Brown spots on RC prints

Discussion in 'B&W: Film, Paper, Chemistry' started by BetterSense, Jan 2, 2013.

  1. BetterSense

    BetterSense Member

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    Using Arista .EDU ultra glossy RC paper, I have had brow spots turn up on finished prints. The spots are not visible when making the prints but reveal themselves after the print is dry. I have had some of them visible only hours after drying, and some of them not show up for many months. This has only affected about 1% of my prints. The spots are fuzzy, brown, translucent, typically small, and typically near the edges.

    This only has happened to a small percentage of my prints so it's probably something I'm doing rarely or randomly. To help narrow the cause down, what factors could be causing this? Could it be caused by developer being too old? Could it be caused by developer being carried over to the fixer? Could it be caused by old fixer or by insufficient washing?
     
  2. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    Do you use a stop bath?
     
  3. R.Gould

    R.Gould Member

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    Could be caused by incorrect or insufficient washing,make sure the prints stay seperated when washing and wash for 5 minutes, under running water
    Richard
     
  4. BetterSense

    BetterSense Member

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    I use Dektol, stop bath, and Ilford rapid fixer mixed film-strength (4+1).

    I have been considering going to 2-bath fixing and 2-bath washing, just because of this very rare problem, but I would like to identify the actual mechanism that's causing it i.e. the chemical mechanisms that could lead to the brown spots. I don't want to change my fixing regimen if it's actually developer causing it.

    I do use my Dektol until it is very old and brown. I find that this improves the image tone with this paper, but could that be causing my spots issue?
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    Either bad fixing or bad washing. Probably the print(s) float to the top of the wash tray or something like that. Air bubbles can form on the print during washing and prevent complete washing.

    Make sure that you use a fix and wash test for your prints, and make sure to agitate them well in the fixer and in the wash.

    PE
     
  6. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    I'm under the impression that it doesn't really matter what state your developer is in, as long as it is completely neutralized in the stop bath before it goes into the fixer.

    PE's air bubbles advice below sounds plausible.
     
  7. Oren Grad

    Oren Grad Subscriber

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    You shouldn't need 2-bath fixing or washing for RC.

    How do you handle the prints in fixing and washing? Do you run them individually or in batches? What sort of washer do you use? How do you shuffle or agitate? Can you be certain that all parts of the paper remain submerged throughout each processing step? Spots of incomplete fixing or washing near the edges suggest that the paper may be curling upward with the edges poking through the surface of the solution.
     
  8. BetterSense

    BetterSense Member

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    I typically let the prints soak in a try of water while I print. When I get a few, I rinse them in the same try with multiple changes of running water. Before hangup the last thing I do it a very deliberate wash of each print in running water right from the hose, making sure to rinse my own hands/fingers.

    It could be that the spotted prints occur when something breaks down with this procedure or I get sloppy. Maybe a second washing stage tray or proper print washer is in order.
     
  9. David Brown

    David Brown Subscriber

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    That might help. (IMHO)

    Why? Dilute the Ilford fixer for the paper strength (9+1). Especially with RC paper, you don't need the extra strength and it would theoretically require more washing.
     
  10. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    The rationale for using stronger fix is that you can fix the paper for a shorter period of time, which makes it easier to wash out than if it's immersed longer in weaker fix. I'm not sure whether this is needed with RC papers, though.
     
  11. David Brown

    David Brown Subscriber

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    OK, I could be wrong about the washing. But the time for Ilford rapid fixer 1+9 is 60 seconds for RC paper.

    Maybe it just makes better sense to have a "proper print washer" ...:wink:
     
  12. Bertil

    Bertil Subscriber

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    I tend to think that Thomas may have a point in his question about stop bath.
    I once also had problems with brown spots (dektol and Kodak Polykontrast FB) but disappeared when I was more carefull with a proper stop bath using for 1 minute.
    /Bertil
     
  13. CPorter

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    I suppose you are not using selenium toner because you didn't mention it, but brown stains after selenium is an indication of residual silver on the print due to inadequate fixing.
     
