Double coating VDB's - some thoughts

Discussion in 'Alternative Processes' started by Kimberly Anderson, Dec 13, 2005.

  1. Kimberly Anderson

    Kimberly Anderson Member

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    I'm printing 7x17 VDB's today, and am trying to do some double coating as Sandy King has suggested.

    I am using 6ml of VDB solution for the first coating, which might be 1-ish ml too much. His suggestion was 6ml for a 12x20. The 6ml are going on very nice and even for the first coat. The second coat is where the problems begin.

    The paper is warping pretty badly (Somerset hot press), and when I go to do the second coat, I am getting run marks and even some puddling going on.

    I am considering using 4ml or so for the second coating to see if I can eliminate the puddling on the second coat.

    I am letting the first coat air dry for 5-10 minutes, then force-drying it if it's not completely dry for the second coat.

    Any suggestions?

    EDIT: The double-coating produces a very rich deep DMax which is quite pleasing, so I am pretty commited to figuring this out. It seems to be worth it on my early tests.
     
  2. sanking

    sanking Restricted Access

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    Michael,

    You might consider taping the edges of the paper to a hard surface. Also, don't wait so long to put on the second coat. I find that in 2-3 minutes the first coating has dried enough to put on the second coat.

    Sandy




     
  3. fhovie

    fhovie Subscriber

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    You might try a brush - there is a specific watercolor brush I bought that really doesn't soak up much of the fluid and coats a warped surface quite evenly.
     
  4. Kimberly Anderson

    Kimberly Anderson Member

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    I'm still using my 2 1/2inch brush...seems I never bought that Richerson brush after all (still in the plans though...).

    I had been taping down my paper to my Corian counter top, coating one piece, then removing it, taping down a new piece, etc...then coming back to the first ones and doing the second coating.

    I'll try doing the first coating, waiting a bit for it to dry, then doing the second coating.

    Thanks for the suggestions. We'll see how this goes. :smile:
     
  5. smieglitz

    smieglitz Subscriber

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    While I've never made a VDB that large I sometimes print 8x10 on 11x14 Bienfang 360 marker paper which warps considerably when drying. I solved the problem largely by taping the paper tightly around the outside of a large Cibachrome processing tube. It dried much more evenly this way and though it didn't take it all out, it was a great improvement. I suspect a large diameter PVC pipe would work just as well.

    You might also try flattening the coated paper using a drymount at very low heat. This might affect the emulsion, but perhaps not. Worth a try I would think.

    Joe
     
  6. scootermm

    scootermm Subscriber

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    6ml is quite a bit. when I double coat for VDBs I use about that total. for my 717s I coat the first coat at about 3.5ml and then 2-2.5ml on the second coat. If Im single coating its about 4ml total. using a richeson 9010 water color brush.
    works well.

    just my thoughts.
     
  7. Kimberly Anderson

    Kimberly Anderson Member

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    scooter,

    maybe that's why I'm seeing bronzing on this last batch? I'm also seeing some weird mottling and some blotchy color shifts. Up until today the Somerset hot press that I've been using has been very nice, but now with the double coating, I'm wondering if the paper's not holding up as well?

    The 5ml for the 7x17's still seemed a bit excessive...I'll try single coating at 4ml and see where that takes me.

    Unfortunately I just got a commercial job that needs to be done before Christmas. I'll be shooting the rest of the week and won't get to print again for a while.

    Duty calls. :sad:
     
  8. sanking

    sanking Restricted Access

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    For a 7X17 print I use about 4ml for both coating. I also mask off the paper to leave a covering area of about 7 1/2 X 17 1/2.

    However, much depends on the paper, as those that have little sizing, or that have lost the sizing in an acid pre-soak, will soak up two or three times more of the sensitizer than others.

    Sandy



     
  9. Kimberly Anderson

    Kimberly Anderson Member

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    Resurrecting this thread...

    I'm doing some 12x20's today. Using Arches Platine, double coating on the smooth side. Gave the paper a 30 minute steam bath in the bathroom before coating. RH is hard to control here in the winter, it's raining today, could be dry as a bone tomorrow...you never know. I do also have a pot of boiling water where I am coating.

    I have marked off an area 13.5 x 21.5 inches, using 6ml of solution. Coating with the Richeson 9010 brush.

    I am thinking that 6ml is a bit much, and will coat the next sheets with 5ml. There seems to be some excess solution and a bit of puddling near the edges.

    I'll let them dry, make some text exposures and report back.
     
  10. sanking

    sanking Restricted Access

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    If you have a small room where you can coat and dry then a humidifier would be a good investment for printing with iron sensitive processes. I picked up one for $45 at Hope Depot that will raise the humidity in a room about 10X14' by about 15-20%.

    There is no right amount of solution per print area since this depends very much on the paper and its humidity. 6ml is about right for me with most papers when the RH is 55% of more. If there is puddling, just keep brushing until it evens out. Nothing wrong with that so long as the paper has a good size and you don't abrade it with the brush.

