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  1. #1
    Denis P.'s Avatar
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    Home C41 using commercial lab chems?

    Hi,

    After some searching through the forums, I still haven't found a clear answer to something that's bothering me: I'd like to try C41 at home, just for kicks - and perhaps do some color 4x5 negs later, when I get the hang of the process. I have a Jobo CPA2, and know how to use it - been using it strictly for B&W, though. Never done any color before!

    The problem is that I can't purchase small C41 kits locally (like Fuji X-Press). Shipping from abroad is way too expensive, so I asked my local photo lab for some of their chemicals. They said OK, but claim that the chems are suited for particular machine (theirs is Noritsu). I'd still like to try...

    From what I understand, I basically need a developer (or replenisher + starter), bleach and fix (or do I also need the stabilizer?).

    Anything I shuld know regarding using the commercial chemicals - i.e. those intended for commercial labs - at home in a Jobo processor?

    TIA,

    Denis

  2. #2
    tiberiustibz's Avatar
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    The key is to find mixing instructions. A developer is a developer is a developer. They're all the same as the home chemistry. If you can find out how to mix it you're good to go. You will need a stabilizer.

    It goes (@ 100 F 37.8 C) Prewet 1 min, Developer for 3'15", Bleach for 6'30", Fix 6'30", wash in running water at temperature for 3', stabilizer for 1'. I would recommend using distilled water in the stabilizer to eliminate drying marks as much as possible.

    Some Bleaches and Fixes (usually minilab type) will only need as little as 1 minute in the tank. Extra time can't hurt though so if you're not sure just use the longer time.

  3. #3

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    Some of the machines have chemical packs that plug into the machine. The machine does all the mixing etc. You need to avoid these.


    I disagree they are all the same. The fuji bleach I use is low replenishment. They make a different one that is rapid. Both Kodak and Fuji hunt used [might still] have all the documents on their websites. C-41 plus all the variations.

    The newer Kodak and Fuji chemicals don't need stablizer . Or so I thought.

  4. #4
    Dave Pritchard's Avatar
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    If you can identify the chemicals or brand that you have available to you from your mini-lab friend, we may be able to advise you on the mix you need for small scale c41 processing.

  5. #5
    Denis P.'s Avatar
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    Thanks for the info so far...

    So, it's not all the same, after all...

    I'll check out the chemistry they use, and will be able to provide more info later today. I'm quite positive it's Fuji chemistry, but I'll find out exactly which packs they use.

    Thanks!

    Denis

  6. #6
    Denis P.'s Avatar
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    I'm back with more info.

    Turns out they use Kodak chemistry in their Noritsu film machine, after all.

    The guy couldn't tell me exactly the Kodak codes for their minilab, but told me that they use replenished chemistry, so I'll also need a starter, etc.

    We finally agreed that perhaps it would be the best to get a 1 liter each (developer, bleach, fix and stabilizer) of already mixed chemistry, directly from the machine tanks No problems with activating the chemistry (no starter needed), and no problems with dilutions.

    I think that's the most practical way to do it, and we'll probably take that route.

    Now I just have to try to find color negative film in 4x5 format, which is not an easy thing these days....

    Regards,

    Denis

  7. #7
    Mick Fagan's Avatar
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    Denis, I think you should be fine with Kodak chemicals, after all they invented the C41 process.

    Regarding a pre-rinse for C41 as mentioned earlier, I'm not too sure that is a good idea, especially if you maintain the 3'15" first bath, which is the developer. Having a pre-rinse with C41 would mean a slightly longer time required in the developer.

    With the developer time being so short as it is, development time, along with active developer strength is really critical. By doing a pre-rinse with C41 you will be changing, what is an already tight process, to an unknown variable. I have never seen any commercial C41 process anywhere, that has a pre-rinse.

    To put the time thing into perspective with C41, adding 30 seconds to the first developer time, is a push of 1 stop.

    I have done a considerable amount of C41 in my CPE2 (with lift) and found that a strict 3'15" followed by a stop bath (optional), works wonders for consistent roll after roll or sheet after sheet, of C41 developing.

    Once you get a couple of processes under your belt, you may even think about push processing, although if you're shooting 4x5 I would think you wouldn't need to push the film. It is things like this that make developing your own film really worthwhile, plus you shouldn't get any scratches or footprints on your film.

    By maintaining a very strict developing process, you can see the effect of what a 1/3 stop (approximately) over exposure on grain size on every sheet/roll does (slightly finer grain). On the other hand, a very slight under exposure will coarsen the grain slightly. It is these variables, along with extremely consistent processing control, that can make really great technical control of the C41 process possible.

    Mick.

  8. #8
    Photo Engineer's Avatar
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    Using a prewet is just fine with C-41 in a jobo.

    In addition, Kodak suggests you use a wash between the bleach and fix.

    You only need a starter for the developer replenisher, for the rest you do not need starter.

    PE

  9. #9
    Denis P.'s Avatar
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    Thanks for all the info, guys. Much appreciated.
    I'll be sure to post the scans if anything comes out
    What I have in mind is a couple of color shots using some of my oddball lenses on 4x5 Speed Graphic... We'll see.



 

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