Vandyke two coats or one

Discussion in 'Alternative Processes' started by dustym, Mar 11, 2007.

  1. dustym

    dustym Member

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    Does anybody in this forum coat paper twice before exposure on the Vandyke
    process if so is there a longer fixing and washing period.

    rgds
    Dustym
     
  2. buze

    buze Member

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    I always coat twice.
    + Make one coat
    + Let stand one minute
    + Make another coat
    + Let stand one minute
    + Hairdry for 2 minutes (ref the other question about moisture)

    It's easy to see the difference : just out the second coat only on half the paper and print... You can get really, really deep brown with Vandyke with double coat and /just/ the moisture level...
     
  3. davido

    davido Subscriber

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    I have been double coating for a while, which works great although you have to be careful of staining or migrating emulsion. Since the coating is heavier, alot of it is sitting on the paper surface and when you do the initial water clearing the darker areas can migrate to the paper white areas (especially if you have thick borders).
    However, just recently I have been doing an intial distilled water coating before a single coat of sensitizer. Dana Sullivan at B&S suggested doing this especially in dry environments. The water opens up the paper and once the paper has dried, it will absorb slightly more sensitizer. So far, I have getting pretty decent results with just one coat of sensitizer.
    As far as using a hairdryer, I wouldn't use any heat. I've heard that it can cause problems (can't recall exactly what).

    david
     
  4. donbga

    donbga Member

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    Yes.

    No.
     
  5. Loris Medici

    Loris Medici Member

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    I'm pretty skeptical about that. Don't get me wrong -> I'm not implying that you aren't getting decent results, but I simply don't believe that you are able to get the same Dmax as if you were double coating -> with just one coat (using standard sensitizer)... BTW, by my (pretty subjective) standards, a decent print has to show the maximum black capable with that particular process - unless it's a foggy landscape and/or deliberate high key image...

    The pre-wet trick is a nice one; it can be used in conjunction with washing face down...

    Regards,
    Loris.
     
  6. Jim Noel

    Jim Noel Member

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    I single coat. I have experimented with double coating and when I measure the D-max, there is no difference, so I don't waste the time and materials.
     
  7. Loris Medici

    Loris Medici Member

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    Sorry Jim, then probably there's something wrong with your exposure time... You're either exposing not enough (double coating usually needs more exposure due to self masking) or exposing too much to the point of solarization and loosing dmax. I never managed to get the good dmax with single coating - unless I tone with gold -> gold toning improves dmax a lot. And please note that when I say good dmax I really mean it... (log 1.35 - 1.4) What paper do you use? I use Bergger COT 320. Whose FAC do you use? I use B&S's. Maybe there's something wrong with my materials!?

    Regards,
    Loris.
     
  8. davido

    davido Subscriber

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    Okay, now it all makes sense. thanks Loris. I have just started using Gold toner and now I realize why I'm getting decent dmax with one coat.

    david
     
  9. Guillaume Zuili

    Guillaume Zuili Member

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    Even with gold toner double coating does a big difference in dmax. I just did a single coating test last night and it doesn't compare with a doulble coated.
    Guillaume
     
  10. donbga

    donbga Member

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    I agree. Double coating gives better DMAX and tonality for me.

    Don Bryant
     
  11. Andrew O'Neill

    Andrew O'Neill Subscriber

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    From the short time that I have been playing around with the kallitype process, I don't bother with double-coating. I tried it but did not see an increase in Dmax. I did however, have a slight increase in speed. I use Rising Stonehenge sized with gelatin. I brush on the single coat, let sit for one minute, and then dry with hair dryer on cool setting.
    Double coating worked better on the same paper without the gelatin sizing. I get a much cooler colour on the unsized paper and warmer on the sized.
     
  12. Kevin Sullivan

    Kevin Sullivan Member

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    Van Dyke can have an excellent Dmax with single coats, I don't know too many folks who double coat for vdb. But it's really going to depend on many factors.

    The type of paper is the most critical variable, on some papers two coats would be essential, but most well-sized papers should do fine with a single coat. The trick is to saturate the surface layer, after it's richly coated then a second coating won't yield any better results. A second coating could even lower dmax (in some situations) by washing more stuff into the middle of the paper where it won't be seen or exposed. Also, double coating runs the risk of scuffing up the paper surface on softer papers.

    Humidity and coating technique are also important. Brushes work better on hard sized papers, coating rods can be more effective on softer papers.

    Hey Loris, are you using a coating rod on the Cot-320? That paper has been really hard sized the last few batches and I find that coating rods don't make the stuff soak in quite as well. It might happen with soft, light brushing too. The effect is a flaky white look in the print, it kind of matches the paper texture. Try throwing in a drop of tween 20 or photo-flo to break down the sizing, or get one of those cheap disposable foam brushes. The foam brushes scrub the surface real nice and make the coating soak in better. The paper is super tough, so with cot-320 abrasion isn't an issue. My guess is your first coat softens the sizing up, then the second coat fills in the gaps. My brother Dana's trick of putting down a coating of distilled water first, then coating the emulsion later (let the water dry completely) would also work in this case. Good luck.
     
  13. davido

    davido Subscriber

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    this is interesting but how do you tell if a paper is hard or soft sized? Is Stonehenge paper hard or soft sized? Or Arches Platine?
    I would say that humidity is hugely important. I'm finding that it's more important than the issue of double coating.

    david
     
  14. Loris Medici

    Loris Medici Member

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    Hi Kevin, I have used both methods depending on image size. I don't have a collection of rods; I use the rod if any of the two dimensions of my image is 10", I use a - correspondingly sized - brush for other image sizes... and don't worry; I'm pretty well accomplished in coating paper :smile:

    I suspect the specific batch of FAC I use could be a reason of this phenomenon; I use the same batch (2 x 500g) that I purchased from you back in 2003. I never managed to mix Vandyke and/or Argyrotype without precipitation with your FAC. When I asked about this to Mike Ware, he was surprised; eventually his FAC (from Sigma-Aldrich) doesn't cause any precipitation. Since not every FAC batches are created equal, maybe that's the cause of the difference between our observations / procedures?!

    Anyway, I don't do Vandykes anymore -> the inconsistency / mixed reports about FAC caused me to put away the processes which need it. Nowadays, I prefer FAO or dichromates as sensitizer :wink: