RA4 STOP BATH QUESTION

Discussion in 'Color: Film, Paper, and Chemistry' started by David Lyga, Apr 20, 2011.

  1. David Lyga

    David Lyga Subscriber

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    Can a regular acetic stop bath ever be sufficient, given that it is changed frequently?
    Why is sodium sulfite recommended to be added to the acetic bath? Doesn't the acid and water, alone, remove the developer efficiently.

    I do something rather unorthodox: after the stop bath I fix and turn lights on to view the print. Sometimes I let it go at that. Sometimes I do want the slight increase in warmth so I will then, in full light, bleach (potassium ferricyanide) for a minute, and then for a few seconds, I fix again in the same fixer. I think that that is a much more rational way to go about this process. I do the same fix/bleach reversal with film. Why does everybody else bleach before fixation?

    Another question (will reflect my chemical naivity) : if one bleaches (color paper or film) in full roomlight is there a danger of (is it called) halogenation with the silver salts being made sensitive to light? Thanks for all the information you are able to impart. - David Lyga.
     
  2. Photo Engineer

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    I use 1% to 2% Acetic Acid as the stop bath for RA4. I have also used Kodak Indicator Stop. Both work just fine.

    If you leave out the Sulfite from the Acetic Acid, then the Stop becomes an indicator bath turning cherry red when it becomes exhausted. Adding Sulfite will NOT regenerate it but will decolorize it thereby giving you no notice of exhaustion.

    If you bleach in most Ferri bleaches, you rehalogenize the Silver as it oxidizes and this Silver salt is light sensitive. As for using a fix, it depends on the fix. The fix baths used for color processes are selected to prevent shifts in dye hue due to pH. Also, just fixing makes a print darker and less saturated and therefore harder to evaluate.

    PE
     
  3. David Lyga

    David Lyga Subscriber

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    Thank you PE. Letting it go at simply fixation does give a rather subdued color (even Hollywood did this a few times with their films). Some scenes might benefit. It is a bit darker but you can always expose a bit less. You do scare me when you confirm that the silver, once again, begins to be light sensitive. Does that mean potential light fog? Is it best to bleach in darkness and fix again before turning on the lights? As you can see my chemisty knowedge is competition for MIT. - David Lyga
     
  4. hpulley

    hpulley Member

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    So that's why my stop bath turned cherry red, thanks! I knew to chuck it out anyways but did wonder!!!

    I do my RA-4 in full darkness until it is fully fixed. Haven't dared to try my amber safelight yet.
     
  5. Photo Engineer

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    If you fix and do not bleach, there is nothing light sensitive present, but if you bleach with no following fix, there are light sensitive materials that can darken. If you fix, bleach and then wash and dry, you still have light sensitive materials present. This is only if you use a Ferri bleach.

    I use 2 safelights all the time. One pointed at the ceiling and one pointed away from the enlarger and both at about 5 feet. No fog ever!

    PE
     
  6. hpulley

    hpulley Member

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    OK, I'll have to try it. What is there to lose but a sheet of paper I guess though the fact sheets all seem to say complete darkness is best or it will fog.
     
  7. brucemuir

    brucemuir Member

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    I use a color safe light occasionally.
    I cant notice fog.
     
  8. Photo Engineer

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    Kodak paper is built to allow a WR-13 series safelight.

    PE
     
  9. brucemuir

    brucemuir Member

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    here's the quote from the Portra/Supra tech pub:

    Using a safelight will affect your results. If absolutely
    necessary, you can use a safelight equipped with a KODAK
    13 Safelight Filter (amber) with a 7 1/2-watt bulb. Keep the
    safelight at least 1.2 metres (4 feet) from the paper. Keep
    safelight exposure as short as possible. Run tests to
    determine that safelight use gives acceptable results for
    your application
     
  10. hpulley

    hpulley Member

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    That's what sent me scurrying into the dark... and actually I found it wasn't that hard to do really. I only messed up one page before learning how to ensure the paper is fully in the tray and covered by liquid.
     
  11. brucemuir

    brucemuir Member

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    I learned in the dark but getting the paper in the easel takes some doing.

    wonder what they mean by
    "will effect your results"

    they dont go as far as saying the word fog
     
  12. Photo Engineer

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    Gentlemen;

    You are speaking one of the guys who used to sensitize and coat color paper. I selected the Magenta (green sensitive) layer dye and AFAIK, it is still used. I have used Endura, Supra, Plus and 30/37 under WR-13 safelights since the 60s and earlier before I went to Kodak. The current dyes are even more "safe".

