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  1. #1
    Diapositivo's Avatar
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    Final checks before first C-41 process

    Hallo,

    I have a certain experience now with E-6, which I practice since last October, thanks also to the precious help of this site. I want to begin processing C-41 as well, and have ordered the Rollei / Compard Digibase C-41 5-litre kit.

    With E-6, I use a Jobo CPP-2 with lift. I use mostly a Jobo 1510 tank (1 roll at a time) prepare chemistry one-shot, use the same chemicals for 2 processes, then discard all the 6 baths (that would mean 2 films with 140 ml final solution). When I use the Jobo 1520 (2 135/36) I would prepare 240ml, use twice (4 135/36 in total), then discard all the 6 baths. At the moment I only reuse the stabiliser.

    I have some questions regarding the Digibase C-41 kit.

    1) Declared capacity is different for colour developer and the other baths. Using a Jobo 1510, the instruction sheet says the capacity is 2 - 3 films for the colour developer, 3 - 4 films for bleach and fix, and 8 film for the stabilizer. When using one-shot chemistry, suppose I want to use colour developer 2 times and bleach and fix 3 times, I should:

    Prepare 140 ml of each bath;
    Make two processes, then discard only the film developer and prepare new one;
    Make one process, then discard bleach and fix;
    Make one process, then discard developer and prepare a new one;
    Revert to line 1.

    That's impractical. I am going to process E-6 also and don't want to keep too much accounting regarding what is what and how exhausted it is. I would like to prepare baths, use them within one or two days, then discard everything but the stabiliser.

    So the first question is: 3 processes with Colour developer give real quality, or are there any risk with quality, considering that I will be using a rotative processor, which means a lot of swirling and mixing with air during treatment, i.e. a lot of oxidation? The degree of quality that I aim to is the one obtainable by using E-6 one-shot chemistry only twice and then discard. I see no difference at all between the first process and the second one.

    That would allow me to prepare all the baths, use them 3 times possibly within 24 hours or so, and discard all of them, using the colour developer at its "maximum" advised capacity and bleach and fix at their "minimum" capacity. I would process either 3 rolls (1510) or 6 rolls (1520) making three processes with each chemistry dilution and then start again with newly-mixed chemicals.

    1 bis) As an alternative, could I dilute the bleach and fix more than per instruction sheet, so that I use them only twice, and proceed as I do with slides, i.e. "two-shots" and then discard chemistry? How much should I dilute bleach and fix?

    2) In what does a stabiliser for C-41 differ from a stabiliser for E-6? Can I indifferently use my E-6 stabilizer (stabiliser proper, it contains formalin and hardener) with C-41, and Rollei stabiliser (contains 1,2 benzoisothiazolin-3-on, whatever that means, and does not contain formalin) or should I keep two containers for the two different treatments?

    Thanks
    Fabrizio
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
    Stock images at Imagebroker: http://www.imagebroker.com/#/search/ib_fbr

  2. #2
    Diapositivo's Avatar
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    And by the way, should I extend processing time when reusing the chemistry? The manual makes no mention about that.

    When it says that with a Jobo tank 1510 (rotary processing) I can process 2 - 3 films, it obviously means in different processes, as the 1510 can process only 1 film at a time. But it gives no instruction regarding treatment time.

    3:15; 3:15; 3:15 ?
    Or 3:15; 4:15; 5:15 ?

    Please help
    Fabrizio

    PS the manual is here:
    http://www.macodirect.de/download/C4...tionManual.pdf

    and as noted in another thread it does not even mention the rinse between bleach and fix.
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
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  3. #3
    markbarendt's Avatar
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    Bleach and fix actually keep very well. Aeration is actually good/expected/preferred/needed for the bleach. Exhaustion is the bigger issue. No reason to discard early.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Ana´s Nin

  4. #4
    Diapositivo's Avatar
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    Thanks Mark. I think I'm going to buy another set of Jobo flasks, with proper air-tight lids (my Jobo flasks don't have lids at the moment, that's how I received them from the seller of the machine) and apply the exhaustion accounting for bleach and fix.

    I searched through the site again regarding reuse times (using "C41 reuse" as keywords, lots of info). People says things like increasing time after X rolls, but don't specify the way they use their chemistry (how much they prepare, use, pour back in the flask, how much real reuse is that).

    The time increase appears to be small, something like:
    3:15; 3:30; (3:45 for a third process).
    or even:
    3:15; 3:23; (3:31 for a third process).
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
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  5. #5
    markbarendt's Avatar
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    With regard to the time I don't normally run the developer to exhaustion, I replenish so my times remain constant.

    I have on occasion an extra roll at the end of the day where I have nothing left to replenish before dunking it. I still do the roll as long as I have enough to cover. Seems to work with either normal and extra time.

    In your shoes I'd probably add 15 seconds or so for each subsequent bath and see if that works. I'd also do the more important rolls in the 1st 2 baths.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Ana´s Nin

  6. #6
    polyglot's Avatar
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    I would not trust the Jobo flasks for storing chemistry as they are of the soft kind of plastic that is likely to be oxygen-permeable. PETE or glass bottles, either squeezed to get the liquid to the cap or butane displacing the air, should give you better longevity. I plan to store my 1L of developer working solution in the fridge (to reduce oxidation rate).

