Homemade Sistan equivalent

Discussion in 'B&W: Film, Paper, Chemistry' started by Claire Senft, Aug 19, 2005.

  1. Claire Senft

    Claire Senft Member

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    I, cheap guy that I be, am looking for a formula and other information regarding home preparation of a Sistan equivalent. I already realize that the principal ingredient is potassium thiocyanate. Here are my questions.

    Formula for mixing.
    concentrate usage.
    amount of time in the bath
    the amount of coverage for a given amount of bath will process.

    It should be easy to discern what I know about this chemistry...virtually nothing.

    All I am trying to do is to produce prints with an enhanced LE. The prints will be subjected to a 2 baths of hardening fixer, hypo eliminator..not hypo clearing agent, 1:40 selenium toning. I realize that there is a school of thought that says that some residual hypo is good for the print in terms of resistance to air pollution. What is not stated is what amount of hypo should be left in the print and a technique to measure it that one may apply with confidence at home. I am neither taking issue with the accuracy of these statements nor am I trying to pick a quarrel who process in a different manner..different strokes for different folks. I believe a hardened print may have some benefits in terms of abrasion resistence or the application of pressure to the face of the print. I realize that hardening will reduce washing efficiency..hence the use of hypo eliminator and make spotting more difficult...nothing is quite as satisfactory as a print that does not require spotting. I also realize that I could enhance print LE though the use of heavy sulphide toning whose print colors I ordinarily dislike for my own work...I like slightly cool to neutral print colors. So, it seems to me that a Sistan like solution may be helpful.
     
  2. George Papantoniou

    George Papantoniou Member

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    I apologise for being slightly off-topic, but is hardening something that works on prints too ? I had the impression (think I read it somewhere) that hardeners only work on film and on FB prints they are useless... They are substances that harden the gelatin layer of the film, no ? Would hardening the gelatin layer of FB paper be useful ? Is the gelatin layer of FB paper made in the same way as the film's is? If it works (hardening the gelatin), wouldn't it make it harder to wash the hypo off the emulsion ?

    If you want to apply the "small amount of residual hypo" method of print conservation, then you can use the "hypo spray", a device that allows you to re-introduce a bit of hypo on a thoroughly washed and dried print. You just put your print on a flat surface, then spray it using the specially-made spray can from a distance of 10 inches. The amount of hypo introduced is scientifically proven to preserve your print from future acid air pollution. My company will be happy to supply you with any number of "hypo spray" cans you need at a special introductory discount price.

    Moderators, feel free to delete my post. I know, I am a pathetic compulsive liar...
     
  3. Claire Senft

    Claire Senft Member

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    I know that replying in a serious manner to a known liar who is noted for being a good for nothing son of a bitch is not effort that is well directed.

    Yes, hardening works on prints.
     
  4. Gerald Koch

    Gerald Koch Member

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    The MSDS for Sistan lists:

    Potassium thiocyanate CAS 333-20-0 15 - 20%
    Triton 2000 CAS 9002-93-1 5 - 10%

    Triton 2000 is also called Triton X-100 and is available from http://www.chemistrystore.com

    Should be easy to mix this up. I would use 175 g of potassium thiocyanate (the average) and 50 ml of the wetting agent Triton X-100. Dilute this 1:40 for the bath.

    I would add the X-100 first as it is very viscous and hard to dissolve and then add the thiocyanate which is very easy to dissolve.
     
  5. psvensson

    psvensson Member

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    Thanks, Gerald, I knew I'd seen that somewhere but couldn't find it. There was a discussion about Fuji's Sistan equivalent, Ag-Guard, which some say is superior, on the pure-silver list, with an approximate formula:

    http://www.freelists.org/archives/pure-silver/06-2005/msg00079.html

    But Claire, if archival stability is your goal, I think a sulfide toner would be best. We just don't know enough about the effectiveness of Sistan. You say you don't like the image tone, but there are several neutral papers that don't really change tone in KBT. MGIV would be one.
     
