Can anyone identify this VDB defect?

Discussion in 'Alternative Processes' started by jtsatterlee, Jul 18, 2006.

  1. jtsatterlee

    jtsatterlee Member

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    Can anyone identify the cause of the silver area in the center of the attached VDB?

    I printed this negative this weekend, with one coating, 15 drops, applied with a Hake brush, 15 minutes exposure, and so no issues.

    This print was made with the same sensitizer, applied with the same Hake brush. However, I applied 15 drops of sensitizer, let that dry and applied another 15 drops to see if I noticed a difference in Dmax.

    The exposure of this print was also 15 minutes and the silver area was present when i removed the print from the contact frame.

    The silver area did not change as I processed the print, the other areas demonstrated the expected color changes as I cleared the print and fixed it.

    My Hake brushes are only used for VDb and do not have metal ferrules.

    Prints with single coatings made before and after this print did not exhibit any defect like this.

    This was the only double coating I made this weekend, but have made others on other days and have not seen this issue.

    After the surface of the sensitizer is dry I put the paper in a drying cabinet. I was having issues with grainy prints and reduced the heat (as well as a few other changes) and have not seen any issues with other double or single coats similar to this one.
     

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  2. dmax

    dmax Member

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    Interesting. I have had this happen to me a number of times, and I could never figure out the likely cause. I.e.; aging chemistry, contamination, precipitates in the coating solution, unseen chemical residues in my trays, sloppy coating technique, etc. I just plain gave up trying to figure it out. In fact, I'd be genuinely happy if I could consistently replicate these happy accidents, since I particularly like the effect. The silvered portions have a look midway between a regular B&W gelatin print and a turn-of-the-century contact print from a glass plate. If you or anyone can narrow the variables down enough so that I can make it work more or less consistently, I'd appreciate a PM.
     
  3. juan

    juan Subscriber

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    What paper do you use? I've gotten similar defects, and I've wondered if there is an unevenness in sizing the paper that causes it.
    juan
     
  4. photomc

    photomc Member

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    John, first of all love the print - nice work and good choice for VDB. Next were the trays used ONLY for VDB? If used previously for another process, this could be an issue (i.e. plt/pd). Also, was the print completely dry (I know it was, but ask anyway) because this could be the 2nd coating washed off. If you coat 2x's you might want to coat once with the mix cut 1/2 with water, then full strength.

    I have seen this, but was able to attribute to something I did and was not concerned about it. Check with Matt, he may have some thoughts or some of the other folks might have a thought. Will chekc my notes to see what I can find...btw what paper was this? Could be a problem with the paper, but do not think so.
     
  5. jtsatterlee

    jtsatterlee Member

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    The paper is Cranes Cover Stock. I have been using the same ream of paper for about a month and I have double coated in the past, this weekend was the first time I was going to do a side by side comparision between single and double coating.

    The trays and brushes have been used only for VDB (there are even specific trays for the clearing bath vs the fixer) Actually this defect was present right out of the frame and did not change during the clearing and fixing.

    Yes, the 1st coating was dry before the second coating was applied and the second coating was dry before printing. (I learned the hard way by losing a favorite negative to damp sensitizer)
     
  6. photomc

    photomc Member

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    Ouch!! Sorry to hear that John...and have done that myself. Lessons learned the hard way do stay with us though.

    Since you say that it was like this right out of the print frame, leads me to think it was something in/on the paper. Do you recall if there was anything in that area while the substrate was drying prior to placing the negative on it? That expends my limited knowledge, hopefully one of the more experienced folks will step in with something.

    At least you can rule out trays, and post chemistry...not that is much help. If you hold the print up to light and look at it from the back side, is there anything of note on the paper?
     
  7. donbga

    donbga Member

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    My guess is the problem is created by uneven humidity in the paper, improper mixture of the VDB or an aged solution that is slowly going bad.

    You might aslo try a surficant like 5% Tween 20.

    Let your paper air dry with no heat. Ask Ann Clancy what she thinks the problem is, she might be able to help.

    You may also wish to try different papers.
     
  8. jtsatterlee

    jtsatterlee Member

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    Thanks all.

    It probably was caused by something "uneven" - coating, drying or humidity.

    I hope it is not the sensitizer since it was just mixed about a month ago.

    Don, Ann was standing next to me when I pulled the frame out of the UV Box. Actually, "Miracle" was my negative :smile:

    I will be changing papers, I have used COT320 in the past and really liked it. I do not like how the wet surface of the Cranes separates from the paper base. Cranes was a just a cheaper option for starting. Just RC is a cheaper option to start with before moving to FB.
     
  9. donbga

    donbga Member

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    Well good luck with your Miracle. My version is a color diptych shot on 4x5 Astia. I'll probably make a tri-color gum of it someday.
     
  10. Joe Lipka

    Joe Lipka Member

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    There is a problem in Pt/Pd printing if you apply too much of the sensitizer to the paper. When that happens, the metal "bridges" over the the surface of the paper and you get a solid layer of metal on top of the paper. Shiny spot is the result.

    I don't know if you can get this defect in VDB.