Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,826   Posts: 1,582,012   Online: 866
      
Page 2 of 2 FirstFirst 12
Results 11 to 13 of 13
  1. #11
    Struan Gray's Avatar
    Join Date
    Nov 2004
    Location
    Lund, Sweden
    Shooter
    Multi Format
    Posts
    914
    The Image Permanence Institute developed a test for stability against plating out (or the 'red spot' problem in microfilms) which involved controlled exposure to hydrogen peroxide fumes. To make the test reproducible they had to go to some lengths to ensure a uniform H2O2 fume density, but the basic idea was to suspend the print/film over paper dampened with a peroxide solution.

    Plating out happens when an oxidant turns some of the image silver into silver ions. These migrate to the surface of the emulsion and are reduced back to silver again. If you want to play with standard photographic solutions a weak bleach solution would do the oxidation for you, which could be followed up by a residual silver test to re-form the silver, but you need to find a way to stop the silver migrating out of the emulsion altogether.

  2. #12

    Join Date
    May 2005
    Location
    Woonsocket, RI USA
    Shooter
    35mm
    Posts
    2,725
    FWIW, I've found that all my prints made on Foma VC RC paper and stuffed in cheap frames (the sort you can get for $5 at CVS or Walgreens) silver out within 1-2 years. I've used various fixers, but mostly TF-3. Prints made and framed in exactly the same way on Agfa VC RC paper haven't silvered out on me, even after ~5 years. (That's as long as I've been doing B&W printing, so I have no longer-term tests.) Prints made on the Foma paper and stored loose in envelopes or boxes haven't silvered out on me; just the framed prints have done so.

    All that said, I'm the only person I've seen who's reported this Foma-specific problem on APUG, so it's entirely possible the problem is an interaction of the Foma material with something specific to me -- chemicals in my wash water, peculiarities of (perhaps improper) processing on my part, trace chemicals in the air in my house, etc. If you're willing to wait 2 years for the silvered-out effect, though, and if you're willing to live with the probability that it will get worse and worse after that, you could try the Foma materials and see what happens....

  3. #13

    Join Date
    Feb 2005
    Shooter
    Large Format
    Posts
    852
    Quote Originally Posted by srs5694 View Post
    All that said, I'm the only person I've seen who's reported this Foma-specific problem on APUG
    It's not Foma-specific - as I recall, Ctein ran his tests on Agfa MCP, and the untreated print areas in his framed sample silvered out gloriously. The framing is evidently part of it, but beyond that we don't know why it doesn't happen consistently.

    So how to produce the effect consistently and more or less reproducibly, and to stabilize the resulting image once you've got it, is an interesting question.

    The MSDS for Rockland Halo-Chrome shows the part 1 ingredients as just ammonium and sodium hydroxide and the part 2 ingredient as cupric chloride.

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