Info on sodium sulfite and possible substitutions

Discussion in 'Darkroom Developing and Printing' started by Jopo75, Nov 7, 2003.

  1. Jopo75

    Jopo75 Guest

    I'm having a hard time finding sources for reasonably-priced stock of sodium
    sulfite (chemical reagent grade is way too much expensive, going about $ 25
    for 1kg).
    I want to home-brew some hca so I 've a 1kg sodium metabisulphite handy.
    Accounting the fact that the ratio sulphite:metabisulphite is 4:1 I must
    have 4kg of sodium sulphite to fully use the 1kg sodium metabisulphite!!

    What can I substitute sodium sulphite with?
    With potassium metabisulphite? Is this the same?
    Can plain sodium carbonate (soda) do the trick as well as homebrew hca?
    Thanks in advance.
    Jopo75, Nov 7, 2003
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  2. reasonably-priced stock of sodium
    Neither bisulfite, metabisulfite, or carbonate will do as
    a subsititute. Try places that sell supplies for home
    canning for sulfite, its used as a preservative and
    anti-oxidant in foods. Likely a Google search will turn up
    sources. You don't need reagent grade for photographic
    Richard Knoppow, Nov 7, 2003
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  3. Not the answer you were asking for, but why are you having such a hard time
    finding this more cheaply? Photographer's Formulary has it for about $5/lb:

    (This is the usual spelling, rather than "sulphite".)
    David Nebenzahl, Nov 7, 2003
  4. Jopo75

    Jopo75 Guest

    Because I live in Italy and ordering from U.s.a. the shipping cost would
    counterweight the convenience of homebrewing.
    But the soudium carbonate should act as a hca (Agfa recommend this).
    Jopo75, Nov 7, 2003
  5. I tried going this route, as I had discovered via Googling that s.sulfite is
    used for preserving foods. So I called a couple of local places (San Francisco
    East Bay area).

    Place # 1 had a guy telling me that I couldn't buy s.sulfite any more,
    basically, because all the environmental wackos in California had made
    everything so hard and over-regulated that he couldn't sell it; in fact, the
    guy tried to tell me that he couldn't even *advise* me on the use of this
    substance without running afoul of the law. (I assume he was referring to
    Proposition 65, which in fact does none of the dire things he was implying.
    But whatever.) I think the guy just couldn't be bothered to help me.

    Next call was to Cargill, Inc.; you know, the huge agro-conglomerate that
    operates the salt evaporators down in our South Bay. The guy there was much
    nicer, but his spiel was that because of post-9/11 regs (which he actually
    referred to as "bullshit"), they couldn't sell it because it was a potential
    component for explosives (?!?!?!). I think he had "sulfite" confused with
    "nitrate". He was surprised to find out that I could just go down to my local
    photo shop and buy this stuff, no ATF paperwork, no nuttin'. In any case, they
    only deal with basically railroad-car quantities anyhow.

    The amount of misinformation circulating in the wide world (not just the
    Internet) is simply stupendous.

    Both of these places were listed in the yellow pages under "canning", by the way.

    So I guess it's back to the store, which sells a pound of the stuff for a
    little more than $6. More than you'd pay over the Web, but hey, I like the
    store and like to support it anyhow. Still cheaper than Kodak HCA.
    David Nebenzahl, Nov 7, 2003
  6. Jopo75

    Jorge Omar Guest

    It's a funny world.
    I drive 10 min to (one of) the local chemist, and come back home with 1Kg
    sulfite for about US$ 1.5...
    But to buy some metol, I would have to pay US$ 60 for 100g. Phenidone

    Jorge Omar, Nov 7, 2003
  7. Jopo75

    Jopo75 Guest

    Thanks anyway.
    Sodium sulfite is listed as 25 or 50kg packaging infact.
    That's too much for me.
    Jopo75, Nov 7, 2003
  8. Jopo75

    Jopo75 Guest

    I've calculated that, even with reagent-grade sodium sulfite, the cost of
    homebrewing my hca would be half of the cost of Kodak-packaged Hca.
    Jopo75, Nov 7, 2003
  9. Can I mail you some metol?


    Dennis O'Connor, Nov 7, 2003
  10. Jopo75

    Nick Zentena Guest

    Buying 1kg is always going to cost alot. But $25 is goofy.

