Mixing Pextral's Two Bath; Substitute for Sodium Hydroxide?

Discussion in 'B&W: Film, Paper, Chemistry' started by Justin Low, Jun 24, 2007.

  1. Justin Low

    Justin Low Member

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    Hi!

    I plan to mix up a batch of Pextral's Two Bath developer as detailed in the recipes section.

    The recipe calls for sodium hydroxide in the second bath (1% solution), presumably as an accelerator. The job is done in "seconds", so I'm guessing that a lesser base would still be effective.

    For reasons of health and safety, would there be any substituting NaOH for say potassium carbonate or sodium carbonate? What ratios should I use?

    Thanks!

    Justin
     
  2. dancqu

    dancqu Member

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    TSP, trisodium phosphate will likely make a good
    substitute. A ph only a little short of lye. Dan
     
  3. Ole

    Ole Moderator Staff Member Moderator

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    Carbonates could be worth trying, too. It's not the concentration that's important, it's more the pH. Using a lower pH second bath will change the characteristics, but could well give good results.
     
  4. Justin Low

    Justin Low Member

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    Thanks Dan, and Ole. I will see if I can find TSP at the hardware store, but in the meantime, I'll mix up some sodium carbonate and see if that works well enough.
     
  5. Alan Johnson

    Alan Johnson Subscriber

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  6. Justin Low

    Justin Low Member

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    Alan, that's a godsend. A 10% solution should be a good starting point then. Thanks!
     
  7. gainer

    gainer Subscriber

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    Slaked lime from the garden shop + sodium carbonate from the swimming pool shop + water from the sky makes a solution of sodium hydroxide with precipitated calcium carbonate. It is left as an excercise for the student to calculate the amounts of lime, soda ash and water to make a 1% solution in sufficient quantity that you can get the amount of 1% solution you want by siphoning it off, leaving the precipitated limestone. It won't hurt, of course, if you make more than you need.
     
  8. gainer

    gainer Subscriber

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    1 molecular weight of calcium hydroxide + 1 molecular weight of sodium carbonate produce 2 molecular weights of sodium hydroxide and 1 molecular weight of calcium carbonate. 1 molecular weight of sodium hydroxide is 40 grams. 40 grams in 400 ml of solution is a 10% solution.
     
  9. z-man

    z-man Member

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    sodium hydroxide susitute????

    "ultra bleach" on the shelf in the supermarket lists active ingrediants:
    sodium hypochlorite, sodium hydroxide

    what do you think????

    hey gainer-can't find my way back to site where your aticles on vit c dev most especially using anti freeze to make non oxidising shelf solutions

    can't use pdfs so i need to read on site-can you direct me?

    thanx

    vaya con dios
     
  10. z-man

    z-man Member

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    just remembered-store brand cheapo "ultra bleach" only active ingrediant: sodium hydroxide-it is close to 1% i think

    why mix when you can buy off the shelf???
     
  11. Ole

    Ole Moderator Staff Member Moderator

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    I think it's a very bad idea to soak film in anything containing sodium hypochlorite.

    A developer is a mild reducing agent, sodium hypochlorite is a strong oxidising agent. Mixing the two are a very quick and efficient way of destroying your developer.

    In a two-bath process, most of the developer absorbed in the emulsion would be oxidised by the hypochlorite before the high pH could activate it. Any developed silver would then be bleached away by the hypochlorite...
     
  12. Justin Low

    Justin Low Member

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    I mixed up a 1% solution of catechol, and a 10% solution of sodium carbonate this evening, and just ran a short roll through it. The exposures look good to my eye, and I'm surprised that APX400S stained so well; even better, the emulsion doesn't feel slimy (unlike when I use Rodinal, perhaps this is due to the hardening action of catechol?).

    I'll scan the film when it dries, and have some samples up. Thanks guys!
     
  13. Justin Low

    Justin Low Member

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    I've posted some scans to my Flickr account: http://www.flickr.com/photos/justinlow/sets/72157600480517956/

    My impressions are that the pictures are rather grainy, on par with Rodinal. The tones look nice but the acid test would be in the printing. I'm amazed that something so simple can work so well.

    I read in the recipe that sodium sulfite may be added to adjust the graininess of the results. Would I be right to say that a small addition would reduce the appearance of the grain?

    Thanks!
     
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  15. juan

    juan Subscriber

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    Cachetol and carbonate were the basis for Jay DeFehr's Hypercat developer. He made a lot of claims for it - other folks didn't buy his claims. I tried it for a short time, and it worked and showed promise. I just didn't have time to master it.
    juan
     
  16. srs5694

    srs5694 Member

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  17. Tom Hoskinson

    Tom Hoskinson Member

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    Try it - but if you add very much sodium sulfite, it will decrease and/or eliminate the stain and the tanning effect.

    Also, you might try one of Pat Gainer's procedures and add a few grams of ascorbic acid - instead of the sulfite.
     
  18. z-man

    z-man Member

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    gainer articles

    srs-muchisma gracias

    the unblinkingeye link was what i needed

    ole-it was not my intention to dump bleach in the developer-just that if you need sodium hydroxide and it is allready waiting for you on the shelf in the supermkt, re cheapo house brand "ultra bleach" -active ingrdnt sodium hydroxide @ approx 1% and if it is needed for the mix why not try that instead of diluiting down draino? but thanks for the heads up-i'm chemically challenged and dislexic so i need to be reeled in at times

    vaya con dios
     
  19. Justin Low

    Justin Low Member

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    Thanks for the suggestion Tom. I have some ascorbic acid handy, and will try it. However, would that not reduce the shelf life of the catechol solution?

    Justin
     
  20. Murray Kelly

    Murray Kelly Member

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    Painters Sugar Soap in Oz is a mix of carbonate and TSP AFAIK.
    I have used some as a second bath for Thornton's 2-bath OK.
    Murray
     
  21. Justin Low

    Justin Low Member

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    Would the sodium carbonate bath be reusable, or is it one-shot?
     
  22. gainer

    gainer Subscriber

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    I keep hypochlorite far from film unless I want to remove the emulsion for some reason, such as to measure base density. If you want to see the extreme, dunk a piece of junk film in chlorine bleach. Very dilute hypochlorite may be no worse than some chlorinated water from some public water supplies, but I don't like that either.
     
  23. Tom Hoskinson

    Tom Hoskinson Member

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    Possibly, but that won't matter much if you are using this developer as a ONE-SHOT.
     
  24. gainer

    gainer Subscriber

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    If you want to add ascorbic acid without changing the acidity of the solution, mix it with baking soda in a little water and wait for the effervescence to subside before adding it to the solution. 1 level teaspoon ascorbic acid plus 1/2 level teaspoon of baking soda (sodium bicarbonate) in a couple of ounces of water gives the equivalent of 4 grams of ascorbic acid at near neutral pH.
     
  25. gainer

    gainer Subscriber

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    I forgot to mention that the added ascorbate will not reduce the shelf life of the catechol.
     
  26. Murray Kelly

    Murray Kelly Member

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    In a 2-bath the carbonate is reusable.
    Murray