiocyanate or one can use an equal amount of potassium thiocyanate.

    One is twice the cost of the other. So if money is the issue it is clear; however , is there a big difference in the results?
    I have the gold and i have some sodium thiocyanate already on hand, which i will try. Just curious if the results may be better if i order the potassium thiocyanate.
     
  2. Mark Layne

    Mark Layne Member

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    Ann
    There is an excellent formula for gold toner in Tim Rudman's Toning book- everyone deserves this book incidentally.
    I loaned my copy but expect it back today. I don't think it calls for potassium thiocyanate
    Mark
     
  3. ann

    ann Subscriber

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    i know, i have it myself.,
    He suggest ammonium thiocyanate. or a substitute of either of the below.
    I just really need to know about the difference between potassium and sodium thiocyanate if there is any. Or even the differences between all three.

    Since i am not a chemist nor do i want to make up three different gold toners i am trying to determine which of the thiocyanate may be most cost effective vs results.
     
  4. Ian Grant

    Ian Grant Subscriber

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    There should be no differance in results.

    I use a different formula

    Ilford IT-4

    Ammonium Thiocyanate 20gms
    Gold Chloride 1gm
    Water to make 1 litre

    Tone in IT-1 (sulphide toner) or IT-2 (Hypo-alum) first then immerse for about 10 mins then refix in plain 10% Hypo

    I actually usually tone in a Thiourea tomer first and get great salmon pink tones - flesh tones for hand toning & colouring images.

    Ian
     
  5. ann

    ann Subscriber

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    thanks Ian, am using this for extended toning, not for color shifts or with use with other sulphides toners.
     
  6. Ian Grant

    Ian Grant Subscriber

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    Anne

    What is extended toning, do you mean afchival permanence ?
     
  7. Nick Zentena

    Nick Zentena Member

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    My limited understanding is potassium type chemicals are used when you need to make up stronger solutions. It's possible to get more of the potassium anything into solution then the sodium versions. Other then that I think it's mostly a factor of what you can find in the chemical box.
     
  8. Ole

    Ole Moderator Staff Member

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    The only case (in silver gelatin processing) where it makes a big difference which cation you use is in fixers where ammonium is faster than sodium, and potassium hardly works at all. In toners, you can safely use whatever you can find.
     
  9. ann

    ann Subscriber

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    thanks again to all. Since i have ammonium and sodium types of hand and the potassium version is twice as much money it becomes a no brainer.

    Last night i read the description of each in my old Morgan and Morgan index and under uses, each description was exactly the same.

    Ian.
    extending toning comes from Les . I am toning 1 hour in selenium for 1 hour and then in gold for 90 minutes. He uses various times (check his book) I have just chosen the above, liked the results and use it for some images, not all.