RA Blix how to improve session longevity

Discussion in 'Color: Film, Paper, and Chemistry' started by markbarendt, Jun 20, 2010.

  1. markbarendt

    markbarendt Subscriber

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    I'm using the Kodak RA-4 chemicals in trays and the Blix seems to die about twice as fast as the developer during a session.

    I'm thinking that it may be developer carryover.

    It there any reason not to add a quick rinse (or maybe even a stop bath) between the developer and the Blix?
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    Kodak recommends a stop bath after the developer. This can be 1 - 2% acetic acid or normal Kodak Indicator Stop. I once thought that the dye might stain the paper, but was urged to try it and it works just fine.

    One way to regenerate it is to place it in a half full bottle, cap it, shake it and let it stand for a day. Then add 100 ml of fresh blix to every liter of this regenerated blix.

    PE
     
  3. steelneck

    steelneck Member

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    @PE: I have used citric acid as stop and from what i could tell it works just as well. Is there be any drawback to use citric acid instead of acetic? (the citric is odorless)
     
  4. markbarendt

    markbarendt Subscriber

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    You are a true gem PE!

    I have plenty of stop bath so that will become part of my process.

    I'll also start regenerating. I've actually been putting protective gas on top of the saved Blix between sessions, no more of that nonsense. :wink:
     
  5. Photo Engineer

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    Protective gas can be of some slight help with unused blix, but blix does spontaneously undergo decomposition. I (we) tried to make it very stable though and it does last a long time in 2 parts but less time as one part. The limitation is due to the Ammonium Hypo component. Any blix or blix component that becomes cloudy is bad. It may work, but may leave a mild unpleasant haze in your prints. This is due to Sulfur particles that may become trapped in the coating.

    As for Citric Acid, I was told not to use it for color. I have never tried nor have I seen proof one way or another. So, I cannot say. I stick with acetic acid as the odor does not bother me. I have used citric acid with B&W but do not regularly use it.

    I am always glad to be of help. I appreciate your comments.

    PE
     
  6. hrst

    hrst Member

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    During a session?? I find that the same blix is good for all my sessions for half a year! It might only be about 20-30 prints though as I don't print so much/often. I use stop.
     
  7. markbarendt

    markbarendt Subscriber

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    That makes me wonder if it might not be better if the bleach and fix were run as separate steps. :confused:
     
  8. frotog

    frotog Member

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    I run kodak ra-4 bleach fix with kodak bleach fix additive. I had to purchase a case of the stuff to get my distributer to order it for me. 15 ml of additive to 1 ltr. of blix. Works wonders in extending the life of the blix.
     
  9. markbarendt

    markbarendt Subscriber

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    That's interesting, I'm finding that the storage life is much better than I expected on both C-41 and RA-4 chemicals. Half a year is quite a lot longer than I would have expected, that's good.

    It was cute, I found some roll paper on Ebay cheap, ~600 feet of Crystal Archive for $40 shipped and ~600 feet of Ektacolor Edge for $25. Mini-lab guy in Tennessee had bought a bunch of it.

    With the deal done I told him I was fairly new to RA-4 printing and asked him if the shelf life would be a year or better. He indicated it would probably be just fine.

    His curiosity was peaked, "1200 feet in a year? :confused:" (The implication was that that was a pretty small number.)

    Then his magic question. "What type of machine are you using?

    He wasn't expecting me to say "Trays".
     
  10. steelneck

    steelneck Member

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    I wonder why you got that recommendation? Well i have used both citric and acetic stop for both film and paper, both BW and RA-4. I could not see any difference picture wise, but on the other hand i use the stop to extend the life of the next bath, not because i thought there would be any difference in the picture.

    I do not bother about the smell either, but my wife and son do - Does it have to smell like that? - is comments i have got. Especially from my son. I guess that is because my wife knows what it is and use it in kitchen, and my son associate the smell with things he do _not_ like to eat..
     
  11. brucemuir

    brucemuir Member

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    how can you tell when the blix is spent?

    do you prints fade when exposed to white light/washing?
     
  12. Photo Engineer

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    Regarding citric acid, it is very polar compared to acetic acid. In a color process it is essential to get acid into the coupler solvent drops to neutralize the color developer and extract it. Citric acid, I have been told, is less efficient at this due to polarity. I have never tested it so IDK. The result would be a pinkish stain and lower image stability.

    A spent blix would cause darker, contaminated colors and a gradual browning or yellowing of the print. The result is similar to using spent fix on B&W prints.

    PE
     
  13. markbarendt

    markbarendt Subscriber

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    Okay, so what causes a bluing, similar to a sheet that is just exposed to light just lighter?
     
  14. Photo Engineer

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    A spent blix retains silver metal as well and the silver metal combined with dye can cause a blue cast as well as dingy dark colors in general. It depends on the amount of retained silver.

    OTOH, insufficient development can also cause a blue cast as can improper optical brightner.

    PE
     
  15. markbarendt

    markbarendt Subscriber

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    Thanks PE

    I found part of my issue tonight, I have been inadvertently bumping my hot plate thermostat.

    Tonight I started getting a brownish cast on the third sheet, checked the temp and I was up from 90 to 100.

    I shortened my develop and blix times from 1:10 to 90 sec and the problem was gone. Ran at 100 the rest of the evening sweet as pie.
     
  16. Photo Engineer

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    Well, you said brownish cast.

    That comes from overdevelopment or from iron hydroxides precipitating from bad bleach. You had the former problem then.

    PE
     
  17. markbarendt

    markbarendt Subscriber

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    So PE,

    If "the blue" were covering the whole paper, most visible in the margins; that would be the spent blix, correct?

    If the blue cast was just in the exposed area would that indicate the developer?
     
  18. Photo Engineer

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    Spent blix, underdevelopment or too much optical brightener. This would probably apply to all areas.

    PE
     
  19. Steffen Alexander

    Steffen Alexander Member

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    Separate Bleach&Fix?

    I'm using a two part blix. Part 1 contains the bleach (Sodium Ferric EDTA) and part 2 the fixer (Ammonium Thiosulfate). Is is possible to use the two parts separately as bleach and fix instead of mixing it?
     
  20. Photo Engineer

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    Yes, you can separate the two at a considerable penalty in rate of bleaching. It will take about 2x the normal blix rate for the bleach step, and the normal blix time for the fix step. To keep contamination down, you will need a wash step in between. If you don't wash, the fix will gradually become a weak blix all by itself due to carryover.

    PE