  6. Ole

    Ole Moderator Staff Member Moderator

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    Yes, Kodak Rapid Selenium Toner contains "some" fixer. Quite a lot of it in fact, I can't remember the percentage but there is enough ammonium thiosulfate in it to bleach a salt print to nothing before the toner starts working. And that's at 1:40.

    I believe hypo eliminator before KRST is at best a waste of time.
     
  7. Gerald Koch

    Gerald Koch Member

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    Ag-Guard *might* be better but the principle ingredient is most likely hard to obtain. Both ingredients in the Sistan product are readily available.
     
  8. Photo Engineer

    Photo Engineer Subscriber

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    If you allow a small amount of hypo to remain in a print, it decomposes slowly releasing sulfur compounds which coat the silver and protect it from oxidation much like sulfide toning.

    Sistan, and other stabilizers like it contain similar sulfur releasing compounds in low concentration which work to stabilize the silver in a siimilar manner and prevent image degradation.

    All of them are pretty much the same. And, you can use Sodium Thiocyanate instead of Potassium Thiocyanate by adjusting the quantity for the change in molecular weight of Sodium vs Potassium.

    There is an article publised by Ctein on this subject. I recommend it to you all.

    PE
     
  9. Claire Senft

    Claire Senft Member

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    Thank You one and all.
     
  10. Gerald Koch

    Gerald Koch Member

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    There are two problems in using any toner to achieve image permanance. The first is any change in image tone. That a particular paper presents the least amount of change is only a partical solution since one is restricted to that paper. The second and most important is that there is little agreement concerning the amount of toning necessary for permance. Some say that the entire image must be toned while others say that partial toning is sufficient.

    Concerning the exact amount of residual hypo required for permanance, there appears to be some leeway. Prints treated with a washing aid and then washed for the "classical" times seem to be ok. The protective value of small amounts of hypo was only discovered when prints treated with Kodak's HE-1 formula, popular during the middle of the last century, began to show serious degradation. HE-1 converts any residual hypo in the print to sodium sulfate, which is photochemically inert. The exact mechanism for the protection is poorly understood but appears to depend on the decomposition of the hypo to various sulfur compounds and elemental sulfur. This brings up an idea that the best toner for archival permanance might be the hypo-alum toner. This toner is based on the decomposition of hypo in a controlled way and probably contains many of the sulfur compounds thought to be advantageous in correctly washed prints.
     
  11. Claire Senft

    Claire Senft Member

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    I can see that I confused the issue myself by mentioning hypo eliminator prior to mentioning selenium toner in the list of what I do. I have always used the hypo eliminator at the end of the process just prior to print washing.
     
  12. Ryuji

    Ryuji Member

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    The mechanism of image protection by impregnation of the gelatin layer with thiocyanate is completely different from the mechanism of image protection by residual thiosulfate. The image protection by thiocyanate can be removed by water rinse after Sistan treatment. However, image protection by thiosulfate persists even after brief water rinse. I'm not going to get into details but the chemistry of these image protection mechanisms is discussed in a few papers written by Fuji people in 1980s. Unfortunately, all in-depth discussions (including one review paper) are written in Japanese language.

    I STRONGLY recommend anyone who is serious about image permanence to stick with one of the well tested treatments and refrain from jumping on untested homebrews.


     
  13. Ryuji

    Ryuji Member

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    Sistan is cheap, especially if you consider how much time, work and other archival storage/mounting/framing supplies cost. Stick with Sistan. However, a better option is Fuji Ag Guard, which uses an organic thiol compound that is even more effective than thiocyanate. The Fuji product is great because some image protection power remains even if the treated print is rinsed in plain water. The Sistan treatment is unreliable if there is humidity cycle in the paper storage. Also, Sistan treatment is even harmful if the amount of thiocyanate in the emulsion/paper is too high.

    A better approach is to use paper-developer combination that would give you cold black tone when toned in polysulfide toner. I've posted here and also on photo.net about how to think about developer's influence on the hue of polysulfide-toned prints. I've made quite a few samples of neutral black print (after polysulfide toning) which showed excellent resistance to oxidative attacks in peroxide fuming testing.