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  1. #1

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    Jobo and C-41 question

    Hi guys,

    I've been doing my own B&W developing but never done color negative films.
    I just purchased the Jobo CPE-2 and Unicolor C-41 2 liter kit from freestylephoto to develop some color negative films and I'm confused.

    I'm planning to mix only the half ( 1 liter) so I could use my 1 liter accordion bottles and save some $.

    So,,, let's say I have my chemicals in 3 bottles (1 liter) and I want to process 4 sheets of 4x5 films in the 2521 tank then,,,

    1. I only need to get 300ml ready for each developer, blix and stablizer. Am I correct?

    2. Can I re-use them for 20 more times even though it says use it for 8 times on the box? I think I read it on other forum or somewhere.

    3. Do I keep the other 700ml in the fridge?

    4. After re-using the 300ml 20 times, then I get another 300ml from the 700ml bottle ( in the fridge) and use them for another 20 times?

    Please correct me if I'm wrong. Thanks!

  2. #2
    vedmak's Avatar
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    2. is wrong it says however many film capacity for entire 1 liter kit, not for a 1/3 of it. C41 does not keep more than 2 weeks when you make stock.
    Multum egerunt, qui ante nos fuerunt, sed non peregedunt.

  3. #3
    polyglot's Avatar
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    The chemicals have a certain capacity in terms of rolls developed per litre of chemicals. If you have two litres, you can do 2x as much; if you use 300mL, that 300mL will be good for 0.3x as much, etc.

    Separately from the chemical capacity, you want to minimise the number of times the developer is used in a rotary process because of oxidation; 5 times is probably the most you would ever consider doing.

    Yes, keep spare developer in the fridge. It should keep for a couple of months at 2C (the Fuji developer keeps for months in the fridge under butane; Unicolor I don't know). You can keep stabiliser in the bottle in a cupboard, no special storage required. Blix will kill itself in short order (the bleach eats the fixer), so try to mix up exactly as much as you need, immediately before use. This might mean you need to stockpile a few films and process them in a batch. If you can buy a proper C41 kit (like the Fuji) with separate bleach and fixer (not blix), it will keep much longer on the shelf.

    If you see people talking about capacities of 20+ rolls/litre, they're probably talking about the Rollei kit, which is NOT the same as the Unicolor kit.

  4. #4

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    Do not use accordion bottles! They breathe too much oxygen. Search for older threads for best containers for color chemistry. I keep my C-41 developer in full brown glass bottles in a fridge and the chemistry lasts for months.

  5. #5

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    Yes, the accordion bottles are crap. Just use a 300ml glas or HD-Polyethylene bottle.

    I am using the Digibase C41 / Fuji Hunt kit.
    For my CPA-2 with 2523 (used with elevator) I am using 300ml of chemicals.
    This has enough capacity for 6 C41 films. 3x2 135-36 or 120 roll films. The minimum volume in rotary for this tank is 270ml and it can be loaded with 2 films.
    I am using the chemicals (= working solution) up within 4 weeks. The concentrates you can keep for over a year. Only Part C (C41 developer) is more critical.

    Some people report the chemicals seems to be good over 3 months but like always it's not very wise to stretch the developer to the real end of lifetime. The Rollei Digibase C41 kits have different parts (A+B+C+starter) in C41 developer and seperate Bleach and Fixer and has a Stabilizer too.



 

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