alternative C41 Bleach formula?

Discussion in 'Color: Film, Paper, and Chemistry' started by ahock, Feb 13, 2009.

  1. ahock

    ahock Member

    Messages:
    37
    Joined:
    Feb 12, 2009
    Shooter:
    35mm
    I'm trying to brew the C41 at home. I have collect many recipe at this forum and start to order the compounds. But, I cannot find ferric ammonium EDTA at my country(Taiwan).

    Can I use other type EDTA to substitute ferric ammonium EDTA for C41 bleach? or if there have other bleach formula without use ferric ammonium EDTA?
    Thanks!!!

    Ahock Lo
     
  2. mts

    mts Subscriber

    Messages:
    372
    Joined:
    Feb 12, 2004
    Location:
    Los Alamos,
    Shooter:
    Multi Format
    There are alternatives that work well. If you like I can e-mail a collection of formulae that work well for me.

    The very simplest bleach that I tried and it does work for C-41 is cupric chloride. This bleach was explored by amateurs in the early 1980s for the same reason you are now seeking an alternative. Since cupric chloride is hard to find, there is an alternative that consists of 100g copper sulfate pentahydrate + 100g sodium chloride (iodized table salt is ok) per liter. In the US copper sulfate pentahydrate is sold in hardware stores in crystalline form as a chemical to discourage tree roots in sewer lines and is quite cheap. Sodium chloride is of course found in the kitchen. However, for some formulae (developers) you must not use iodized salt. For such formulae you can use what is sold in the US as canning or kosher salt, but not "sea salt" that has many other mineral components.

    Dissolve the two components in hot water and let the solution sit overnight to form about half the concentration of cupric chloride. It will be somewhat cloudy with a precipitate, so after sitting a day, filter the solution with ordinary paper coffee filters, and then use it to bleach. Be certain to follow development with a stop bath (2% acetic acid + 15-20 g sodium sulfite per liter) and a rinse, and then follow the bleach with another rinse before using a non-hardening fixer. The lifetime of this bleach is said to be near-infinite but of course it does gradually exhaust with usage.

    The copper bleach is certainly not ideal because you can expect a color shift in comparison with official processing, although the shift is entirely correctable in printing or scanning. Film processed this way is unlikely to achieve the long-term dye stability (whatever that is) produced by the Fe-EDTA bleaches.

    Another alternative is a quinone-persulfate bleach that I prefer and use exclusively for E-6 films, and that works quite well for C-41. It has the advantage of using components that are much easier to locate than the standard formulae.

    When using any alternative or scratch-mixing your chemistry from a proven formula, be sure to run tests to determine that the results are satisfactory. Take a roll of film of the MacBeth chart, or barring that, of a colorful scene for example a floral arrangement that has plenty of color. Cut off sections of the test roll to process individually to verify results. When testing bleach, fix, or blix formulae, you should follow development with a stop bath and a wash, and then bleach and fix in room light by inspection. Use a rinse in between the bleach and fix steps to reduce the carryover of bleach to the fixer.

    You should see bleach and fixers begin working within a minute or two and the action should appear uniformly complete by about half the specified bleach or fixing time (or the time should be regarded as twice what is required for the film to first appear uniformly bleached or fixed).

    For both C-41 and E-6 processed manually it is best practice to bleach and fix in separate baths precisely because you want to ensure by inspection that the processing for these steps goes to completion.
     
  3. mts

    mts Subscriber

    Messages:
    372
    Joined:
    Feb 12, 2004
    Location:
    Los Alamos,
    Shooter:
    Multi Format
    Correction: sodium sulfite should read sodium bisulfite. You need bisulfite in color stops and fixers to reduce dye degradation. I apologize for the mistake in the previous message.
     
  4. OP
    OP
    ahock

    ahock Member

    Messages:
    37
    Joined:
    Feb 12, 2009
    Shooter:
    35mm
    mts,
    I can order cupric chloride at my area. I would like to try cupric chloride formula. :smile:
    Thanks for your help!!

    Best,
    Ahock
     
  5. mts

    mts Subscriber

    Messages:
    372
    Joined:
    Feb 12, 2004
    Location:
    Los Alamos,
    Shooter:
    Multi Format
    Post results of your experiments and let us all know the result.
     