    I believe the Rollei kit is just Fuji chemistry (I read it on APUG, it must be true!). I recently bought the Fuji 5L kit and it says you get 16 rolls per litre of chemistry; people here report that it works well long after that point. You need to increase the development time after every 20% of the capacity of the working volume you're using, and the increases are very small: 3:15, 3:18, 3:23, 3:29, 3:40 (that last one might be wrong). You can find the Fuji instructions scanned and posted in another thread around here somewhere. The times published assume that the exhaustion occurring in one batch is small compared to the total capacity of the chemicals, i.e. that you're using much more chemistry than the "one shot" minimal amount. The Fuji instructions suggest doing 5 batches of 16 films in 5L of chemistry, which means that you want at least 300mL of chemistry per roll otherwise the reduction in activity within one process will mean you want a longer processing time than indicated in the table.

    Say for example, you mix up 625mL of chemistry (enough for 10 rolls at the rated capacity) and process two rolls at a time with all of chemistry. Your processing times for the 5 pairs of rolls should (nominally) be 3:15, 3:18, 3:23, 3:29, 3:40. Alternatively, you could do one roll at a time; you would put in about 350mL of chemistry, do the process at the time for that roll-number, then mix the recovered chemistry back with the other 275mL. This is because the chemistry doesn't care whether you're running a 16 roll batch in 5L or a 2 roll batch in 625mL - it's the same amount of chemistry per film.

    Or you could replenish; I haven't done it with colour but I believe it works like this:
    - make up a batch of chems (working stock), at least 300mL * concurrent rolls (e.g. you want to soup 6 rolls at once, make up 1.8L of chems)
    - make up some more chems (replenishment stock)
    - run a batch of rolls in the working stock for 3:15 (probably)
    - throw out 62.5mL of working stock per roll processed and replace it with the same quantity from the replenishment stock

    That 62.5mL is 5000mL/80, i.e. the replenishment rate that will get you the same capacity as reuse. Arguably you could push (reduce the replenishment rate) this further and more safely than you could push non-replenished re-uses.

  7. #7
    Diapositivo's Avatar
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    Let's suppose I am doing one roll at a time, in 140ml of working solution. The exhaustion of those 140ml after one roll has been developed in it is much higher than the exhaustion of making, as in Polyglot's example, 2 rolls in 625ml. In my case, it's 140ml per roll. In Polyglot's case, is 312ml per roll. That means the exhaustion should be more than double.

    I guess I'll have to experiment, increasing somewhere between 8 and 15 second for each process.

    I'll measure the final volumes of each bath the kit provides. I read that somebody uses C-41 developer only once, and somebody only twice. So I think I'll give up on the third process in the same developer since now, and concentrate on organising for "asymmetrical" mixing which is a bit of a nuisance (getting more flasks, pouring from flask to flask, keeping track without making dangerous mistakes).

    The Jobo flasks are simply marked as PE. I don't know if they mean HDPE or LDPE. From my notes, developers should be preserved in plastic #1 (PET, PETE) or #3 (PVC), while bleach and fix should be preserved in plastic #2 (HDPE, PE-HD) or #4 (LDPE, PE-LD) where high density is preferable to low density. So the Jobo bottles should be "adequate" for the preservation of bleach and fix, which will allow me to avoid pouring between containers.

    The idea is: within 24 hours or so I do all the process (2 or 3, that's to determine) and discard the developer. I'll keep bleach and fix in the Jobo bottles until I make a new process.

    I'll go shopping for Jobo flasks.

    Thanks
    Fabrizio

    PS The Rollei Digibase kit is produced by German producer compard (yes, with small case c it appears) according to its instruction manual.

    compard KG
    Mercatorstra▀e 65
    D-21502 Geesthacht
    Germany

    APUG is not a reliable source of information when it comes to who manufactures what
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
    Stock images at Imagebroker: http://www.imagebroker.com/#/search/ib_fbr

  8. #8
    Diapositivo's Avatar
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    And what about water?

    For E-6 I use normal tap water as I've read here on APUG that it is better than demineralized water. In E-6 process I only use demineralized water in the stabilizer.

    The instructions for the Rollei Digibase kit say that although tap water is acceptable, demineralized water is better. Normally I would blindly follow manufacturer's direction but in this case I am a bit reluctant. Maybe they say that only as a "disclaimer" in case of use of tap water which has certain undesirable characteristics. The case may be that "normal" tap water is still better than demineralized water.

    Which water do you use?

    Fabrizio
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
    Stock images at Imagebroker: http://www.imagebroker.com/#/search/ib_fbr

  9. #9
    markbarendt's Avatar
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    Yes the 140 will exhaust quickly, if it were me using your chems, I'd run 1 roll in the first 140 and then only keep 90-100 of the used solution and add 40-50 ml of fresh to get back to 140 for the next roll.

    I always use distilled water for mixing chemicals, it's just one less variable, I do wash in tap water but the film is always finished in stabilizer that was made with distilled water.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Ana´s Nin

  10. #10
    polyglot's Avatar
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    140mL is about 2x 62mL, so (if the capacity is same as for Fuji), the chem would be about half exhausted, requiring a dev time of 3:23 instead of 3:15. So anywhere around 3:20 ought to be fine; I don't think you can time it nearly that accurately anyway what with fill-time and time waiting for the stop to go in. Fuji says the 3:15 includes 10s of pour time but they say nothing about dev sitting on the film after dumping the bulk of the dev out.

    The instructions for both Fuji and Rollei both say to reuse, so I don't see much point in one-shotting. Pro labs do the replenishment thing and they (if run properly) get perfect (i.e. within process definition) results.

    Edit: if you go look in my C-41 overdilution thread, there's someone using dilute RA-4 to (apparently successfully) soup film. So the process might actually be kind of forgiving. I suspect that the minor variations in time and developer activity that we're discussing are irrelevant. You probably need to stuff up badly to cause crossover and if you're hybrid, that still doesn't really matter.
    Last edited by polyglot; 06-26-2011 at 10:45 AM. Click to view previous post history.

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