Sizing paper

Discussion in 'Alternative Processes' started by Fulvio, Oct 20, 2005.

  1. Fulvio

    Fulvio Member

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    How do you size your sheets of paper?

    I have here cornstarch and about 1kg of gelatin a friend gave me. This gelatin isn't made for food... but we don't know how to handle it. It comes in small amber colored pearls.

    While my books mention gelatin sizing procedure, I'm not sure about the quantities of gelatin to mix and if my gelatin is ok. Also, is it mandatory to harden a gelatin sized paper with formaldehyde? If not, I'd like to avoid, because of its high toxicity. Are there alternativel hardeners?

    How about cornstarch or arrowroot sizing? Since they're organic compounds, will they alter the sensitizer or the paper archivability? Do they require hardening?

    Finally, is there some resource on the internet about this matter?

    thanks
     
  2. Jorge

    Jorge Inactive

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    Usually and depending on the paper some people use gelatin solutions from 3 to 5%. Soak the gelatin in water for about 30 mins to an hour and then heat it slowly and to no more than 140 ºF or you will denatuarate it.

    Just in case, a 5% solution would be 5 gram of gelatin in water to make 100 ml.

    Good luck.
     
  3. John_Brewer

    John_Brewer Member

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    I size with 3% gelatin coating the paper generously once with a brush. When this is dry I harden with a 5% folmadehyde solution - this I do outside with gloves on and hang the paper on the washing lone until it's dry. I do a batch of 20 sheets at a time.

    Cheers
     
  4. Fulvio

    Fulvio Member

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    thanks for the answers...

    Yesterday I first tried with a 5% cornstarch solution on a Fabriano Artistico 300gsm. I didn't notice differencies in cyanotype printing. I will do some test with the synthetic gelatin I have... I'm just a little worried about the formaldehyde... Can I use alum as hardener? Or is it good only for organic gelatin?
     
  5. nze

    nze Member

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    Fulvio

    Sizing fabriano artistico will not show great difference. For this paper you will need a 1% gelatin solution. But on paper like Johannot , or some BFk a 5% sizing truely make a difference. Because these papes are more absorbant the image look flat and soft, the sizine help to keep the solution on the top of the paper and result in better density image and sharper too. I 've never use organic gelatin, but just know that if you use potassium alun you may wash the paper after this bath, if not tit wil give momore contrast to your print.
     
  6. Fulvio

    Fulvio Member

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    Thanks Nze,

    what led me to try sizing the paper is the fact that my prints are much, much better with a German paper I have here... Schoellershammer. Unlike others I tried, it is hard gelatin sized (internally & externally). Both Cyanotypes and Van Dyke Browns are much better on this paper than any other I tried (Fabriano, Arches, Magnani...). So I guessed that the key is in sizing, at least for these printing processes. I don't know if the gelatin on the Schollershammer is organic or synthetic, though.

    Fulvio
     
  7. John_Brewer

    John_Brewer Member

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    Fulvio

    With cyanotypes I don't use a size on Arches Aquarelle although I am aware some do. If you are only coating once with the cyanotype mix I don't think you need harden at all. Some people when multi coating apply an unhardened size between emulsions.

    Cheers

    John.
     
  8. Fulvio

    Fulvio Member

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    I always double coat with sensitizer. Arches Aquarelle is generally fine, but with this Schoellershammer (6G) I can get a bit more density - the difference is subtle. I must say that I've tried only the Aquarelle with rough surface because it was the only I could find here. The other paper from Arches I tried is the Platine, which didn't impress me at all so far.

    Which kind of gelatin is advisable for ferric sensitizers - organic or synthetic?
     
  9. John_Brewer

    John_Brewer Member

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    When I said coating once I may have not been very clear :wink: If you are not recoating after development I don't think you need harden the size.

    The Arches Aquarelle I'm using is the hot pressed stuff. It looks nasty when wet, lots of regular watermark type marks but I love it once its dried.

    Cheers

    John.
     
  10. nze

    nze Member

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    I think it also depend on the paper weight. Print on thin paper are often sharper and denser than on heavy one. Crane's kid finish give excellent result in sharpness and density partly due t his low weight.
    I also get excellent result with some extra thin Gampi japanese paper .

    By the way I will be pleased to know which magnani paper you use???
    I find a seller of this paper in France but don't give it a try fas he just sell it by 100 sheets pack. I hesitate between velin , incisioni or pescia. Incisioni should give the sharper print as it is a hot press.

    Schoellershammer paper was used by manuel alvarez Bravo but which N° did you Use??

    I know I am curious but I appreciate to learn.
     
  11. Fulvio

    Fulvio Member

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    yes, paper weight matters
    I've done decent cyanotype prints on very cheap commercial Fabriano papers (<90 gsm). But when the paper is too thin there's always the risk to break it while soaked in water. Perhaps one may try sizing these too...

    I don't use Magnani regularly, just tried it once - it was the one for "incisioni"...
    has a very nice texture, worked well for cyanotype and produced enough density as other papers compatible with cyanotype chemistry. You may like it or not like it if you're looking for some particular tone, density, etc. Personally my favourite choice will be Schoellershammer No. 6 G for regular Cyanotypes with high density and contrasty prints. On the other hand this Shoellershammer doesn't react well with bleaching agents (chlorine, sodium carbonate...). The image washes out without revealing any pleasent blue/yellow split tone or blue/green tone with heavily overexposed prints. Also toning with coffee or tea doesn't work well. I've still to try with tannic acid but I'm don't think it will be good. Other papers react much better when you decided to mess again with a printed cyanotype. However I still have to select a paper for these purposes; low weight Fabriano 5 seems to work, but I want to try the 300gsm version.

    If you can buy few sheets of Magnani it is well worth the try - and probably the paper is good also for many other printing processes, so it won't be wasted if you don't like it with cyanotypes. If you have access only to 100 sh packs I think you could save that money for another paper you already know well and can buy confidently in large stock.