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Thread: Toning and Permanence

  1. #51

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    Toning and Permanence

    Ed Buffaloe's cite, The Unblinking Eye, has a concise and well written article on archival processing. In that article, I came across the following:

    "Doug Nishimura indicates (in a letter to Jennifer Scott) that complete protection with Kodak Selenium Toner requires a dilution of not more than 1:9, and a toning period of 3 to 5 minutes at 68Ί. Some fine art photographers find this depth of toning not to their taste."

    What is interesting to me personally about this is that the paper I use, Ilford MGIV Fiber, requires almost exactly this dilution and toning period to get a discernible increase in DMax. While there is, to my eye, almost no change in image color, is it possible that, after all, I have been toning sufficiently for archival permanence? To put this another way, for an area of the picture to be protected by the toning, must there have been a visible change in density and/or image color? Do any of this forum's scientist contributors have an opinion on this?

    I also found, in the same article, some information on Agfa Sistan:

    "Other Treatments: Agfa makes a product called Sistan, and Fuji makes a similar product called AG Guard, which is used to treat prints after washing. Thomas Wollstein has corresponded with Agfa regarding Sistan, and tells us that Sistan contains potassium thiocyanate and a wetting agent--it works by converting oxidized silver ions in the emulsion to a stable, insoluble salt. Robert Chapman states that Sistan “...precipitates any silver ion formed by oxidation in the form of silver thiocyanate (AgSCN). Silver Thiocyanate is colorless and virtually light-insensitive.” But Sistan only works as long as the thiocyanate stays in the emulsion, so Agfa recommends that Sistan be used as a final treatment, after washing and before drying--if it is washed out, archival benefits are probably lost.

    According to Doug Nishimura, “before any silver deterioration can occur, silver must be oxidized into silver ion. Even air and moisture can act as a strong enough oxidizing combination to cause damage.” He notes that “...there is always a small amount of ionic silver in equilibrium with silver metal in a photographic image.” But, whether the ionic silver already exists in the emulsion or is caused by pollutants, thiocyanate combines with it, thereby stabilizing it as an inert salt which will not cause image degradation. Sistan is said to be fully compatible with toning treatments. I should note that Dupont 6-T Gold Toner contains potassium thiocyanate, and Kodak GP-1 contains sodium thiocyanate, but I do not know if either is in sufficient quantity to be as effective as Sistan is alleged to be--also, prolonged washing would negate any benefit derived therefrom. Robert Chapman states that, though he has inquired several times, Agfa has not provided him with substantive documentation to prove the effectiveness of Sistan. He allows, however, that “..it makes sense on theoretical grounds.” Other sources on the world-wide-web hint that Sistan may not be effective over the long term, but there is no hard data to back this up either."

    Obviously, then, for those who want the effectiveness of the treatment demonstrated before adoptiong it Sistan would not fill the bill.

  2. #52

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    Toning and Permanence

    I am surprised so few people here and elsewhere have asked what the contaminant is. Apparently there is a substance which can be present in such small amounts that it doesn't show up in Kodak's production line assays, yet which affords silver images the protection always attributed to selenium and gold. The real question should be why is nobody bottling it and selling it.

    Optical brighteners are not necessarily evil. Some may in fact help preserve the image as by definition they absorb UV light. That said, the one I know about - TiO2 - catalyses a number of organic decompositions, and photocatalyses even more. A standard treatment to remove organic contaminants is to pass water over a Ti02 support illuminated with UV.

    Finally, a comment on archives: like many state funded institutions it is much easier to get money for sexy new equipment than for upgrading existing stock or for day to day operations and salaries. The library here, and a couple of county archives I know, have received money for swanky digibacks from private foundations that they would never have been able to raise for more mundane but arguably more useful purposes such as adding climate control to all the storage areas. It's the 'machine that goes ping' syndrome.

