How to avoid oxidation of the c41 developer?

Discussion in 'Color: Film, Paper, and Chemistry' started by narigas2006, Mar 26, 2008.

  1. narigas2006

    narigas2006 Member

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    Sorry for my ignorance but the problem of oxidation is only the pH (i mean, if I correct the pH the developer would keep functional) or is there any major chemical changes that makes the developer unusable?

    I am asking because I wanna build a developing tank with a very large surface area and I wanna avoid oxidation. Many thanks!
     
  2. Mike Wilde

    Mike Wilde Member

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    my C41 habits

    I scratch mix c41. I start with pre-boiled and cooled reverse osmosis water. I fill the glass storage bottle with nitrogen, and store the bottle in the refrigerator when I am not using it.

    I try to accumulate films before processing, because once processing starts and the developer is partially used it will deteriorate faster in storage.

    I process in tanks. If I am using a stainless steel tank, I will fill it completely, in order to minimize the amount of air that it will contact during agitation. If I am using plastic reels in my paterson tank, I only spin it to agitate; there is too much air in the tank to do inversion agitation. I suppose that I could fill the tank with a blanket of nitrogen before snapping the top on.

    If you are working in open tanks, then you may want to consider floating saran wrap on the surface if you want to leave the solution in the tank for a few hours between uses.
     
  3. Discpad

    Discpad Member

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    When you mix your color developer replenisher, pour it off into 1 liter soda bottles (leaving about 1-1/2 inches for expansion) and freeze what you don't plan on using that day. You can also freeze extra E-6 1st & color dev replenishers...
     
  4. narigas2006

    narigas2006 Member

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    I remember there was an old post saying that freezing would screw the solutions, did u try it? is it ok after? cheers
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    Freezing can cause some developer solutions to form an oily mixture of organics on the surface. These rapidly oxidize and are difficult to redissolve. If this happens, then freezing is bad. If it does not, freezing is not bad.

    C41 does not suffer from a pH instability problem. As long as it is at pH 10.1 at 20C, it has a good pH, but the real problem is oxidation of the developing agent. If the developer solution turns darker than strong tea, it is bad.

    PE