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  1. #1

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    C41 Bulk Mixing Failure: Should I abandon bulk?

    I guess it was ambitious.....ie using bulk chemicals for my first attempt at C-41. My reasoning was I had inherited from a friend a large quantity of bulk chems (albeit very old) which I just had to augment with a few more bulk purchases.
    I followed this recipe and returned a terrible result:

    Click image for larger version. 

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    (in fact that was my 2nd attempt after a blank neg the first time around!)

    Due to my inexperience and the fact that I'm using a mixture of old and new chemicals I don't know where to begin in terms of troubleshooting so my question is, should I abandon efforts at Bulk mixing and go kit or are there some obvious troubleshooting moves I can make?
    Last edited by HumbleP; 01-27-2013 at 10:54 PM. Click to view previous post history.

  2. #2

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    The bottom part looks sort of "unfixed" to me. Why don't you try fixing it some more?

    The uneveness, etc, sort of bothers me, what is your method of processing (standard tank, or your own machine, etc)? Do you have previous experience developing film, or is this a first? (If you've done good quality previously, this would show that you understand the basic technique.)

    Note: it's probably better to describe your method as "mixing from chemical components," or the like, rather than from bulk chemicals. To me, "bulk" means relatively large quantities

    If you don't have a way to screen all of your chemicals, and are not experienced with the C-41 process, it might be a good idea to initially buy a small quantity of a commercial mix. One by one you can try swapping your homebrew chemicals in place, to see if it gives the same result.

  3. #3

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    Thanks Mr Bill,

    Yes I'm mixing from Chemical components.

    I've been developing B&W with success (although I didn't mix my own developer)

    I'm using a Patterson tank employing a Hot Tap method for temp control (I'm pretty sure I got that part right)

    Your comment on the fixer has got me thinking....I was unable to source Ammonium Thiosulphate and am using Sodium Thiosulphate instead. I understand this is much slower and having no idea how much to use I began by adding small quantities and testing the fix time using off cuts from film ends. Eventually I ended up adding about 80g of the Sodium Thiosulphate and still had a very long fix time (Close to 10 minutes!)

    I don't know if anyone can shed light on this any further. Perhaps I should increase the quantity of Sodium Thiosulphate even further?

  4. #4

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    Typically sodium thiosulfate fixers for film contain 200 g/l. So one containing only 80 g/l would be rather slow. In addition sodium thiosulfate is slower in removing silver halide than the ammonium salt.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  5. #5

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    Thanks Gerald.
    That is at least something concrete I can try.
    I'll report back

  6. #6
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    C41 developer is so extremely cheap I don't know why you'd bother. By all means save money on the bleach+fixer - they're more costly yet chemically simpler and with much less effect on the image quality if you get them approximately right.

  7. #7

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    Dear humble!

    I have no idea, how the developer composition came to that filmprocessing.com site, in fact I brewed that composition a while ago…
    This is the original thread.
    http://www.apug.org/forums/forum40/5...-near-c41.html


    The Developer works near to perfection, definitely comparable to stuff you can buy. The real trick is to be extremely correct in weighting the ingredients out, because only small deviations will lead to different activity and pH. A good scale is mandatory! A calibrated pH-meter no fault.

    If you do use the formulations from the filmprocessing website, especially the proposed ferricyanide bleach the stop/clearing Bath is absolutely mandatory!! The bisulfite will catch developer residues and make them water soluble to prevent fogging due strong oxidants (ferricyanide).
    So you should prewarm, develop, than stop/clear for 2 min. than rinse for 2 min. and then bleaching. After bleaching again a 2 min rinse, then to the fixing step followed by a good wash.

    If you are unsure about the bleaching and fixing times, extend them to 6 min bleach and 8 to 10min fix, follow Geralds proposal with the increased sodium thiosulfate ammount, this is absolutly necessary!

    Regards, Stefan

  8. #8

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    Stefan,

    Thanks for referring me to the original thread. That site you referred to is my blog. I've fixed with a credit to you now!

    I've got a few things to fix (better scales being one)

    Will report back.

    Many thanks.

    Regards,
    Peter

  9. #9
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    Do not ever try to fix C41 in a Sodium Thiosulfate fix. It is just too weak!

    The top part of the image looks like fog. The bottom looks like underfixation.

    PE

  10. #10

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    PE, I have noted on other forums your suggestion re this....problem is I have no choice. I can't source Ammonium Thiosulphate in Sydney so I'm stuck with giving Sodium Thiosulfate a shot



 

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