color developing Blix question

Discussion in 'Film and Processing' started by Donald Harpold, Aug 7, 2022.

  1. Hello
    I am getting ready to start color developing, (C41) and was wondering if the Blix will stain the sink or the plastic beakers.
  2. I would say, as a general rule, that any staining is a result of carried-over developer. In any case if you rinse it down the drain right away there probably won't be any staining. Provided there's no porous materials involved.

    FWIW, and I know you didn't ask this, "proper" C-41 uses separate bleach and fix. Historically, when combined, they don't play well together. (Blix IS fine for the PAPER process, though).
  3. The name "bleach" is a misnomer - the C-41, RA4, and E-6 bleach chief ingredient is EDTA (Ethylenediaminetetraacetic acid. It is a chelating agent, and not a bleach as you know bleaches to be. Modern color films and color photo papers are black & white emulsions. Laced in is incomplete dye. These are Cyan - Magenta - Yellow dye in an incomplete state called Leuco (Greek for white or colorless). The miracle of these materials is all three dyes are missing just one common ingredient present in the color developer. The color developer is black & white developer plus it contains the missing ingredient.

    As the developer works, it forms metallic silver brining up a black and white image. As the metallic silver forms oxygen dissolved in the waters of the developer tarnish
    the silver as it emerges. This is the catalyst that unites the missing ingredient, now the dyes blossom and a color picture is superimposed with the black & white image.

    The black & white image veils the color images. The bleach solution attacks the silver and chemically changes it to a salt of silver. Siver salts are solvable in fixer and are dissolved away. Now the color images become vivid.

    EDTA is used in foods and medicines. It won't stain your sink. Some people are allergic and thus in danger of getting a skin rash.

    EDTA is used to rid the human body of heavy metal poisons - it is a valuable medicine. Photo color processes once used potassium ferricyanide as the bleaching agent. It works better than EDTA but the name spells trouble even though it is not toxic. EDTA replaced years ago.

    The combined bleach - fix is inferior to separated bleach bath followed by a fix bath. However, use of the combined blix is a common practice for convenance..
    Last edited: Aug 8, 2022
  4. Hello
    Thanks for the info, I have the Cinestill C41 kit, is there a kit that has the separate bleach and fix?
    Thanks agaain
  5. @alan_marcus|2
    I always enjoy your detailed and informed posts. Thanks!

    stuart_pratt likes this.
  6. EDTA is a chelating agent, but ferric EDTA is iron already chelated.

    More important, ferric EDTA is an oxidizing agent.

    The other bleach sometimes used, more common in earlier years,
    is a ferricyanide. While cyanide sounds bad, the reason it is bad is that
    it can grab onto iron very strongly. It is, in fact, hard to get apart.

    Not much to worry about as far as plastics, but as its job is to
    oxidize silver, it can also oxidize other metals.

    I do remember 40 years ago doing E6 in the student darkroom
    at school, and noticing how bright and shiny the brass drain got
    when it went down. I put in plenty of water to dilute it, and flush
    it away. We had sinks like the usual chemistry lab sink, so with
    a thick brass drain not thin chrome plated like home sinks.

    I have had plastic bottles get stained with silver.
    Blix would probably fix that, but I haven't done it yet.

    Passivated stainless steel is supposed to be fine.
    Cheap versions, though, might not be.
  7. Hello
    Thanks again for all the info.
    I did pick up a Bellini kit from Freestyle that has the separate bleach and fixer, a little pricey but if better results should be worth it.
  8. If you want to make the Bleach --

    Ammonium Ferric EDTA solution (50 - 60%) 200 ml
    Ammonium Bromide 150 g
    Disodium EDTA 10 g
    Ammonium Sulfite 10 g
    Dissolve in 500 ml water
    Using acetic acid -- adjust the pH to 6.5

    How it works -- The developer reduces exposed silver salts (silver + halogen which is bromine or iodine or chlorine). The reduced halogen goes into solution (waters of the developer). Opaque silver makes up the black & white image. The bleach attacks the silver returning it to silver + bromine. The fixer follows and dissolves away the silver salt. Now the dyes show in all their glory.

    Halogen is Swedish for salt maker. In photo we use only three halogens Iodine lowest ISO films -- Chlorine next highest ISO -- Bromine highest ISO. Films and papers can be blends of different Halogens.
    Last edited: Aug 9, 2022
    NHSN likes this.
  9. And a small amount of iodide to make T-grain films.

    AgCl and AgBr crystallize in a cubic (FCC) lattice, while AgI is hexagonal.

    A small amount of AgI in the AgBr crystal stabilizes the hexagonal form.
  10. Greek, i think you meant to say.
    Last edited: Aug 10, 2022
  11. Just reading this online ...

    "In 1826, Swedish chemist Jons Berzelius coined the term halogen for the entire group of elements. The Greek word “hal”, meaning salt, also appears in the name of the mineral halite, aka sodium chloride. Properties of the Halogens …"

    Link - Halogens - Periodic Table | ChemTalk
    Last edited: Aug 10, 2022
  12. Blix will etch metals. So not good for stainless steel - tanks or sinks. And conversely a stainless developing tank and reel aren't good for blix.

    It'll work, but you'll get a shorter working life from the bleach-fix, and eventually your tank and reels will get an etched look.

    If you're going to tip the blix down a domestic SS sink, run the cold tap first to immediately dilute it before it hits the metal.
  13. I believe stainless steel film tanks and reels are designed for it.

    But household stainless bowls might not be.

    I had a stainless steel bowl that I was using in the darkroom, and never poured
    full strength blix or bleach into it. Maybe just rinse water. But then it got a hole.

    We also had a kitchen counter compost bin that was stainless steel, that got a
    hole from ordinary kitchen chemistry.

    The instructions for the Nikor tanks mention passivating them with nitric acid.

    I never had a problem with actual Nikor tanks. Cheaper ones might not be so good.
  14. Well, I noticed my SS tank and reels getting a dulled and etched look after just a few C41 process runs. After that I switched to plastic Jobo tank/reels in a CPE-2 processor - but I would have switched anyway after buying the CPE-2. Its tempering bath and automated agitation make things much more reliable and consistent.
  15. I still have the 35mm Nikor tank that I inherited from my grandfather when I was 10,
    and that is the one I had when I did E6 and C41. I now have more tanks,
    some of which were given to me by people who aren't doing darkroom
    work anymore. As well as I remember, they are all still shiny.

    I also have a Nikor 116 tank, which I haven't used for C41 yet, but maybe.
    (I have some rolls of C116.)

    But yes, an automatic tempering bath would be nice.

    I did E6 and C41 with the tank in a tray full of water at the right
    temperature, and tried to keep it at that temperature.

    The 116 tank was likely not so used, and still has the instruction sheet.
    (Unlike my other tanks.) That is the one that says to use nitric acid
    to passivate the stainless steel. Not that I have any around.

    As my grandfather told me 50 years ago, it takes a little while to get
    used to loading Nikor reels, but once you get used to them, they are
    easier and faster. And that is how I remember it.
  16. Well, 316 stainless is considered satisfactory for anything in the C-41 process (see the Z-131 manual for confirmation). Large commercial machines typically have 316 SS tanks and metal rack parts, etc. (Note that ferricyanide bleaches, not part of C-41, are an exception to this).

    But, to what I think is your point, general-use SS is most likely not 316.

    More information can be found in the SPSE Handbook of Photographic Science and Engineering; see the chapter on materials of construction.

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