Several c41 questions..

Discussion in 'Color: Film, Paper, and Chemistry' started by fotoobscura, Sep 20, 2012.

  1. fotoobscura

    fotoobscura Subscriber

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    Afternoon everyone!

    So, how important is is really to blix at 95-105F? I've been blixing anywhere from 65-80 (whatever the room temperature is) with literally no (observable?) impact on the negatives (granted I haven't taken out my densitometer, but they scan fine...)

    Second, I intentionally skipped stabilizer on a few rolls and I am seeing zero impact on the output months later (I scanned the roll fresh out and again months later with no appreciable differences)...Is stabilizer really necessary for modern color emulsions? Is it really preserving the dye couplers from turning brown in modern films?

    Third, with respect to dilution of c41 developer: Is there a sense or understanding of how much c41 developer can be diluted to produce a "quality" image? I've been experimenting with color stand development for the last few years and have had very good (and reproducible if semi-stand) results from 1:4 - 1:9 dilutions to 650ml. One shot, of course.

    Fourth- I read somewhere (and subsequently tried) to fix c41 in bw fixer and although the image "fixed", the "bypass" effect I was interested in was essentially an opaque negative. Is bleach bypass literally just bypassing the bleach process? I can't see how there would be any latent image without getting rid of all those sulfides...I eventually blixed the roll at room temp and it cleared nicely in a few minutes..

    Finally, does anyone know if color film reticulates like bw film when the apply exceedingly high temperatures to it?

    Thanks in advance for your answers and also for not trolling me by asking me "why the hell would you do that?" :smile:
     
  2. pentaxpete

    pentaxpete Subscriber

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    I have not stabilsed many C41 rolls for some time as I ran out ! HOWEVER -- on one roll of 120 XP2 Super I did a year ago I notice some uneven 'brown' effects compared with the usual more 'Magenta' colour
    Regarding RETICULATION -- YES -- Ilford XP2 Super and their FUJI equivalent DOES reticulate easily on the backing super-coat if a 'PRE-SOAK' is used and also if you RINSE quickly with water at 100oF between the Developer and the Bleach, so it is really necessary to go straight into the Bleach from the Developer. I have NOT had any Reticulation of COLOUR C41 emulsions under those condtions of pre-soak and rinse.
     
  3. pentaxuser

    pentaxuser Subscriber

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    I think there is quite a large of temps for blix without ill effects as you have demonstrated. Not using a stabiliser might give problems many months down the line. That is months which equate to several years because I understand stabiliser to prevent "bugs" attacking the emulsion.

    pentaxuser
     
  4. fotoobscura

    fotoobscura Subscriber

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    Thanks to both of you for the replies..

    My process is as follows:

    3. Pre-soak ~39C for 1-3m depending on my impatience
    2. Develop at ~39C for 3.5m
    3. Rinse 4-5x tap water, 25-30C
    3. Blix 6.5m (give or take) at room temperature (varying between 20C-25C during the Summer)
    4. Wash 10m, tap water, 25-30C
    5. Pflo 1m

    Would anyone like to chime in on the stabilizer and bleach bypass questions?

    Best regards and Thanks!
     
  5. Simonh82

    Simonh82 Member

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    As others have said the stabilizer is a necessary step to stop fungal/bacterial attacks on the film. This may only occur after many years, but could ruin your negatives in the long run. Stabilizer is also said to stabilize the dyes in the film, although this is no longer necessary as C41 the film has had stabilizer built in for the last decade or so. There is an interesting post here about it http://www.apug.org/forums/forum40/104349-definitive-word-i-hope-color-stabilzers.html. Stabilizer is not necessary for B&W as the silver has natural anti-bacterial/fungal properties.

    Bleach bypass is not a technique i've played with myself, but my understanding is that it is often just reduced time spent in the bleach rather than totally skipping the step altogether. As you say this would end up with very dense negatives.

    As far as the temp of the blix stage goes, I imagine there is plenty of scope in the temperature you use, but if you are heating up the developer, why not do the blix at the same time. Blix times extend considerably as you reuse it and having it at higher temperatures may help to keep the times within reason.
     
  6. fotoobscura

    fotoobscura Subscriber

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    Simon,

    Good point on the Blix. I suppose I could. It is a lot easier for me to worry about only heating up one of the two. Obviously the developer temperature is more important than the blix so that's what I chose to heat up. I don't mind heating up the blix at the same time, I'm thinking I will just stop keeping tabs on the exact temperature (which is usually my procedure)..I've also noticed when I do a quick one-off roll or two using bw tanks that the temperature of the chemistry causes, I think, the plastic to slightly swell which in turn causes leaking when agitating....This doesn't happen when the chemistry is at room temperature..

