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Thread: C41 Bleach help

  1. #11

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    PE, you have stated more than once that the bleach for C41 should have a pH of 6.5. Your's is not the only statement as such, as there are at least a couple of others that have referenced 6.5 as the proper working pH for c41 bleach. I have a couple of Kodak references that say the pH for flexicolor III should be 4.5 to 5.0 for a fresh or seasoned tank, and 4.25 to 4.75 for a replenished tank. One reference is the Kodak Professional Reference Dataguide, Cat 193 4777. I've measured a fresh mix of my kodak flexicolor bleach III with a Hanna pH checker and found it to be in the 4.5 to 5.0 range. I'm I reading something wrong or have I got myself confused about which bleach is which. I appreciate any clarification. Thanks!

  2. #12
    Photo Engineer's Avatar
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    You are apparently correct. The Bleach III is based on NTA (Nitrilo Triacetic Acid) which can use a lower pH. The bleach that I have referenced, as I noted several times is the original, slower EDTA bleach. There have been complaints about the price of Ferric EDTA, well if you knew the price of the NTA to make your own, you would be rather upset, from what I understand.

    A good bleach can be made from either, but the lower the pH, the more active it is. However, the carryover into the fix can cause problems. Remember, one is an oxidant and the other is a reductant. As pH goes down, the oxidant becomes stronger and bleach times go down.

    PE

  3. #13

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    I'm ok then with the kodak flexicolor III bleach at 4.5-5.0.

    I believe that one of the documents that referenced a pH of 6.5 was a trouble shooting guide for problems encountered by one-hour labs, so I guess they likely were not using Kodak Flexicolor Bleach III. Or perhaps it was an old publication.

    Thanks PE!

  4. #14
    Photo Engineer's Avatar
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    Well, Bill, there have obviously been 3 variations on this bleach. I know version I by heart, and I know of the NTA work by Keith Stephen, but I cannot give you details on II and III. Sorry. I know generalities but not details.

    PE

  5. #15
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    Quote Originally Posted by Photo Engineer View Post
    I just wish I had a penny for every liter (or gallon) of my blix concentrate sold. If so, I would not be on this forum or teaching workshops. I would own a tropical island somewhere.

    PE
    Ron:

    Are you sure you wouldn't own a chunk of Rochester, instead? .

    Matt

  6. #16
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    Thanks, PE, I will keep the formula on file for future reference.

    Bob
    "I always take a camera, That way I never have to say 'Gee, look at that - I wish I had a camera'" -Joe Clark, H.B.S.S.

  7. #17
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    Quote Originally Posted by Jerry Thirsty View Post
    .......it seems awfully expensive (about $32.25 per liter ?? if I'm estimating right) compared to e.g. Adorama's $26.50/gallon of Flexicolor Bleach III (assuming they actually had it in stock).
    Adorama does NOT have it in stock, in fact the buyer is still telling the sales people that they can find some. I have an outstanding back order and have received emails apologizing for the delay saying they still expect to receive it. I doubt it.

    As far as cost, the old Bleach III with shipping worked out to about $10/liter. The SM tank bleach with shipping works out to about $16/liter. So costs keep going up in leaps. The bleach is the expensive part of the process, C41 fixer is about the lowest cost fixer around and easy to get.

    Bob
    "I always take a camera, That way I never have to say 'Gee, look at that - I wish I had a camera'" -Joe Clark, H.B.S.S.

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