Metalic look of old photos

Discussion in 'B&W: Film, Paper, Chemistry' started by mattk, Feb 6, 2008.

  1. mattk

    mattk Subscriber

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    Reviewing some old photos of family, I noticed that when viewed from an extreme angle, the black of the prints looks iridescent black. Is this just an effect of the silver--it almost looks as though it is solid metal. I only ask because I never notice this on any of my prints FB or RC. The photos were made in the early 1910-1930's. I'm wondering if this is the result of a certain printing process.

    Taking a study break,

    Matt
     
  2. pgomena

    pgomena Member

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    Not the result of a printing process, but rather the degradation of the image due to exposure to atmospheric pollutants, etc. This is pretty normal in old photos. They are "tarnishing" or "mirroring" or "silvering out." Not much to be done about it unless you make copies or scan them. Store them in archival paper envelopes or folders in an acid-free storage box.

    Peter Gomena
     
  3. BobNewYork

    BobNewYork Member

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    Mt experience has been that once the "silvering out" gets to a stage where you notice it, the rate of deterioration seems to accelerate. (I hasten to add that this is not a scientific evaluation) If you want to retain the prints for posterity I'd advise making copy negatives ASAP before they turn completely black. Make no mistake, this is a terminal condition.

    From another perspective, however, that iridescence looks really cool!:tongue:

    Bob
     
  4. Sparky

    Sparky Member

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    I don't see why you couldn't place such a photograph in a bath and deal with it with one of the following processes;

    1. sodium edta chelation (probably wouldn't work - but worth a try maybe), or
    2. anodize the thing while sitting in an appropriate solution - you'd probably lose a TINY bit of density. But it'd be worth a try. who knows...?
     
  5. Uhner

    Uhner Member

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    I might be channelling future generations now, and I do believe that my recommendation is redundant – but please make copies of the prints before you even consider to use any form of chemical on them.
     
  6. Konical

    Konical Subscriber

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    Good Morning,

    One of the problems with possible chemical treatment of deteriorating prints is that many old prints are commercial studio work, typically portraits, and they are often mounted. Making a good copy negative is highly advisable; that's one reason I have several hundred sheets of Kodak Commercial film in the freezer.

    Konical
     
  7. pgomena

    pgomena Member

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    If you do copy them, you probably will have to use double polarization (lights and camera all polarized), and that may not remove all the glare from the tarnish. **warning: digital statements** I've scanned tarnished images using only the red channel to eliminate the bluish glare as much as possible, fixed them further in Photoshop, and then colorized them to a nice antique-y brown color. It works really well.

    Yes, it is a "terminal condition" and you should make copies. The rate of deterioration varies widely depending on original materials and quality of original processing and subsequent display and storage. Black-and-white copy negatives are a very good, stable storage medium. Copy prints are good for display. Store the originals away in acid-free paper and archive-quality boxes in a cool, dry, dark place.

    Peter Gomena
     
  8. panastasia

    panastasia Member

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    Yes, you are correct, polarized copy lights will eliminate the reflections. I restore old photos and have no problem with these.

    The "silvering" is the result of compression on the photo surface caused by other photos or things stacked on top of the print. This is one hypothesis I've been told. I'm sorry I can't validate this with any reference, though.
     
  9. Ole

    Ole Moderator Staff Member

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    I don't have much faith in that hypothesis. I've seen it happen to a modern RC print which was framed as soon as it was dry, but in a cheap supermarket frame. Over only a few months the dark areas took on a glossy blueish sheen, and within a year the midtones were blotched. That frame was definitely not "archival" - so I kept it hanging on the wall to demonstrate (to customers) the value of proper framing materials!
     
  10. john_s

    john_s Member

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    It's a chemical process. This means that placing the photo in an area with restricted air flow and against other materials that contain certain active chemicals can lead to silvering. So having a print in a pile of ordinary paper or cardboard can lead to the problem, just as trapping a print in an unsuitable frame can.
     
  11. BobNewYork

    BobNewYork Member

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    I seem to recall hearing that the silvering was due to incomplete fixing, which over time enabled the remaining halide to convert to metallic silver which, in turn, migrates to the surface of the print.

    I'm not a chemist or physicist but intuitively that kinda makes sense to me.

    Bob