Long-term storage of unused emulsion

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by Nodda Duma, Jan 31, 2017.

  1. Nodda Duma

    Nodda Duma Subscriber

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    Due to my work schedule, I had an impromptu opportunity to test photographic emulsion which I had mixed at the beginning of July (almost 7 months ago) and stored but never coated plates with. This might be of interest to those of us who cannot use up a full batch of emulsion all at once.

    Here is the background info:

    Recipe: http://unblinkingeye.com/Articles/Emulsion/emulsion.html
    No preservatives added, recipe is as described in the article. I probably didn't after-ripen as much as I could have. Emulsion speed tests at ISO 0.25 - 0.5 (same as what fresh emulsion tested at).

    The emulsion is stored in a refrigerator, at ~36F. I store my emulsion in sanitized light-tight cheese crocks, like what is seen in this link: https://img1.etsystatic.com/000/0/6307290/il_fullxfull.329847525.jpg

    I separate each batch into 4 cheese crocks, so that when coat plates I can minimize the number of times I remelt emulsion.

    I coated a batch of plates when fresh (beginning of July). Coated a second batch of plates in September (after 2 1/2 months of storage). Just coated 3rd batch during the last week of January (just under 7 months of storage). Note that I did not remelt emulsion for the second run -- it was out of a container that hadn't been used for the 1st batch. I did remelt the remainder of that container for the 3rd batch, so the emulsion had seen no more than 2 remelting cycles.

    Inspected surface of set emulsion, did not notice any mold growth or decay.

    Melted and hand-coated at 104F onto prepared 5x7 and 5x4 plates. No particular issues with coating, took about 1-2 hours to dry.


    Tested for ISO speed, developed in HC-110 Dil B and Fixed in Kodak Hardening Fixer. Emulsion did not exhibit any unusual behavior during development. It works like new!

    Sensitivity and gelatin properties didn't seem to be affected by the length of storage.


    I still have some left of that batch. I will probably recoat in a couple months and let you know how it goes.
     
  2. M Carter

    M Carter Member

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    I haven't made emulsion, but I have a liter-size of Foma liquid in my fridge. It was over a year between purchase and my first use and it was perfect. Been another year now and I need to test it. Seems like the fridge is the way to go with this stuff?
     
  3. Photo Engineer

    Photo Engineer Subscriber

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    Always use a fridge, never freeze or leave at room temp. Never heat the entire batch to remove just a little, scoop out what you want with a scoop leaving the rest as a solid.

    To me, it's funny to say that. I used to scoop it out of huge containers by the double handful! :D :D

    PE
     
  4. fdonadio

    fdonadio Subscriber

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    Ahh, the good old times! :smile:
     
  5. OP
    Nodda Duma

    Nodda Duma Subscriber

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    Another data point: Coated ~80 plates over the few nights, and no issues with how they coated down. In both cases I heated the emulsion to 135F and held for 15 minutes, then coated as the emulsion cooled to 104F.

    That puts the emulsion at 9 months old, continuously refrigerated except when brought out for coating.

    Will post results when I've taken a test exposure and developed.