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Thread: Color print film C-41 kit (mixing question)

  1. #1

    Join Date
    Dec 2019
    Posts
    96

    Color print film C-41 kit (mixing question)

    Hi.

    I'm about to try out C-41 developing for the first time. For me the amount of film (rolls and sheets) will be small so chemistry longevity is an important thing to me.

    I've read in at least one or two blogs that some people mix up a half batch and use 500ml at a time instead of the full 1000ml (1 quart kit size).

    What I'm not clear on is, do you mix the entire batch of chemistry and then divide it into two separate working sets (one for now and one for much later) OR do you cut the kit solution in half and only "mix" one half and retain the other half un-mixed in the original bottles for later use?

    Does anyone have experience with this stuff? Suggestions? My primary aim here is to stretch the lifespan of the chemistry not to get more cycles on it.

    Thanks!!!

    Adam

  2. #2

    Join Date
    Jun 2014
    Posts
    1,721

    Re: Color print film C-41 kit (mixing question)

    This has been discussed many times, particularly on Photrio. I would suggest doing a search on Google to find some insights.

    In short, both of the options you mention are used by some, but the main source of concern is that one part of the developer (the part containing the actual developing substance) has a very limited lifetime as soon as it's opened. It needs to be used up within a few weeks after opening it. It turns out that if you mix it all at once and then store the ready-made developer in entirely full, tightly capped glass bottles, the solution generally has a lifetime of several months or even up to a year without noticeable quality loss.

    The alternative is to only mix part of the kit, but then the developer concentrate containing the development agent needs to be stored in absence of any oxygen. For this purpose, it can either be decanted into a glass bottle of the correct size so that no air sits on top, and/or a purge gas may be used (e.g. Tetenal Protectan or lighter gas/butane).

    Personally I prefer to mix it all at once, store it in smaller bottles and then try to use it up within a reasonable amount of time.

    Please note that the concerns outlined above do not apply to the bleach or fixer (3-bath kit), and to a lesser extent to blix (if it's a 2-bath kit). The bleach and fix or blix concentrates can generally be stored in opened, half-filled bottles for an extended period of time; virtually indefinitely for the bleach and up to a few years for the fix.

  3. #3

    Join Date
    Dec 2019
    Posts
    96

    Re: Color print film C-41 kit (mixing question)

    Ok. Thanks. I'm reading that forum now, but not to stoke your egos too much, I kinda like getting the final word from this crew. Honestly I think the feedback is better. More grounded.

    So if anyone else has an opinion on this matter please feel free to educate me.

  4. #4

    Join Date
    May 2018
    Posts
    116

    Re: Color print film C-41 kit (mixing question)

    I actually buy the 500 ml kits.

  5. #5
    Studio Madbird
    Join Date
    Nov 2015
    Location
    Portland OR
    Posts
    30

    Re: Color print film C-41 kit (mixing question)

    Hi- The last 1000ml kit I had I kept the mixed chems (2-bath) in the fridge between uses and it was still fine after 9 months, but I dumped it after that, not wanting to push my luck. I’ll see how long this new kit lasts, confidence is high!

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