  6. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Either sulfite or bisulfite can be used in color fixers or stop baths as long as the pH is properly adjusted. This is normally about 6.5 to preserve the color dyes at the proper pH.

    The sulfite itself (or bisulfite) is used as a color coupling stop chemical that destroys color developer and prevents further dye formation. In that sense, the sulfite (bisulfite) ion acts as a type of color stop bath.

    To demonstrate this, put some color developer into an acetic acid stop. If you shake this mixture, it will turn pink. Add a pinch of Sodium Sulfite and it will instatly turn colorless as the oxidized quinone diamine form (oxidized) reacts with Sulfite ion and forms the paraphenylene diamine sulfonate.

    This same reaction occurs between Sulfite and oxidized HQ in B&W developers but is not highly colored, and is rather meaningless in B&W as no dyes are formed. All it does is removed HQ, but in staining developers it reduces or eliminates stain.

    Just an FYI note.

    PE
     
  7. mts

    mts Subscriber

    Messages:
    372
    Joined:
    Feb 12, 2004
    Location:
    Los Alamos,
    Shooter:
    Multi Format
    Thanks for clarifying this point! The message is that a sulfite-containing stop and rinse is best practice for all color processes.
     
  8. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Actually, since the blix in RA and the bleach in C41 contain sulfite, I just use an acid rinse if I need one.

    PE
     
  9. OP
    OP
    ahock

    ahock Member

    Messages:
    37
    Joined:
    Feb 12, 2009
    Shooter:
    35mm
    PE,
    For the alternative bleach formula, do you think the following work?

    Diammonium EDTA 359g
    Ferric chloride 162g
    Ammonium Bromide 50 g
    Ammonium Sulfite 10 g
    Disodium EDTA 10 g
    Water to 1 liter. Use for 7 minutes at 100F.



    Thanks!!
     
  10. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Ahock;

    IDK the molar equivalents offhand, and so I would have to just say it looks right. There should be a 1:1.1 molar equivalence to the Ferric ion and the EDTA with a 10% excess of EDTA as expressed. There should always be a slight excess of about 10% in the EDTA. The pH should be 6.5.

    PE
     
  11. OP
    OP
    ahock

    ahock Member

    Messages:
    37
    Joined:
    Feb 12, 2009
    Shooter:
    35mm
    PE,
    Thanks! Beside, is there any method to test whether the bleach works?

    Thanks!!
     
  12. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Sure there is a test method. Stick a piece of processed B&W negative into the bleach and let it go for about 10 minutes. The image should almost completely vanish. Then, fix the film and the image should be gone. There may be a faint ghost image remaining due to some insoluable salts that form or due to distortion of the gelatin, but the film should be clear with no brown dmin.

    PE
     
  13. OP
    OP
    ahock

    ahock Member

    Messages:
    37
    Joined:
    Feb 12, 2009
    Shooter:
    35mm
    WOW, very helpful!!! Thanks!

    From another thread, I read the test method of fix solution by you. I wonder is there any test method of developer solution?
     
  14. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Of course. That has been discussed in many threads.

    First, check out a piece of film or paper by fogging it in the light and then developing for a specified time and temperature. This is a fresh developer test. You may want to develop more than one piece for more data.

    With that time recorded, any time later on that you want to test the developer just run the same test and if the paper or film fails to get the same densities at the same times then the developer is bad. Up until that point, the developer is still good.

    PE
     
  15. mts

    mts Subscriber

    Messages:
    372
    Joined:
    Feb 12, 2004
    Location:
    Los Alamos,
    Shooter:
    Multi Format
    At risk of being accused of passing gas in church, here is another contribution to C-41 bleach alternatives.

    The two images attached are negative scans from Portra 160NC 35 mm film processed identically save for the bleach. After developing (alternative C-41), and stop bath and rinse, I snipped off a few frames of the MacBeth chart and then completed processing the two samples using the traditional Fe-EDTA bleach for one and the copper bleach formula I mentioned above for the other. Bleaching was done to completion by inspection at ~100F temperature (7 minutes for the iron bleach and 10 minutes for the copper), followed by a rinse and the usual fixer/wash/stabilizer.

    The copper bleach is the 100/100 g copper sulfate/salt per liter that I mentioned above. The images are negative scans made with Nikon LS-9000ED at 600 dpi. To the eye the negatives have nearly identical appearance.

