Sodium Metabisulfite vs Sodium Sulfite

Discussion in 'B&W: Film, Paper, Chemistry' started by kb3lms, Dec 5, 2012.

  1. kb3lms

    kb3lms Subscriber

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    My supply of sodium sulfite is running low. I have a 5 pound bag of Sodium Metabisulfite. Any way I can convert the metabisulfite for use before I order more sulfite? Is it worth doing?

    Thanks!
     
  2. luizjorgemn

    luizjorgemn Member

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    I was on the other side of the rope, figuring out how to replace metabisulfite on a formula and the only possible substitution was sodium bisulfite. I guess you shoul order sodium sulfide right now...


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  3. kb3lms

    kb3lms Subscriber

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    Lol, I guess so. Well, thought it was worth asking since IDK what to do with this metabisulfite. Maybe it will be good for the roses?

    -- Jason
     
  4. Gerald C Koch

    Gerald C Koch Member

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    Sodium metabisulfite can be used in the making of acidic fixers. stop bath, washing aid, and divided developers.
     
  5. Rudeofus

    Rudeofus Subscriber

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    Sodium Metabisulfite is a dehydrated form of Sodium Bisulfite: 2 NaHSO3 <----> Na2S2O5 + H2O

    If you dissolve them in water, they will be the same. In aqueous solution you can convert the Sodium Metabisulfite to Sodium Sulfite by adding 2 moles of NaOH per mole of Na2S2O5.
     
  6. Ian Grant

    Ian Grant Subscriber

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    This is how the Sulphite is made in a concentrated form in Rodinal manufacture.

    Ian
     
  7. Gerald C Koch

    Gerald C Koch Member

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    What looks very simple on paper will be a mess when you are dealing with pound quantities of this chemical. A lot of heat will br given off and the solution may splatter when the hydroxide is added. Sodium sulfite is not that expensive. Besides you have to pay for the sodium hydroxide.
     
  8. Rudeofus

    Rudeofus Subscriber

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    Let's all agree that mixing Sodium Metabisulfite and Sodium Hydroxide is an expensive and inconvenient substitute for Sodium Sulfite, but once you've run out you are at the mercy of whoever supplies you and this can take a few days if not more.

    Most developer recipes require substantially less than "pound quantities", therefore my substitute suggestion, with all its limitations as stated above, might work quite well for kb3lms. Depending on target pH and availability of pH metering device he might even get away with Sodium Metabisulfite and Sodium Carbonate in case he only has these.
     
  9. Ian Grant

    Ian Grant Subscriber

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    It's one of the commercial ways Sodium Sulphite is manufactured, so it's a logical but less practical option. On a larger scale it's cheaper.

    Ian
     
  10. Rudeofus

    Rudeofus Subscriber

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    Let's all agree that those who make Sodium Sulfite commercially usually don't resort to APUG for instructions ... :cool:
     
  11. Ian Grant

    Ian Grant Subscriber

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    And your point is ?

    On a smaller scale it's still an easy way to make concentrated Sulphite solutions, and to overcome Geralds comments about heat and spalttering you carry out the addition of the hydroxide slowly.

    It's not rocket science and quite similar to making your own Sodium Metaborate (Kodalk) from Borax and Sodium Hydroxide which was quite normal outside the US where Metaborate was always harder to get hold of.

    Ian
     
  12. luizjorgemn

    luizjorgemn Member

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    We don't have kodalk here in Brazil. Thanks for this!


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  13. Rudeofus

    Rudeofus Subscriber

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    Look at Mike Wilde's precious posting for instructions on how to replace Kodalk with Borax and Sodium Hydroxide.
     
  14. kb3lms

    kb3lms Subscriber

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    You can go through sulfite pretty fast mixing developers to try different ones. Anyway, I don't have a problem buying sulfite, just have this 5 pound bag of the metabisulfite that I'd like to use up. NaOH I have as well so using a bit to convert the MBS in small quantities might be doable. Till it gets used for some other things as well, that ought to take care of it. Thanks!
     
  15. luizjorgemn

    luizjorgemn Member

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    Really precious adice. Thanks very much!!!


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  16. c6h6o3

    c6h6o3 Member

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  17. Rudeofus

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    Jim, a chemical that you have sitting around unused and with no future purpose is basically free. That's hard to beat!
     
  18. pdeeh

    pdeeh Member

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    I wonder if those in the US realise how relatively easy and inexpensive it seems to be to obtain raw chemicals there.
    Much more difficult in the UK, can't speak for the rest of Europe
    examples: Sulfite comes in at about $6 /500g, while I've just seen Metaborate at $45 /500g from one of our (few) photographic chemistry suppliers.
     
  19. c6h6o3

    c6h6o3 Member

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    It's far from free when you factor in the time, trouble and perhaps other chemicals needed to convert it. And the OP lives in the US. Converting sodium metabisulfite to sodium sulfite rather than buying some is what I would have to call "penny wise and pound foolish".
     
  20. Gerald C Koch

    Gerald C Koch Member

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    It's only free if you think that your time and effort isn't worth anything.
     
  21. Rudeofus

    Rudeofus Subscriber

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    Xtol mops the floor with 99% of the home brew developer recipes that keep getting posted here over and over again. If it comes with free learning, it might still be worth the extra time and effort, and maybe some folks actually enjoy playing with photo chemistry in their leisure time.

    BTW nowhere did I read that kb3lms plans on never buying Sulfite ever again.
     
  22. luizjorgemn

    luizjorgemn Member

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    In Brazil we have all sorts of dificulties to buy raw chemicals. As a doctor I can buy some using my business (i own a private clinic) as an excuse, and I buy for some friends. The prices aren't so good but are affordable. I can't find some items like phenidone, glycin and chemicals for E6.
    The prices here (converted to dollars): sodium sulfite $1.40 1kg, metol $50 100g, hidroquinone $30 500g, borax $10 1kg... much cheaper than buy d76 from kodak


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