C41 Bleach help

Discussion in 'Color: Film, Paper, and Chemistry' started by Lopaka, Aug 5, 2008.

  1. Lopaka

    Lopaka Member

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    Well, we just had a discussion about the developer. Now for the bleach.
    The Bleach III 1 gal working solution is discontinued, the substitute for rotary processors is C41SM Bleach in a ready to use tank solution (packaged as two containers totalling 5.4 litres).

    The rotary tube processing instructions list bleach time (with Bleach III) as 6:30. The SM instructions - which are only for SM processors is 1 minute. So how do you use this stuff in the JOBO???

    Bob
     
  2. glbeas

    glbeas Member

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    Have you tried it out at 1 minute in the Jobo?, It's not like you can over bleach the film. Extend the time if you are running at a lower temp than the SM does.
     
  3. Photo Engineer

    Photo Engineer Subscriber

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    Use it for the full time of 6:30. This is not a shortie process and cannot tolerate any residual silver metal in the film if you want high quality. The water carryover in a Jobo is much greater than in conventional machines and it dilutes the fix considerably. Besides, extra time won't hurt.

    PE
     
  4. Lopaka

    Lopaka Member

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    Precisely the reason the JOBO instructions call for a rinse between bleach and fix. I just couldn't reconcile in my head 1 min vs 6:30. Thanks for your reply, I'll give it a go.

    Bob
     
  5. Lopaka

    Lopaka Member

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    Sources

    The 'replacement' bleach for rotary tube processing - SM tank bleach, which comes in a carton of 2 - 2.7 liter bottles ready to use (8824690) is still not being stocked by the usual suspects. Adorama is still attempring to locate some of the discontinued product. The only source I found that stocks this item is Pakor (makers of Pakosol):

    http://www.pakor.com/products/KODAK...90_444-1117.cfm?CFID=3119098&CFTOKEN=64627647

    Their service is fine, a phone call produces results and same day shipping. But I get nervous when there is only one source - I would like to continue using the Kodak chems but it is getting harder. Does anyone know of any other suppliers that stocks this in US?

    Bob
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    Bleach formula for C-41, use 7' at 100 F in a Jobo

    200 ml of 60% Ferric Ammonium EDTA
    10 g/l of Sodium EDTA (Disodium)
    10 g/l of Sodium Sulfite
    20 g/l Ammonium Bromide

    Adjust pH to 6.5 with 28% Acetic acid or ammonium hydroxide (any concentration from 3% to 28% will work but I prefer the 28%) as needed.

    7' 100 F Fix for C-41

    200 ml / L of 60% Ammonium Thiosulfate solution
    10 g/l Sodium Sulfite
    10 g/l Sodium EDTA (Disodium)

    Adjust pH to 6.5 as above.

    Capacity is the same as the Kodak variety, shelf life of this is the same as the Kodak variety. OMG, it is the Kodak variety, that is Bleach I and Fix I the originals, or as close as I can remember.

    All chemicals available from the Formulary.... And NO I don't get a cut or anything. They just happen to carry all of the above. :D

    Enjoy.

    PE
     
  7. PVia

    PVia Member

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    PE...

    You don't add water to make a liter or anything like that to the above recipe???
     
  8. Jerry Thirsty

    Jerry Thirsty Member

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    Is this to make one liter of solution? Because at Photo Formulary's prices, 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). Or does it make a liter of stock solution, which is then diluted to some working strength?

    Also, depending on whether I search PF for "sodium EDTA" or "disodium", I get either "ferric sodium EDTA" or "EDTA disodium salt", respectively, as the result. I assume you mean what they call EDTA disodium salt?

    TIA for the clarification
     
  9. srs5694

    srs5694 Member

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    I haven't looked at PE's formula carefully, but I did do some cost comparisons a couple of years ago, and bleaches based on ferric ammonium EDTA just weren't cost-effective to home-brew at the time, at least not given the cost of ferric ammonium EDTA from Photo Formulary, Art Craft, and other suppliers I could find. Presumably Kodak and other manufacturers of photographic bleaches have much cheaper sources of supply.
     
  10. Photo Engineer

    Photo Engineer Subscriber

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    That all is in g/l. What else can I say? You can start with 500 ml as the starting volume is irrelevant just so the final volume is not over 1L. You add the ingredients and add water to 1 L. Thats it. I would guess that you have no experience with chemical notation. I suggest Anchell and Troop or Haist for further reading.

    One problem since I posted that set of formulas. You may have sediment. At EK we used all Ammonium salts but they are very hard to get and expensive, so the sodium is used in my post. They may not totally dissolve. Not to worry! Just filter out the sediment. If you can get or make Ammonium EDTA or get Ammonium Sulfite, use that and you will have no sediment.

    Second.....

    Ammonium Ferric EDTA is hard to make and Kodak (K. Steven and J. Surash) own the patent. :D So, all of the Ammonium Ferric EDTA is made from the EK patent by adding Ammonium Hydroxide to Ferric Oxide and EDTA in a high pressure vessel with cooling. The result is a 60% NH4 Fe EDTA mixture at 60% which is the highest practical concentration available.

    So, when you buy this stuff it is expensive.

    Just remember, when we were developing this formula we had to start with all sodium bleaches, blixes and fixes and then redesign for ammonium equivalents. Our first solutions were hand made in the lab and not too pleasant for all of that.

    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. :D

    PE
     
  11. bill williams

    bill williams Member

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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!
     
  12. Photo Engineer

    Photo Engineer Subscriber

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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
     
  13. bill williams

    bill williams Member

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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!
     
  14. Photo Engineer

    Photo Engineer Subscriber

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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
     
  15. MattKing

    MattKing Subscriber

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    Ron:

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

    Matt
     
  16. Lopaka

    Lopaka Member

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

    Bob
     
  17. Lopaka

    Lopaka Member

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    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