    My conclusion is that if the stimulus works as well as copper bleach we will soon be in pretty good shape. I am not advocating replacing conventional bleach formulae with the simpler one, but for those who cannot afford or locate components for iron bleach it does work. Who knows about long term dye stability? All I know is that these negatives haven't faded in the last 12 hours.
     

    Attached Files:

  16. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    These are scans. Did you measure the Dmin of your negatives?

    We used to get retained copper salts in the coating. We could also get image dye destruction in some films.

    PE
     
  17. mts

    mts Subscriber

    Messages:
    372
    Joined:
    Feb 12, 2004
    Location:
    Los Alamos,
    Shooter:
    Multi Format
    I have no densitometer access and did not measure DMin. Perhaps it could be estimated with the older Nikon LS-3500 scanner that can be used more or less as a poor man's densitometer. The copper bleached film might look just a bit denser to my eye, but a measurement would be useful. If you like I can mail you the negative strips.
     
  18. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    I don't have a really good quality color densitometer. I have a very old Kodak model from the 50s in which you match the two halves of a colored dot by eye and then read the density from a plastic disk.

    One way to test any bleach is to use it for color paper. If the dmin is off, you can really see it.

    PE
     
  19. mts

    mts Subscriber

    Messages:
    372
    Joined:
    Feb 12, 2004
    Location:
    Los Alamos,
    Shooter:
    Multi Format
    Can measurements be made with a color analyzer to at least determine relative densities? I can do that if it seems warranted.
     
  20. OP
    OP
    ahock

    ahock Member

    Messages:
    37
    Joined:
    Feb 12, 2009
    Shooter:
    35mm
    I try to prepare bleach with the following formula:

    But after I mixed Diammonium EDTA and Ferric chloride, the solution have yellow precipitation. here is the picture..

    [​IMG]

    Do you think this is normal phenomenon? Thanks!!
     
  21. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Check the pH. If it is too alkaline, then ferric hydroxide or oxide can form. This is a hopeless case. If it is too acidic, then EDTA salts can precipitate out. Adding ammonium hydroxide (28%) will help as long as the pH does not go over 6.7.

    But no, this is not normal at all.

    PE
     
  22. OP
    OP
    ahock

    ahock Member

    Messages:
    37
    Joined:
    Feb 12, 2009
    Shooter:
    35mm
    PE,
    Thanks!!!

    I have check the pH with quick test paper. It is acidic solution. I try to adjust the pH with ammonium hydroxide and check the pH with pH meter. The precipitate start soluted when pH reached 5.5. The solution become clear and dark reddish when pH beyond 6.0.

    here is the picture:
    [​IMG]


    If I change the powder adding order as below:
    Ammonium Bromide
    Ammonium Sulfite
    Diammonium EDTA
    Ferric chloride
    Disodium EDTA

    adjust pH to 6.5

    Do you think this will help to prevent aggressive precipitate occur?

    Besides, what is the life time of the bleach solution or how many film we can developed with 1L bleach solution?

    Thanks!!
     
    Last edited by a moderator: Mar 3, 2009
  23. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    I cannot say if the addition order will help, as it appears to be a pH problem that will take place with this mixture. As for capacity, as long as you keep bubbling air through it and replenishing with Ammonium Bromide, this solution will last a long time. How long is a guess, depending on how well you treat it in terms of carryover from the developer and etc....

    Make sure that your pH is between 6.3 and 6.7 though.

    PE
     
  24. OP
    OP
    ahock

    ahock Member

    Messages:
    37
    Joined:
    Feb 12, 2009
    Shooter:
    35mm
    Really amazing!!
    Can you explain the working theory? Thanks!

    How often should we replenishing Ammonium Bromide? and, should we filter the solution after "refresh"? Thanks again!!!
     
  25. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Sure....

    NH4Fe(EDTA)[ferric] + Ag metal + NH4Br -> NH4Fe(EDTA)[ferrous] + AgBr + NH4OH. There is a slight pH rise.

    with Oxygen, you regenerate the Ferric form all over and with more Ammonium Bromide you replenish the halogen. The pH will drop in this case back to close to the original. But, you must keep track of the pH and you must keep track of any developer carried in. Addition of more Sulfite and Na2EDTA may be needed if you see an increase in stain in the final pictures.

    PE