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Thread: Processing brand-new old glass plates

  1. #1

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    Jun 2006
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    Processing brand-new old glass plates

    Hello,

    I bought in a flea market 36 glass plates yet in sealed boxes.
    It is for stereo cameras 6 x 13 cm. It happens that I have a Voigtlander Stereflektoscope (http://www.lungov.com/wagner/c/026c.html) and would love to make some modern stereos with it.

    Plates are Agfa-Chromo-Isorapid. It is orthochromatic and anti-halo.
    The recommended developer is Rodinal 1:20 at 18ºC (not a word about time. I assume that being orto it is intended for development by inspection). It comes also with a remark: Pyro developer is not suitable. What else… not a word to identify year of production.

    Does anybody have a clue about Exposure Index and/or any recommendation/sources/on-line-literature on how to develop that?

    Regards

    Wagner

  2. #2
    Donald Qualls's Avatar
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    Re: Processing brand-new old glass plates

    In the day when those were made, everything was developed by inspection, so times weren't considered a necessity. You can still do this -- ortho film and plate emulsions can be handled under red safelight.

    The Rodinal they call out would be more like Calbe R-09 or Fomadon F-09 than modern formula Agfa or A&O Rodinal; if you have the modern formula, you'll want to use 1:25 in place of their recommended 1:20. I'd probably process them in HC-110 Dilution B, which has a strong anti-fog already in the formula and would slightly soften the grain, but I don't know how available that is in Brazil.

    I'd suggest trying the first one with an EI of 6, and adding around 0.5 g/L potassium bromide to your working solution (to combat age fog, since those plates are almost certainly pre-WWII, possibly 1920s or older); based on the results you can then adjust for following plates. "Isorapid" implies a high speed emulsion, which in the 1920s would have been equivalent to modern ISO 50 or so, but you can count on one stop or more of speed loss due to age.
    If a contact print at arm's length is too small to see, you need a bigger camera. :D

  3. #3

    Join Date
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    Brazil
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    Re: Processing brand-new old glass plates (THE RESULTS)

    Hello,

    I would like to share with you the results of my experiences with old glass plates.

    I made a test following Donald’s advice: EI 6 ASA, Rodinal 1+25 and 2.5 ml of 5% Potassium Bromide solution for 250ml of working solution. Being orthochromatic, I developed it with red safe light and it took 8 minutes at 20ºC. That was pretty close. It was workable as a negative but I felt a little over development because sharpness was not that good (for a Voigtlander Heliar) and high values deposits were saturating.

    Second try was Rodinal 1+50. That was very good. It took 10 minutes at 20ºC.

    Well, then I charged the film holder with 12 glass plates and made to São Paulo downtown in a sunny Sunday. Tripod was necessary because times fell about 1/8th of a second (6 ASA). I enclosed one of the pictures. Not in stereo, it is just a sample of image quality.

    The negatives show problems close to the edges. I cropped that part in the attached picture. There is like a frame 5 to 8 mm thick which is burnt. I guess it is the part that had more chances to interact with atmosphere over the years. By the way, opening the box I found a little piece of paper with expiring date: 1926 !! Mr. Qualls was right about that too: it is from the twenties.

    From time to time one can find in flea markets, trade shows of Ebay, sealed boxes of glass plates. I felt rewarding to rescue those from the “eternal darkness” and chemical corrosion by making a record of my time over recording material from long before my time. I am planning to put a complete report on my web site as a reference for whoever wants to try it too. I will post the link here for our LF enthusiasts.

    Many thanks to you Donald Qualls, your lead saved time and precious, unrecoverable vintage material.


    Regards


    Wagner

  4. #4
    Donald Qualls's Avatar
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    Re: Processing brand-new old glass plates (THE RESULTS)

    Quote Originally Posted by lungovw
    Many thanks to you Donald Qualls, your lead saved time and precious, unrecoverable vintage material.
    Glad it worked out well for you. Got some nice results there, it seems, and that's what it's all about, after all.

    You're probably correct, the fogged edges are likely due to either oxidation or just possibly background radiation, partially absorbed by the mass of glass (80 years is a long time even for a slow emulsion). Thanks for posting back, I'll look forward to the more complete report.
    If a contact print at arm's length is too small to see, you need a bigger camera. :D

  5. #5

    Join Date
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    Re: Processing brand-new old glass plates

    That image is brilliant. It actually makes me think of the 60's TV shows like Twilight Zone. Very vintage, and yet amazing tones and clarity. Good work!

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