Double coating & esthetic issues

Discussion in 'Alternative Processes' started by eggshell, Dec 2, 2005.

  1. eggshell

    eggshell Member

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    I've read with interest about double coating pt/pd prints. I understand it increases dmax and produces better shadow details. May I ask if folks here do it as a regular thing? Or is it done only for certain images? What are the important points to note when double coating?

    I'm fairly new to Pt/Pd. From my very brief experience so far, I find that much of the learning curve is in technical issues rather than visual (esthetic) ones. Lots of problems (coating, drop counts, humidity, fog, graininess, clearing, paper suitability, etc.) came up in the initial stage. I assume more technical problems will surface along the way. But when an image turns out right, it looks right. Seems easy enough; little or no manipulation needed. Mainly tone, contrast, and feel of the print. Somehow I think I am being naive thinking this way? What am I missing?

    Thanks.
     
  2. sanking

    sanking Restricted Access

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    I double coat routinely, both Pt./Pd. and kallitype. However, I dilute the second coating 1:1 with water. So for an 8X10 print I would use 2ml of the sensitizer for the first coating, then dilute the 1 ml with water for the second coating.

    Sandy


     
  3. scootermm

    scootermm Subscriber

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    per sandys exact suggestion above... Ive double coated and there was a distinctly nicer looking image when I did it with Van Dyke Brown printing and the ware cyanotype solution. Have yet to try it with palladium/platinum printing though.
     
  4. rogein

    rogein Member

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    I also double coat and find it to be essential for plat printing. When I first started I tried, as some have suggested, applying a single 'heavy' coating but did not find the results as good. Some have also suggested the benefits of double coating are paper dependent - this may be true but I didn't find it so for the papers I use (Platine/Cot, Cranes). Oddly enough the one thing I do notice is the benefits of double coating are, for me, more apparent when printing in the winter (vs the summer) when the RH is low.
     
  5. Ole

    Ole Moderator Staff Member

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    I learned today that with double-coating van Dykes you double the chances for really screwing things up, but the end result is far better if it's good...
     
  6. Joe Lipka

    Joe Lipka Member

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    Run that by me again?

    Do you mean 2 ml of sensitizer for the first coat. The second coat is only 1 ml of sensitizer, but you add another 1 ml to get you the volume to make the coating easier?
     
  7. smieglitz

    smieglitz Subscriber

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    Although I've never done a Pt/Pd print I have done a lot of double-coated Van Dyke Brownprints and a few cyanotypes, salted paper, and albumen prints. Your comments reminded me that in addition to making the emulsion coat more even and increasing the maximum density, the second coat always seems to absorb and go on smoother than the first. I think this is probably related to the first coat having to soak through the paper's internal sizing and then raising the knap of the paper and allowing the second coat to permeate better. I wonder if those effects could be approximated by simply doing a first coat of water instead of emulsion? Anybody tried that? (I know some workers do a citric or oxalic acid treatment on certain papers to control the pH before applying the emulsion.)

    Joe
     
  8. sanking

    sanking Restricted Access

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    Joe,

    I think the answer to your question is no. Memory is that I tested the concept at one time, but don't have the data now. But you can easily test yourself.

    What I think is this. Double coat, but fix the first coating on the paper quickly with forced air on the print. Not hot, just plain forced air at room temp as with a hair dryer on no-heat. This will prevent the emulsion seeping too far into the paper.

    Now, come back with the second coat. No forced aid should be needed at this point.

    Sandy

     
  9. rogein

    rogein Member

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    While I've not tried doing an actual water 'coat', during the winter when the RH is low around these parts, I often pre-humidify the paper *before* the first coat is applied giving slightly better results. Basically I'm trying to match my 'ideal' coating/printing conditions that I get in the 'summer' months - ie. 22C, RH 60%
     
  10. sanking

    sanking Restricted Access

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    The first coat (for 8X10 or equivalent size) has 2 ml of sensitizer, 1 ml of ferric oxalate, 1 ml of metal salt. The second coat has 1 ml of sensitizer (FO + metal salt) plus 1 ml of water.

    The advantage is that you don't use quite as much of the sensitizer but Dmax is as great.

    Sandy


     
  11. eggshell

    eggshell Member

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    Thanks for the tips. Appreciate it.
     
  12. eggshell

    eggshell Member

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    Today I did a double coat as per Sandy King's instruction and saw a big improvement in the print quality. Those few prints I made recently aren't good anymore. Looks like double coating will be routine for me. Thanks to all.
     
  13. marko_trebusak

    marko_trebusak Member

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    Is this double coating thing only relevant to DOP Pt/Pd, or will it work with Zia too? I remember from "New Palladium Print", that authors opinion is that it's not worth the effort and expense.

    Marko
     
  14. eggshell

    eggshell Member

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    I think I read what Nze said somewhere in this forum that you could get a good black with zia without double coating.
     
  15. nze

    nze Member

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    Hi

    Double coating bring nothing to Zia. In the test I made the double coat was not as good as the single coat print.

    But double coating bring 3 things:
    1. deeper black
    2. smoother tone
    3. and it change the curve of the process (for pd/pt) making more straigth in the low light

    With zia you get the deeper black and smoother tone without double coating and the curve is quite different to the DOP curve due to the self masking effect.

    The only thing I sometime find interesting is to coat , expose, coat, expose then clear a ziatype. In this way I get 1.8 Dmax on Arches palatine paper and as for gum it build all the tone.
     
  16. eggshell

    eggshell Member

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    Thanks for confirming that, Nze.