    Sandy
     
  11. Kimberly Anderson

    Kimberly Anderson Member

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    Sandy,

    Thanks for the tips. I'm trying to boost the RH in an attempt to get a good print out of a semi-flat negative. It's worked well on the small test-prints I've done. The larger prints that are 12x20 negatives, I don't have a room I can coat in that I can both control the humidity and have a space large enough for the sheet of paper I'm using.

    So...it's always a trade-off. Maybe I'd better spend some time refining the negatives next time eh?

    FWIW...the 6ml of solution that I thought would be a problem with the 'puddling', doesn't seem to be bronzing and it's washing away. Next time I coat I'll brush until the puddles get absorbed and see how that changes anything.

    EDIT: Just did a full-size print. I don't like the puddlng. I'll make sure that I brush till it's absorbed. The 'non-issue' was on the edge of the test prints, clearly the real print was much more 'puddly'.
     
    Last edited by a moderator: Dec 7, 2007
  12. buze

    buze Member

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    I don't understand; if you have puddles, you obviously have way too much solution; so cut it back by half and try again maybe ? You are not trying to soak the paper completely, just coat it... I usualy put just enough per coat so that once I have finished brushing it (4 or 5 passes of vertical/horinzontal) the coat is perfectly even and the brush is getting 'dry', and I just have to stand the paper 1 minute before I apply the second coat with slightly less solution.
    Then another minute stand, a couple minutes of hair dryer and it's ready to expose. Strangely, contrary to everything I read, the 'hot/warm' hair dryer works a lot better than the 'cold'; seems to me to 'hot' air steams some of the moisture of the solution into the paper and I get better contrast that way...
     
  13. Kimberly Anderson

    Kimberly Anderson Member

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    The last batch I did I used 5ml for each coating. Seems to be about right. I don't think cutting it down by half, 6 down to 3, would give me enough liquid to spread around (12x20).

    5 worked well...second coat going on just as first coat is dry to the touch.
     
  14. sanking

    sanking Restricted Access

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    With VDB the negative makes all the difference. There is really no way to make a great print unless the negative has a very long DR. I like about log 2.5, or even slightly more.

    However, there is also no way to get maximum Dmax from the process unless you are working in a room with fairly high RH, above 50% for sure, and above 60% if you can get there. Alternatively, you can humidify the paper in some type of small tent before coating, and then dry the paper in the same environment.

    Sandy
     
  15. Kimberly Anderson

    Kimberly Anderson Member

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    I had not heard that drying the paper with a high RH made a difference in the Dmax. I am quite happy with how dark the blacks are going.

    Consider that my coating/processing area is seperate from the exposure unit, which is seperate from my drying area...all within my home though. I do not know if I can control RH effectively within the entire house. I am considering adding a humidifier to my HVAC system to see if I can't raise it a bit higher
     
  16. sanking

    sanking Restricted Access

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    Have you measured the reflective Dmax of your prints? You should be able to get a Dmax of at least log 1.45, and with optimum conditions and double coating, perhaps as high as log 1.55.

    Assuming a suitable paper of course.

    Sandy King
     
  17. Kimberly Anderson

    Kimberly Anderson Member

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    I'll pull out the densitomiter today. I used Arches Platine, which I have heard is a fairly suitable paper.
     
  18. Kimberly Anderson

    Kimberly Anderson Member

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    Doing some more 12x20's...have a weird red streak through the print. Hair-dryer dried the print, and the red streak is still there.

    Thinking about a re-wash/re-fix. Weird.
     
  19. Kimberly Anderson

    Kimberly Anderson Member

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    I blogged my make-shift process HERE.

    The weird red-streak is 90% gone. I wonder what it is.
     
  20. scootermm

    scootermm Subscriber

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    Michael, those images look great from the digisnaps.

    I can relate to your makeshift process and working conditions.
    I live in a tiny apt... well actually I live in a darkroom that doubles as a living space
    :smile:
     
  21. Brian Bullen

    Brian Bullen Member

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    Michael thanks for the blog entry, I'm planning to start VDB in the next month or so and this really helps. To see is so much easier than to read. The prints look great from here.
     
  22. Dana Sullivan

    Dana Sullivan Advertiser

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    Michael,

    What formula are you using for the Vandyke Solution? If you're using Brown Ferric Ammonium Citrate, you can clean up the highlights by adding a couple drops of 5% oxalic acid solution to the coating mixture. It's a subtle change, but definitely worthwhile to get that extra punch from your images.

    Unfortunately the oxalic acid doesn't do anything if you're using the green version of FAC.

    -Dana
     
  23. Kimberly Anderson

    Kimberly Anderson Member

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    I read about the oxalic acid, but unfortunately I am using the green FAC. I am pretty much done with VDB and am going to move to Ziatype, Pt/Pd and/or carbon next. I want to control contrast now.

    Thanks for the compliments and tips.