D-76 stock solution storage life

Discussion in 'B&W: Film, Paper, Chemistry' started by GRHazelton, Jun 7, 2012.

  1. GRHazelton

    GRHazelton Subscriber

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    I have just inadvertently tested the storage life of D-76 stock solution. I normally make up 1 gallon of undiluted solution using distilled water, put it up in 1 liter heavy plastic bottles with as much air as possible squeezed off. These I then dilute 1 to 1 as needed.

    Yesterday it seemed time to mix up a fresh gallon. Searching around in my storage cupboard I found to my chagrin a liter bottle, unused, labelled 3/24/2010. It had been kept a room temperature, and in the dark.

    Since I had a cassette of film used just for fooling around I processed it, the results look good. Kodak, with commendable caution, cites a 6 month storage life. While I can't recommend over two years, at least it does seem to work properly.
     
  2. cliveh

    cliveh Subscriber

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    I quite often use D76 which is over a year old and kept on a window ledge. As long as you don't let it oxidise it will probably keep for 2 years or more.
     
  3. pstake

    pstake Member

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    Good to know!
     
  4. Rich Ullsmith

    Rich Ullsmith Subscriber

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    Two years easy, as long as you don't mix the powder and water in a blender.
     
  5. michael_r

    michael_r Subscriber

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    ...however it is well known the pH of D76 rises over time with storage, making it more active. This would tend to raise contrast.
     
  6. brian steinberger

    brian steinberger Member

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    I was always curious, over how much time are we talking? I mix up 5L of ID-11 and use it all within 3 months.
     
  7. michael_r

    michael_r Subscriber

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    Brian, my understanding is that if the "original" formula is used the pH can increase over the first few months - ie it is not limited to long term storage. However I probably should have been clearer in my post that if you buy packaged D76 or ID11 this may not necessarily be the case. Who knows what tinkering has been done by Kodak over 80 years. And Ilford's two-part packaging may indicate it is slightly different in composition to packaged D76 as well.

    Some people say the pH still rises, some say the pH rises but the effect of higher activity is largely offset by the loss of Hydroquinone in that reaction, and I've even seen it said the current versions of these developers do not undergo a significant pH change with storage.

    So apologies in retrospect for being too simplistic in the post. It would be interesting to test this with both D76 and ID11, but I wonder how reliable the results would be unless done by the manufacturers. Simple experimental error, different storage conditions and/or normal processing variations could make it difficult to come to conclusions outside a laboratory setting unless the results repeatedly showed big differences over time. If not, I guess we don't have anything too significant to worry about.