Sizing - got the who, where, why & when just need the HOW

Discussion in 'Alternative Processes' started by nick mulder, Sep 25, 2005.

  1. nick mulder

    nick mulder Member

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    got the all the recommended gum bichromate chems from B&S - no instructions tho on what the gelatin and glyoxal are for..

    as far as I have googled i can see they are related to paper sizing - in which there is myriad talk about the why to size and what to and what not to use for sizing in myriad different scenarios - but as far as i can find there are no instructions on how it is achieved ..

    solution strengths ? which first ? how long ? do you simply immerse the paper in the solution ? do you coat with coating rod ? just leave it to dry ?

    um, errr ?

    help!

    would experiment - but don't want to waste chems or poison (?) myself

    any help appreciated (;

    cheers,
    nick
     
  2. Mateo

    Mateo Subscriber

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  3. nick mulder

    nick mulder Member

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    drunkotype

    Damn,

    thats a good article - i remember seeing the site and those two pic's sometime ago - but that was before I needed to know about sizing so the info didn't soak in so much (heh)

    Ok!

    thanks Mateo

    p.s. Everclear... hmmm cant get that here - shall i add Vodka instead ?
     
  4. Photo Engineer

    Photo Engineer Subscriber

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    It may be no wonder his prints yellow with glyoxal.

    I'm able to harden with a far lower level than he reports in that reference. I use about 18 drops of 10% glyoxal in 30 ml of 10% gelatin. No need for that 40% glyoxal. And, my gelatin is hard by the time it dries.

    I am making conventional silver halide in gelatin prints, and that may make a difference, but it shouldn't make that much difference.

    BTW, Bergger makes a fine rag paper that is pre-sized. Excellent coating quality for many coating purposes.

    PE
     
  5. sanking

    sanking Member

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    Are you talking about COT 320 or does Bergger make a gelatin sized pape?

    Sandy
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    Sandy, the Bergger COT320 is gelatin sized with no baryta. It may be hardened, but I didnt' ask them (it would probably have to be). The labels on some packages are incorrect, indicating baryta content, but I checked with them personally when I placed a large order of 11x14.

    The 11x14 COT320 that I got had new packaging without the 'baryta' being mentioned on the label.

    PE
     
  7. sanking

    sanking Member

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    PE

    Thanks for the information. I knew that it was sized but not with gelatin. I have some on hand and may try it with carbon printing now that I know the sizing is gelatin.

    Sandy
     
  8. sanking

    sanking Member

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    PE,

    When I tried the lick an stick test with my COT 320 there was no stick, which makes me believe there is no gelatin sizing. What is the source of your 11X14 batch that is gelatin sized? Or is it sized so slightly that it will not stick?

    Sandy
     
    Last edited by a moderator: Sep 25, 2005
  9. nick mulder

    nick mulder Member

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    I have some COT320 here - thought tho that gum favored the rougher papers with more 'tooth' to keep hold of the delicate highlight areas

    will try it anyway, using the rougher side, which I use anyway for pd prints - might be interesting to have a high contrast pic result and I'm going to try some half-toning (via photoshop) so the contrast is max anyway (;

    I also just found this:

    http://www.apug.org/forums/showthread.php?t=6248

    which is exactly what I was after - instructions from B&S itself, right here at APUG - heh - unsure why I didn't see it in my searches for 'sizing' - but it was at the bottom of the forum page in the similar threads links ...

    great function that.
     
  10. Photo Engineer

    Photo Engineer Subscriber

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    Sandy, I called Bergger and spoke with John there. He assured me that there was a gelatin size on the COT paper, but he said that there was no Baryta whatsoever.

    Based on his assurance and my trial coatings on some 8x10, I ordered two boxes of 11x14.

    My experience with it coating silver halide in gelatin has been excellent. If it were not for the price, I would use it for everything. As it is, I use Strathmore Smooth for my trial coatings (no subbing) and then the 'best of the best' goes onto the Bergger.

    I just wish I could get some Baryta subbed paper, but anyhow, the behavior in my hands based on my experience agrees with what John said - that there is some level of subbing on that Bergger paper. I agree that it is hard to detect, but I can see the slight sheen on one side as opposed to the other so one side is different. It does not appear to be just due to calendaring. Gelatin seems to spread more easily on the Bergger COT paper.

    PE
     
  11. Photo Engineer

    Photo Engineer Subscriber

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    Nick, only one side is sized. It is the smooth side.

    PE
     
  12. clay

    clay Subscriber

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    FWIW, you may experience some significant shrinkage issues if you use COT320 for multiple printing (e.g. multiple gum or gum over platinum). IME, it shrinks non-proportionately perpendicular to the grain of the paper. To make it into a good gum over paper, I would run it through at least one hot water pre-shrink before printing on it. And this step will probably remove some of the manufacturer's sizing. If you are just doing a single coat gum or a platinum or palladium print, then the dimensional stability is not an issue.

    Also, it was my understanding that COT320 was sized with gum arabic, not gelatin. I think I read this in the Dick Arentz book.
     
  13. nick mulder

    nick mulder Member

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    well that explains a few things (; - I'm getting much flatter yet blacker blacks on the rough side and it does need a few extra drops to get the full coating

    So I'm assuming the smooth side is the one meant to be printed ? I prefer the other... there are so many variables I could be doing two things incorrectly that inadvertantly make it better somewhat ? but not the best it could be ...

    i started this thread WRT gum but I am talking about pt/pd here ...
     
  14. Photo Engineer

    Photo Engineer Subscriber

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    Nick, I'm sorry I cannot help you. I do only silver halide in gelatin.

    I know that the smooth side (calendered) is the side for coating, and the reverse side (wire side in the trade) is not. That is normal papers. This is most differentiated (AFAIK) in hot press papers. Cold press papers are harder to differentiate between the face and wire side.

    The face side is usually subbed with a size coat and in photo grade papers has Baryta in gelatin.

    PE