    I used to teach color printing at Kodak Park and we used safelights there as well.

    I assure you that those guidelines above are safe and even quite conservative. Just test first.

    PE
     
  13. Roger Cole

    Roger Cole Member

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    I have an old Osram Duka 50 sodium safelight I used to use all the time with RA4 and even Ilfochrome and Kodak Type R paper (which always insisted on no safelight) and never had a problem or detectable fog. I used the lowest setting and bounced it off my white ceiling, but it was bright enough to make out the outlines of everything in the darkroom and that was a big help. I still have it but once it burns out I'll have to get something else. I have a Jobo Maxilux LED that was supposed to be safe for color but haven't tried it, and it doesn't seem it will be nearly as bright as the (already dim, used that way) Duka 50.

    But with an appropriate safelight it's definitely possible - or was, and I'm pleased to learn that today's very fast papers aren't any less safe with a proper safelight.
     
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  15. hrst

    hrst Member

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    I find that safelight is most useful when I need to move the paper from developer to stop. Naturally, at this point, I can use high enough level of illumination to comfortably fish the paper from the developer tray. The level I use at this point causes some minor fogging after 30 seconds if used before developer, but when used when the developer time is up, the paper receives only less than 15 seconds of development after the exposure.

    "General" illumination has to be very low level, still better than nothing; but if used only "when you need it" and "where you need it", the level can be substantial; test it first.

    I use general yellow LEDs as is. Proper Wratten 13 filter added would probably allow me to double the illumination level.
     
  16. darkroom_rookie

    darkroom_rookie Member

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    I also use two safelights for RA-4 with #13 Kodak filters. One is near the ceiling and pointing at it, more than 7 ft away and the other can be mounted to point at the ceiling as well as away from it, at the paper, at about 5-6 ft. This is to facilitate making color photograms. Not a single cause of fog with either Supra III, Supra Endura or Ultra Endura when enlarging negatives, with the paper being exposed to safelights no more than 2 minutes total, as it's processed in drums. Photograms so far all seem to have pretty good whites that don't seem fogged, but, of course, YMMV.
     
  17. hpulley

    hpulley Member

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    What about while cutting down long rolls?
     
  18. pentaxuser

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    I have been using APUG for a few years now and this business of RA4 and the need for total darkness seem to be one of the hardest myths to kill.

    My experience like Roger Cole's is that if you want a reasonable non fogging light level then the DUKA sodium light is the way to go. Yes it will give enough light to allow you to cut sheets - at least in my experience.

    pentaxuser
     
  19. hpulley

    hpulley Member

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    OK, I ordered a Kodak #13 safelight 5x7 insert and 7.5 watt bulb for my lamp. In the meantime should I continue to work in the dark or should I even try my Ilford 902 with 15 watt bulb? I guess at most I fog a page trying...
     
  20. Greg Davis

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    Use Kodak's K-4 publication to test your safelight. It will show you how long you can have both exposed, and unexposed paper out before fogging occurs.
     
  21. hrst

    hrst Member

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    Typical B&W yellow light won't probably work, or you have to keep the level so low you cannot practically use it. They will contain red wavelenghts. Color safelight has a very narrow band just between the red and green, hitting the sensitivity minimum valley. B&W yellow light MIGHT be good for green layer (cannot be guaranteed) but still not good for red layers, creating either blue or cyan fog.
     
  22. hpulley

    hpulley Member

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    Tried my B&W safelight today, terrible cyan fog so went back to working in the dark until my Kodak #13 arrives. Will see if I can find 7.5 watt bulb too, current one is 15w.
     
  23. Greg Davis

    Greg Davis Member

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    The OC filter for B&W will definitely not work. Be aware that the #13 is much darker than the OC filter, so the illumination level will be very low.
     
  24. hpulley

    hpulley Member

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    I'm used to working in the dark for color printing (how my Dad showed me decades ago) so any illumination at all will be nice. I wasted some Fuji CA this morning because I had the paper upside down :sad: it is thin but not THAT thin :laugh:
     
  25. Greg Davis

    Greg Davis Member

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    I, too, learned to print color in the dark. Once I tried a Thomas Duplex with the color filters in it, though, I have never gone back.
     
  26. Photo Engineer

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    I have never really done color printing in total darkness as far as I can remember. I have always used a Kodak safelight of some sort or another. Currently it is the WR13, but there was a predecessor for the original Type C paper that was brighter due to the slower paper speed at that time.

    PE