Selenium tone lost under drymount press

Discussion in 'B&W: Film, Paper, Chemistry' started by SchwinnParamount, Dec 21, 2004.

  1. SchwinnParamount

    SchwinnParamount Member

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    Hi all,

    I had a curious experience last week. I printed a picture on Ilford FB warmtone and toned it in Kodak selenium 1:9 so I had a strong color change. I washed it properly and allowed the print to dry. I mounted it on acid free museum board using Seal dry mount tissue and set my Seal dry mount press to about 250 degrees. I sanwiched the print between the board I was mounting it to and another board on top. When I pulled the print after 3 minutes... all my tone color was gone! The print went back to a neutral gray.

    Anyone ever see this before?
     
  2. donbga

    donbga Member

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    That's a new one on me, I selenium tone MGWT for color and drymount and I've never had the problem. But 250 degrees sounds a bit hot. I use the temperature calibration strips to adjust my drymount temp.

    Don Bryant
     
  3. blansky

    blansky Subscriber

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    I use the same paper, etc that you use and have never noticed a shift in color from dry mounting.

    I agree that 250 sounds a bit hot. I use 195 at 2 minutes.

    A conumdrum indeed.



    Michael
     
  4. SchwinnParamount

    SchwinnParamount Member

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    I did wonder about the temperature too. From my chemistry experience, I know that heat energy can have unusual effects beyond carbonizing a substance. I have another print which I have not mounted yet but processed in the same way. I shall mount it at 195 and 2 minutes (or whatever time will make the bond strong enough) and post the result for those who might be curious
     
  5. BarrieB

    BarrieB Member

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    Greetings, I use 210 Deg F. for only 60 Seconds, no problems, Barrie
     
  6. Konical

    Konical Subscriber

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    Good Morning,

    I agree about the temperature. Somewhere around 200 degrees should be right for FB.

    Konical
     
  7. dr bob

    dr bob Member

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    This is complete speculation but could the observed effect be caused by the high temperature changing the surface, thus modifying the quality of reflected light? I cannot believe the selenium complexes have been modified to any extent by the temperture stated.
     
  8. fhovie

    fhovie Subscriber

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    I have never seen this and I mount a lot of selenium toned prints - usually for a little cooler and never more than 30 sec. But never a color shift. I use mostly Forte Fortenza
     
  9. SchwinnParamount

    SchwinnParamount Member

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    I thought as much too. However when the print cooled the neutral gray color remained. How about my washing technique? How long do you all wash a print after toning? I only gave 15 minutes. Was that enough? if it wasn't, could that have caused the heat to delete the tone color?
     
  10. Tom Stanworth

    Tom Stanworth Member

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    This suggestion is not meant to insult you but:

    Were the prints 100% dry before mounted? If you have a split selenium tone, it is far more apparrent in the wet print and can largely disappear when dry. Therefore if yor images were seemingly dry, but not 100%, there may have been further drydown to swallow up the purple hues. A print that is dry to the touch and no longer floppy (but perhaps not as bone dry as it could be) will dry mount perfectly well as it dries out in seconds. Pure speculation, but a thought, as I to cannot imagine that heat would cause the problems you mention. I use a sealmount without adjustable temperature (laminate or dry mount settings only - I use laminate as dry mount is never hot enough for my tissues) and simply use for minimum dwell time required. Occassionally I have had the odd corner refusing to adhere so it has been in and out a few times. Never have I had what you report, weird! To change colour I would have thought that the chemical change would have to be reversed or at least the grain structure seriously altered (as I thought the colour was a result of grain structure and reflectance....), but my lack of of chemistry PhD might render this total rubbish.

    on the subject of temperature...tho one may use supposedly higher temperatures than other, the temperature the print is subject to may not be higher? One may use a thicker print sandwich and lesss time. If you subject tissue to direct heat ie with a tacking iron it pretty well instantly melts or bonds. I therefore hypothesise that if you use the minimum time to get a perfect bond, then the print will have been subject to the same temperature regardless of what the dry mount press dial reads....about the operating temperature of your particular tissue. For me 45s = perfect bond, 35 s= no bond to partial bond (vacuum press). I would have thought that where long dwell times and lower temperatures are used, it perhaps takes that bit longer for the heat to conduct through and reach full temperature?
    Just guessing...
    Tom
     
  11. dr bob

    dr bob Member

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    I assume your washing technique is along the lines set by Ilford? I hesitate to use their process ver batem as it seems a little on the liberal side. However I’m sure it works for most. No. I don’t believe having some residual hypo in the fibers would cause a reverse reaction with the selenium complexes. If it did something like that I would expect some further evidence such as black powder precipitate on the print surface and a reduction of the overall density especially in the lighter gray areas (and possibly some mottling). Check your upper platen: did anything transfer there?
     
  12. gainer

    gainer Subscriber

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    I can't remember where I read about that effect of heating on toned prints, but I do remember experiencing it once. Use the lowest temperature that will melt the shellac for the shortest time. That seems to be what those do who have not had trouble with color change.

    The color of the image may have more to do with particle size, as you will see a difference in color if you use a fine grain developer on the print. Heating may allow particles to join to form larger particles.
     
  13. SchwinnParamount

    SchwinnParamount Member

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    Interesting point. Until now, I always thought my prints were entirely dry when mounted. I did wait at least 24 hours before mounting but a curious thing happened when I opened the press. A small amount of steam came out. Where would that moisture have come from except from the print itself?. That is strange because the print felt and looked completely dry before mounting.

    As far as print color, the print was not split toned. the color change was even across the print and readily apparent.
     
  14. Konical

    Konical Subscriber

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    Good Morning, Schwinn,

    The steam could have come from either the mounting board or the print. It's always a good idea to put the board in the press for a minute or so before starting the mounting process. It doesn't hurt to do likewise with the print itself. Pre-heating (moisture removal) is not always critical with FB mounting, but definitely is with RC.

    Konical
     
  15. SchwinnParamount

    SchwinnParamount Member

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    I reduced the temperature of my press to 200 degrees from 250 degrees. When I did this, the print I was mounting retained its tone. So it turns out that temperature was the issue after all. That's a good thing to know for sure