    Finally, is there an idea on just how much bleach one is supposed to use for the bypass process? Ratio, or?

    Thanks.
     
  7. mtjade2007

    mtjade2007 Member

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    First of all develop at 38 degree C for 3 min 15 sec, not 39 degree C for 3 min 30 sec.
    Skip the rinse in step 3. It is not a good practice to rinse between development and bleach.
    Separate blix into bleach and fix. It is not good to blix C-41 films.
    Instead of Pflo in step 5 use a stabilizer or Kodak C-41 Final Rinse. This is a critical step. Final Rinse is very cheap. Don't skip it or change it.
     
  8. Gerald C Koch

    Gerald C Koch Member

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    Using a water bath makes it very easy to keep processinging solutions at the right temperature. If you vary from the recommended processing either with temperature, agitation, dilution, etc you are not going to get optimal results.
     
  9. fotoobscura

    fotoobscura Subscriber

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    MtJade,

    That sounds like perhaps instructions for a rotary and different chemistry. I'm not using a rotary. I usually buy Tetenal press kits which prescribe in fact 39C for 3.5M.

    Could you please humor me and explain to me why it's not good practice to rinse between developer and bleach? (especially if the rinse temperature is near developer and blix temperatures)? Both developer and blix can be reused repeatedly. It occurs to me rinsing after the developer ensures less/little developer is introduced into the blix when it is stored. I have been doing it this way for many years with no ill effects. But I'm always looking to learn a thing or two! (or ten!)

    Relatively recent example using my above mentioned process:

    http://www.flickr.com/photos/9093035@N06/8009472514/in/photostream/


    Thanks!
     
  10. Diapositivo

    Diapositivo Subscriber

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    In theory some residue of developer will benefit the bleach bath as it creates the right pH. In practice if you want to reuse bleach without polluting it the better solution is an "acid stop" bath which serves both purposes, make an acid environment and avoid polluting bleach with developer. That's what I read here on APUG. Your mileage may vary.

    "Acid stop" can either mean acetic acid or citric acid.

    From my notes:
    Acetic acid: economical, effective, not risky for the film, dangerous for persons, polluting, stinking, reusable, well preserved; can be used more times when diluted at 2%. For one-shot better using 1% or 1.5% dilution.

    Citric acid: more expensive, not dangerous, odourless, must be used on the same day of dilution, and some people report the possibility of problems (my notes not very specific).

    I chose acetic acid. I still have to perform my first C-41 bath, my "chemistry" is still sealed. Hope I'll do it in the next few weeks.
     
  11. mtjade2007

    mtjade2007 Member

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    The film will continue to develop during the rinse. Unless you use a stop bath but then it will affect the PH of the bleach that can be a hassle for rusing the bleach.

    There have been a number of posts by PE in the past explaining why Blix is not ideal for C-41 process. I have also seem reports of problems using Blix in C-41 process. For some reason Tetenal C-41 kit continues to use Blix. C-41 is a proprietary process shared by Kodak and Fuji. There are reasons why it uses a bleach followed by fix. For optimal results I will use only Kodak or Fuji C-41 chemicals and follow the standard procedures to develop at 38 degree C for 3 min 15 seconds. I will bleach and fix then followed by final rinse with a Kodak final rinse chemical.
     
  12. fotoobscura

    fotoobscura Subscriber

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    Very interesting. Thank you for the information. I will try to dig up PE's posts.

    Regards!
     
  13. wogster

    wogster Member

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    There are a couple if things that are not quite right in the above.

    1) Developer is a base, or alkali, this means that a developer will increase the PH, until it's either neutral (7) or higher. An acid stop will keep an acid bleach an acid.
    2) Acetic acid is what gives vinegar it's kick. The dilutions used in photography, typically 1% to 2%, is actually lower then that used for cooking use, typically 5% to 8%. This means if you run out of stop bath, go to the kitchen, grab the white vinegar from the cupboard and cut it 1+4 with water and you have a stop bath. If you have higher concentrations then for household use, it could be dangerous. Most acetic acid for stop bath is produced chemically these days, it's not the acid that could be dangerous, it's the impurities that could be in it, from the chemical process. Not much you can do about the smell. Another option would be to pick up a bottle of Ilford odourless stop bath, which is citric acid, mix according to the instructions and you should be pretty close. Mix according to need, in other words if you need 250ml of solution, mix that amount.