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  1. #1

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    Shelf life of chemicals powder

    I found today a very well capped glass brown bottle full of sodium sulfite powder and others assorted photo chemicals in an ancient photo studio. I presume it date from the early 80. Before to use it I ask your experience with old chemicals. Have you experiences in shelf life of chemicals in dry form?
    How long pyrogallol or pyrocatechin will last in the right container well capped and in dark place?
    Perhaps tommorow I will have some others well conserved, twenty years old, chemicals....

  2. #2

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    Most photographic chemicals will remain stable for a very long time if they are kept cool, dry and dark. There are exceptions - glycin is one example. I have sodium sulfite from the 1940's that is still ok, and some pyrogallol and hydroquinone from the same era that is ok as well.

    I have previously written about the Phenidone I bought in the early 1970's (stored in amber glass containers) that is still fully active. I mixed some concentrated developer with it yesterday.

    I also have potassium bromide that has turned into a facsimile of a concrete block - stored it in the wrong environment.
    Tom Hoskinson
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    Everything is analog - even digital :D

  3. #3
    juan's Avatar
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    Tom, would refrigerating glycin help it keep in a hot climate?
    juan

  4. #4

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    Quote Originally Posted by juan
    Tom, would refrigerating glycin help it keep in a hot climate?
    juan
    Good question, Juan.

    I don't know, but I suspect it keeping it cold would help.

    I have a small amount (about 5gm) in a sealed amber glass container. I'll divide the glycin in half and put one half in the lab refrigerator (both in amber glass containers). I'll keep the other half in the lab cabinet (dark, 21 degrees C).
    Tom Hoskinson
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    Everything is analog - even digital :D

  5. #5

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    I founded others chemicals yesterday in this old darkroom. Some of them are still in the producer plastic can. Most of them are sodiium derivate (sulfite, carbonate, citrate...) there is some silver nitrate and ferric oxalate and metol.
    They seems well conserved, today I will mix some simple formulas to test these old powders, hope some of them will work. I'm quite happy because the owner of the flat is going to throw away everything. He is not involved in photography and the darkroom is gone more than twenty years ago.
    Thanks to Tom for share his experiences.



 

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