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  15. Photo Engineer

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    The rational for using concentrated fix for RC prints is rather meaningless as the support does not suck up fixer, and the emulsion is fixed when it is fixed and thus can wash out in short or long times depending on concentration.

    HOWEVER, the argument fails when we get to FB paper. There is an affinity between the fibers and the Baryta subbing for Hypo and Silver Hypo salts and this means that you can require much longer times for FB paper if you use concentrated fixer. I suggest that in this case, you follow the manufacturers recommendations.

    PE
     
  16. Oren Grad

    Oren Grad Subscriber

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    When you rinse the prints in the tray do you manually shuffle them to make sure all surfaces continually see fresh water?

    In general, extended wet times with RC are not a good thing, since they increase the risk of edge separation and internal contamination. Variable wet times - which is what you get when you gradually accumulate prints in the rinse tray as you go - mean the different prints are seeing different conditions and make it more difficult to troubleshoot.

    I don't think that's quite right. Ilford's early promotion for its RC papers emphasized the convenience of running a complete processing cycle in 4 minutes. Keeping the fix to 30 seconds with film-strength fixer is part of what makes that possible, because the fixing time is part of the cycle time.

    Interestingly, it wasn't safe to do that with Kodak RC papers. In my own tests, Ilford RC papers have consistently cleared in about 15 seconds with fresh film-strength rapid fixer, making the 30-second recommended fix time reasonable. OTOH, Kodak RC papers often needed longer, which explains why Kodak used to advise a longer fix. I wonder what it was about the formulation of the emulsion that was responsible for that difference. They also advised a longer wash, which raises its own questions and complications.
     
    Last edited by a moderator: Jan 4, 2013
  17. wildbill

    wildbill Member

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    I've had what looked like rust colored dots on fiber prints when I lived in california. These were selenium toned. Usually I didn't see the one or two spots in a print until they were coming out of the final wash. I never figured out what caused it.
     
  18. fotch

    fotch Member

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    As stated: When all else fails, fall back on the KISS principal and just follow the mfg. instructions.
     
  19. BetterSense

    BetterSense Member

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    I admit that I am quite sloppy about stop bath. I use it until it is quite tired and almost never stop for a full 30 seconds.
     
  20. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    There's a lot to be said for that. In combination with insuring that washing methods are good, meaning the entire paper surface gets washed thoroughly, and air bubbles are not present.
     
  21. fotch

    fotch Member

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    Perfect practice makes perfect.
     
  22. Photo Engineer

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    Oren Grad;

    I don't say what I have not tested! And, Kodak never recommended the same procedures that Ilford did, and it is due to the emulsion and not the RC itself. The emulsion is fixed when it is fixed, and washed when it is washed. Use a retained hypo and a retained Silver test. I do! I ran extensive keeping tests with Kodak and Ilford paper during the work on TF-5 and SuperFix VII. Kodak paper was slower in all regards (fixing and washing). But then the Kodak tests are moot now aren't they?

    PE
     
  23. Oren Grad

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    Indeed, we've reached the same conclusion about the materials, based on our respective tests. My point was just that the rationale for concentrated fix was not "meaningless" just because it's RC paper - it's an important part of what makes possible the extremely short processing cycle for Ilford (and also many other brand) RC papers. In turn, that helps make a one-print-at-a-time RC workflow efficient enough to be practical. For some of us that's a very tangible benefit. That's all.
     
  24. Photo Engineer

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    I have seen wash times as low as 15" with special fixes and RC paper. It still takes 1' though with normal fixes. With FB it always takes longer. This is based on tests with the standard indicator solutions followed by a 5+ year keeping test.

    PE
     
  25. BetterSense

    BetterSense Member

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    Well, I'm sure that I fix my paper for long enough and mostly sure I wash it well enough. I often fix my paper for many minutes, so I'm going to assume that under-fixing is not a cause, unless I have sometimes allowed my fixer to become exhausted. That's why I was thinking of moving to 2-bath fixing, because it seems like a pretty bulletproof guard against fixer going exhausted.
     
  26. Photo Engineer

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    If you have brown spots, you have done something wrong. You can get those spots with a 2 bath fixer as well if you do something wrong.

    PE