Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,501   Posts: 1,543,351   Online: 865
      
Page 2 of 2 FirstFirst 12
Results 11 to 15 of 15
  1. #11
    Mark Fisher's Avatar
    Join Date
    Dec 2003
    Location
    Chicago
    Shooter
    Medium Format
    Posts
    1,627
    Images
    151
    Is there a reason that selenium toner needs to have fixer in it? Would it be possible to make selenium toner in some other sort of solution that would not bleach? I'd love to have it as an alternative to gold or palladium toners for lower cost and another choice on tone.

  2. #12

    Join Date
    Jan 2006
    Location
    Los Angeles
    Shooter
    Multi Format
    Posts
    110
    Quote Originally Posted by JG Motamedi
    Hey Kevin, funny meeting you here....

    David, it is hard for me to tell on screen, how does the tonality differ from a regular gold chloride print? I note that the Chicago Albumen Works (POP manufacturers) has a selenium toning formula on their website, but I have never tried it.

    As an aside, Blake at http://mostlymetals.com has good prices for Gold Chloride, about $22 per gram with a minimum order of 5 gram. He is also an good guy who makes Uranotypes...

    jason
    Jason,
    Thanks for the lead on less-expensive gold chloride. It's been a while since I toned my prints in gold. Like everybody else, I have been deterred by the cost. Plus the fact that the toner itself is very short-lived, and demands that the printing workstream be built around optimizing the use of the gold toner.

  3. #13

    Join Date
    Jan 2006
    Location
    Los Angeles
    Shooter
    Multi Format
    Posts
    110
    Quote Originally Posted by Mark Fisher
    Is there a reason that selenium toner needs to have fixer in it? Would it be possible to make selenium toner in some other sort of solution that would not bleach? I'd love to have it as an alternative to gold or palladium toners for lower cost and another choice on tone.
    Hi Mark,

    First of all, let me say that my understanding of photochemistry is nowhere near that of some of our members, so I can only guess at the reason. I suspect that the inclusion of thiosulfate in off-the-shelf KRST is a form of insurance against getting inconsistent toning results and staining in prints.

    I think that using KRST in toning prints (silver gelatin primarily) involves two simultaneous processes similar to that of monobaths in film developing. In monobaths, the developer acts on the exposed silver, while the fixer simultaneously dissolves the unexposed silver. For monobaths to work properly, a balance must be struck between the speed of development vs. the speed of dissolution of the unexposed silver.

    In a KRST solution, the selenium probably works on areas where silver compounds are present the most (shadow densities), and proportionately less on the midtones and highlights. Meanwhile the thiosulfate simultaneously works to remove any "free-floating" silver remaining in the print. If you recall, there is the standing rule that prior to any form of toning, the print should be thoroughly fixed, as well as thoroughly washed. I presume this is to remove all traces of non-image silver, and to remove any compounds formed by the fixing process. The presence of thiosulfate in the KRST solution is probably designed to ensure that the selenium gets to work cleanly.

    As an aside: A long time ago while I was working for a media house in Asia, we were able to order selenium powder from a chemical supplier. We would mix a selenium solution and apply it locally to portions of B&W prints with watercolor brushes. The result was the most 3-D B&W prints you ever saw! Prints that were impossible to create by conventional darkroom methods. All this before the advent of unsharp masking or Photoshop.

    But since selenium has been classified as toxic (as is many other photography-related chemical compounds), I doubt if it is still possible for individuals to purchase selenium powder to use directly as a toner.

  4. #14

    Join Date
    Sep 2004
    Shooter
    Multi Format
    Posts
    343
    David,
    Your answer seems clear and I think the only part of my post you deleted was what I had quoted from your initial posting. Ya gotta watch yourself carefully when you're wielding those "moderator superpowers", kinda like the Charlie Chaplin carrying a ladder. I was just curious because everything I have read suggests that toning first is optimum.

    I think the reason you are getting excessive bleach-back is simply the KRST is quite bit more concentrated that necessary. As an example, 1+200 works well on Vandyke (toning times in the 10 minute range and a measureable increase in dmax vs untoned). I know that albumen and VDB sensitizer are not the same but the starting point of the image (silver nitrate) and the root problem (bleach back due to thiosulfite/thiocyante in the toner) are similar. I have used KRST on both Abumen works POP and old studio proof and the problem is similar. I had to give a presentation/demonstration recently, part of which was a toning sequence for VDB. I sifted through my small collection of ancient photgraphic how-to books on the premise that research was the better part of valor when faced with public speaking. What I gleaned from my survey of available literature was: toning first was traditionally done to avoid or mitigate bleach back, and VDB prints do not seem to traditonally have been toned. Anyway, toning first seemed the logical nod to received wisdom and it seems to work well if you get the dilution right. As to economy vs gold toning 5ml/litre really milks a long life out of a bottle of KRST.
    Celac.


    Quote Originally Posted by David A. Goldfarb
    I'm not really sure. I did take a couple of slips of exposed albumen paper and tried one one way and one the other, and the one that I did selenium first then fixer lost more density in the toner than the one that I did fixer first, so I suspect that's the reason.

    Generally, one exposes albumen paper so that the untoned print is about 1.5 to 2 stops "too dark," because it lightens up in the toner, then lightens more in the fixer, though it then has some dry down, so it gets a little of the density back.

    I suppose another issue might be that gold-alkali toners are alkaline, and fixing first might more quickly exhaust or contaminate the gold toner, where that wouldn't necessarily be a problem with selenium (since we do it all the time with regular silver gelatin papers).

  5. #15

    Join Date
    Mar 2006
    Shooter
    Large Format
    Posts
    133

    Sulfide Albumen toning

    It is important that you Fix and wash the print before toning with Sulfide toner.

Page 2 of 2 FirstFirst 12


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin