Stop Bath Substitutes

Discussion in 'B&W: Film, Paper, Chemistry' started by jimgalli, Feb 5, 2009.

  1. jimgalli

    jimgalli Subscriber

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    I've run out of ordinary stop bath, and no, I don't have any vinegar in the cupboard. I do have a bunch of part B sulfuric acid hardener left over from Rapid Fix I never used. How would that work as a stop? This is for RC prints.
     
  2. 2F/2F

    2F/2F Member

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    For RC prints, I would feel totally comfortable just using a post-development rinse in a tray of tap water before fixing. Going straight into the fixer would stop the development post haste, but rinsing first would lower the amount of developer carryover into the fixer.
     
  3. Photo Engineer

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    If you use just a tray of still water as a stop, then go into a neutral or alkaline fix, you run the risk of fogging your paper or getting incomplete fixation. Also, if you use a metol developer, the metol will not be totally removed in this type of process.

    If you use water, it should be running water, and if the fix is neutral or alkaline, leave the lights out (safelight on) for the full fixation time.

    PE
     
  4. OP
    OP
    jimgalli

    jimgalli Subscriber

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    Dektol and Rapid fix. So no Surlfuric acid fix then, tap water is best. That's what I'm doing as we speak. Thanks!
     
  5. ronlamarsh

    ronlamarsh Member

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    stop bath

    I find the comments here very interesting. I am presently using TF-4 archival rapid fix from Photographers formulary and their literature suggests a "running water" stop for 2 min and cautions that the use of an acid stop causes the fixer to deplete more rapidly. Makes sense I guess. I usually put the print into a tray of still water and then use my hand sprayer to gently wash the print at the same time.
    Would like to know from Photoengineer if this would be adequte to remove the metol from the developer. I haven't as yet noticed any fogging problems.
     
  6. jim appleyard

    jim appleyard Member

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    I've been doing a metol print dev (dektol), water stop (not running, but changed often) and TF-3 fix for RC paper for years. Fix for 2 min., first min with safelight on, 2nd minute with room lights. I haven't noticed anything. In fact, this is the first I've heard of this. I would also be interested in learning more.
     
  7. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    In my tankline which starts with Acufine and ends with TF-4, I used water for a while, but since I was getting very short development times in the summer, I decided to add a 10% solution of sodium metabisulfite as a stop, which is one of the formulas in Anchell and Troop, and it seems to be working, and despite the acidity, hasn't caused an unexpected fixer crash.
     
  8. tiberiustibz

    tiberiustibz Member

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    I've used vinegar before.
     
  9. Bruce Osgood

    Bruce Osgood Membership Council Council

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    I've stoped using a chemical stop bath. In its' place i use a tray of water for one minute and a hose rinse before TF3 or 4 fixing. No hypo.
     
  10. Photo Engineer

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    Metol is an alkaline organic compound that is delivered to us as a sulfuric acid salt in powder form. When you place it in developer it is hard to dissolve in alkali whereas HQ is easy to dissolve as it is an organic acid.

    In the acid stop, Metol dissolves happily, and in the TF-4 the HQ dissolves happily giving you the best of both worlds. TF-4 is so well buffered, it is able to survive the use of a stop bath. I have tested that and it works due to the high buffer capacity of the fix. Even if the pH drops, the fix still works. All you need is about 2x longer wash if the pH of the TF-4 drops below about 7.0.

    PE
     
  11. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I think when I've measured fresh TF-4 it has a pH of about 8.0.

    If it drops to 7.0, would you recommend adding, say, sodium hydroxide to keep the pH up to 8.0, for the purpose of maintaining a shorter wash time?
     
  12. Photo Engineer

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    Sodium Hydroxide would do nicely. You could use carbonate as well or Kodalk. It would just take more of them. Kodalk would be better than carbonate.

    Never ever add potassium salts to fixers.
     
  13. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Thanks for the advice.
     
  14. Bruce Osgood

    Bruce Osgood Membership Council Council

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  15. Photo Engineer

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    pH, as David noted. Add and measure pH using pH paper or a meter.

    If you cannot do this, don't try.

    PE
     
  16. jim appleyard

    jim appleyard Member

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    Have I been doing it wrong all these years? I don't have a pH meter, just Edwal Hypo Check which probably doesn't account for pH. I never bothered to check for pH. I could add Kodalk, but how much and when?
     
  17. Bill Harrison

    Bill Harrison Subscriber

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    ph measurement?

    I often see refs to ph measurement as photoeng. did in the last post. What is a preferred way to accurately measure ph? Indicator paper was used in HS chem class but hardly accurate as I remember.... Is there a meter? Also is there a way to measure water hardness without the cost of sending out a sample to a lab? Two things I've often wondered about, so thought I'd jump all over this opportunity..... Thanks, Bill
     
  18. Thomas Bertilsson

    Thomas Bertilsson Member

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    When using liquid emulsion from Rockland, they recommend using a VERY dilute fixer as a stop bath (because the acidity of a normal stop bath will potentially harm the fragile emulsion, in their words). I forget the fixer/water ratio now. Perhaps that would be a good option? What say the experts? Can this be used for RC paper as well?
     
    Last edited by a moderator: Feb 6, 2009
  19. Bruce Osgood

    Bruce Osgood Membership Council Council

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  20. Photo Engineer

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    Today's pH strips measure in small increments with 3 color tabs that change color to give you pH. The HANA meter is excellent and can be purchased new from the Photographer's Formulary.

    Hypo check has no ability to measure pH whatsoever. It just tells you whether the fixer you have can still fix film or paper.

    Thinking it over, another way to make the TF-4 alkaline is to add some Ammonium Hydroxide. Unscented household ammonia is 3% and should do the job provided the pH is not too acidic. Otherwise you would dilute your fixer.

    PE
     
  21. dancqu

    dancqu Member

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    The Purpose of the Short Acid Stop.

    The short acid stops recommended by Kodak and Ilford,
    10 and 30 seconds respectively, are intended to convey
    an acidic character to the film or paper. Acidic so that
    the acidic fixers remain so. Although the developer in
    in the film or paper is reduced by the stop it's
    substantial reduction occurs in the fix.

    If the fix is alkaline there is no point in using an acid
    fix. A 30 second water rinse will do as well or better
    at rinsing out the developer than Ilford's 30 second
    acid stop.

    Why worry about some little developer, what ever
    it's composition, showing up in the fixer? After all there
    are still post fix washings ahead. If the fixer is acidic
    there should be no worry; note the very short acidic
    stops which precede. Not so with an alkaline fixer.
    The activity of any carried forward developer is
    maintained. As the fixer's silver load increases
    the chances of in solution reduction increases.
    Silver may deposit on any surface. Dan