  3. #53
    Abuser of God's Sunlight
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    Toning and Permanence

    Struan, is Ti02 an optical brightener? and if so, is it the one that's used in modern papers? I only knew of it as a pigment.

  4. #54

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    Toning and Permanence

    It is used as a brightener in many if not all RC silver gelatin papers, and it would not surprise me to find it in inkjet papers too - although I have no confirmation of that.

    Again: it is not evil incarnate, but with the benefit of hindsight, it came as no surprise to me to see it fingered for at least part of the RC bronzing problem.

  5. #55

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    Toning and Permanence

    PS: it is used in RC papers because of its high specular reflectivity. It doesn't have the strength of fluorescence of phosphorescence that optical brighteners in, say, washing powder have (which is why it is used in blackberry-powered solar cells, but that's another story).

  6. #56
    Abuser of God's Sunlight
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    Toning and Permanence

    Interesting. I remember reading that Ti02 wasn't the most stable pigment in oil paints .. that it yellowed over time. which was suprising, since titanium is so nearly innert. aparently zinc oxide is more stable in paint.

    I've been working on varnishing my inkjet prints and was wondering why the varnish seemed to reduce the surface brightness of the paper (yellowing it slightly). the varnish is supposed to be acrylic based and crystal clear. then this thread made me realize--it has UV blockers, so the optical brighteners aren't getting their magic juice.

  7. #57

    Join Date
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    Toning and Permanence

    >>>>For example, I know you can buy walker evans prints, made from the original negatives, from the library of congress for dirt cheap. i'm sure these are rc, if they're not digital already. But the walker evans prints in the collection at MoMA are fiber based, and were printed by walker, or by someone he hired a long time ago. let me know if i'm missing something.<<<<<<<<

    okay--the art museum piece is the original, or as close to it--it's the real mccoy, the "artifact". the LOC, or any other archive for that matter, is a reproduction. Chances are it won't come off the original negative, but will come off a duplicate of the neg, or a copyneg of a print--or some combination of the two meaning, it could be many times removed. It might be a good reproduction of an original print, but it's not the same thing by any stretch of the imagination.

    Art museums do not generally print for their collection. They collect by purchasing, donation or loans....there's a fundamental difference here---a case of miscommunication between you and I. I'm talking about records, in that these are copies and duplicates of existing photographs or they are original photographs that were shot for the purpose of documenting an object or a building or even an event to support some broader idea.

    It's just completely different, but the original records are treated with the same care as the artifact--only they're duplicated in an effort to preserve them and as a way of disseminating the information to the patron base--which now in the age of the internet means that a state museum or a county historical society often serves a much wider audience than many of them ever imagined. It is both exciting in some ways, and unrealistic in others--but like Struan's comment about fundraising and basic priorities--I can't even begin to go there in talking about this, it's just too close to home...just no comment really. Times change--you gotta go with the flow, or find something else to do.

    I got a slip of paper about my retirement today. seems like I have about 15 some odd years to go before full retirement. Tell you what--in 2020, when I'm living off my pension, and not selling Grit door to door to supplement it--I'll get back to y'all about selenium toning when I'm tooling around in my own darkroom, assuming of course there's still some photo papers being made, and I'm not too senile or burned out to remember how to use the stuff.

  8. #58

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    Toning and Permanence

    "But I've not seen an OBA free gelatin silver paper in the past decade. Is there a commercially available gelatin silver paper that is actually free of optical brighteners? I doubt it."

    As best I can determine, Azo does not contain optical brighteners.

  9. #59
    Abuser of God's Sunlight
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    Toning and Permanence

    if fortezo contained them, it sure didn't look like it.

  10. #60

    Toning and Permanence

    I'll eat my words.

    As far as I can tell, doing some research on the web, recent Kodak fiberbase papers with a 'C' finish are OBA free. Don't know about Azo.

    Apparently the Cachet/Maco papers are OBA free.

    From what I've read, it's possible for a paper to look like it's oba free but still have OBA's in the paper base.

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