    With the posting I'm going to suggest trying somebody like this:

    Drop them an email whatever and ask. They list photographic sodium sulfite
    on the site. Worse they say no. Maybe they ask you to buy a 50kg bag. Best
    they point you to somebody that can provide the product at a reasonable

    Good luck.

    Nick Zentena, Nov 7, 2003
  11. Jopo75

    Jorge Omar Guest

    Thanks, Denny, but at this time I'm doing fine with phenidone. The
    chemist has 400g in stock and I'm one of the very few users...

    Jorge Omar, Nov 7, 2003
  12. Jopo75

    brook Guest

    I found a local( to me) supplier that specializes in commerical
    swimming pool chemicals that sells 50lb bags for around 75$US, best
    price on hypo and sodium carbonate as well! let your fingers do the
    brook, Nov 7, 2003
  13. Jopo75

    Nick Zentena Guest

    Sodium sulfite gets used in many things so it makes sense to buy a good
    bit. You'll save money and it won't go to waste.

    Nick Zentena, Nov 8, 2003
  14. Jopo75

    Dan Quinn Guest

    Although I've not tested it, you should be able to make sodium
    sulfite from your metabisulite and sodium carbonate.
    If my equation is correct it should work. I will calculate the
    ratios and let you know. Dan
    Dan Quinn, Nov 8, 2003
  15. Carbonate really does not act the same way sulfite does.
    The Afga recommendation is based on 1930's technology.
    Carbonate will speed washing where the fixing bath
    contains aluminum sulfate (alum) as the hardener. It does
    nothing for unhardened emulsion, the paper support of fiber
    paper, or film fixed in chrome alum fixer.
    Aluminum sulfate hardener has a specific binding
    (mordanting) action on thiosulfate and on fixer reaction
    products over a fairly narrow range of pH. If the pH is made
    more alkaline the binding action no longer takes place.
    Carbonate increases the pH to way beyond this point. It
    eliminats the binding action but also undoes the hardening.
    Sulfite, OTOH, acts both to adjust the pH and as an ion
    exchange medium. The sulfite actually displaces thiosulfate
    and fixer reaction products. Since it is a mild halide
    solvent it also acts to remove some insoluble fixer reaction
    products from the emulsion. The ion exchange works in the
    paper support of fiber prints as well as the emulsion.
    Kodak Hypo Clearing Agent as a working solution, is about
    a 2% solution of sodium sulfite but it is also buffered to
    neutral pH. At pH 7 the mordanting action of alum hardener
    is eliminated but most of the hardening action is retained.
    Neutral pH also minimises emulsion swelling and thus the
    length of the diffusion path ions must follow to be washed
    out. KHCA also contains two sequestering agents (sodium
    citrate and EDTA tetrasodium salt) to eliminate a problem
    with depostion of insoluble salts from the water its mixed
    with. These sequestering agents are needed mainly when the
    solution is re-used.
    I am very surprized at how hard Sulfite seems to be to
    obtain. As pointed out by others here it is NOT used in
    making explosives and is a very common chemical in all sorts
    of places.
    Richard Knoppow, Nov 8, 2003
  16. Jopo75

    Jorge Omar Guest


    AFAIK, he can get metabissulfite.
    As it has been suggested above, what do you think of metabissulfite with
    some carbonate so solution is neutral or slightly alkali?

    Jorge Omar, Nov 8, 2003
  17. Sheesh; now that sounds like the kind of thing only a true chemistry geek
    would want to do. At this point, wouldn't it be cheaper, not to mention
    easier, just to go out and buy Kodak's (or Ilford's, or whoever's) HCA, rather
    than dicking around with mixing potions?
    David Nebenzahl, Nov 8, 2003
  18. Richard Knoppow, I have in my ignorance been using Kodak Rapid Fixer but
    because I use a water stop bath without acetic acid, I have chosen to not
    add the part B bottle with the sulfuric acid and alum to the fixer... Do you
    forsee any problems...
    Dennis O'Connor, Nov 8, 2003
  19. Your prints will all suddenly self-destruct. Very soon, I imagine.

    David "like the way the tape used to disappear in a cloud of smoke on 'Mission
    Impossible'" Nebenzahl
    David Nebenzahl, Nov 8, 2003
  20. Jopo75

    Jorge Omar Guest


    I'm not Richard, but I mix my own rapid fixer without the hardner part of
    the formula.
    Up to today I still have my negs. Dunno what may happen overnight (-:

    Jorge Omar, Nov 9, 2003
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