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  1. #11

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    Quote Originally Posted by fotoobscura View Post
    MtJade,


    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)?
    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.

  2. #12

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

    Regards!

  3. #13
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    Quote Originally Posted by Diapositivo View Post
    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.
    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.
    Paul Schmidt
    See my Blog at http://clickandspin.blogspot.com

    The greatest advance in photography in the last 100 years is not digital, it's odourless stop bath....

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