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  1. #11

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    Quote Originally Posted by Ian Grant View Post
    Are you still using Avoirdupois weights ? 2gr is 2 grains or do you mean grams ?

    Ian
    Grams not grains. Didn't know gr is grains.

  2. #12
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    Quote Originally Posted by R Shaffer View Post
    Grams not grains. Didn't know gr is grains.
    Thanks, while I guessed you probably meant Grams many US books use Avoirdupois weights as well, and surprisingly one recently (in the last 10 years) uses no metric at all, and the convention is to use Gr for Grains.

    The other reason for querying is 4 grams of Chrome alum to 21 grams of Gelatin seems rather high, but then you seem to be saying you soak in water for 10 minutes afterwards, so that would remove the excess anyway.

    My own use of Chrome alum was as a 10% solution and less than 5ml of that for substantially more Gelatin in a subbing layer. The rate in commercial B&W emulsions can be in the region of 4-5ml of the 10% Chrome alum per 3 kilograms of Gelatin, but then they aren't wanting the same degree of hardening.

    Ian

  3. #13

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    ok finally I managed to find some 30% formaldehyde solution over here, quite cheap surprisingly (5€ for 1L). I read some people put "drops" into the gelatin solution, but well it's quite hard to quantify ... is there some proportion / recipe even if just for a start ?

  4. #14

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    Xandros, I've given the proportion I use few messages ago: 0.2ml per 1g gelatin. I soak the gelatin in cold water, wait 15 minutes (15 minutes is perfectly fine for 3%, you may need more time for stronger dilutions...), heat the solution to 40C using a coffee mug warmer (my 500ml beakers fit perfectly on the heating pad), mix the formalin into it, stir and size the papers with a brush. I then discard the excess. 100ml of solution is plenty for any reasonable sized batch...

    Now I don't say that's the absolute correct proportion, all I say that's what works for me w/o any problems...

    Regards,
    Loris.

    P.S. Dry the papers in a well ventilated room!

  5. #15

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    Thanks Loris ! Yep I decided to try formalin because I'm printing in a room with a big window so it should do the trick without endangering anyone

  6. #16

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    Quote Originally Posted by Ian Grant View Post
    The other reason for querying is 4 grams of Chrome alum to 21 grams of Gelatin seems rather high, but then you seem to be saying you soak in water for 10 minutes afterwards, so that would remove the excess anyway.

    Ian
    I used 2g Chrom Alum to 21g Gelatine. Not sure where or how I came up with that quantity. But it does make the gelatin a lovely aqua-marine color and I was able to put 4 layers of gum over a cyanotype without any staining. No water bath after though. I just shuffled the sheets in the tray for 10 minutes in the warm gelatin.

    One thing I did notice is that I did get a little darkening of the cyanotype around the edge of the coated area during drying. It vanished during development and the print looked good ( no fogging ), but I was a bit concerned I had some sort of reaction going on.

  7. #17

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    Quote Originally Posted by Xandros View Post
    ok finally I managed to find some 30% formaldehyde solution over here, quite cheap surprisingly (5€ for 1L).

    Congratulations for finding that formerly very elusive chemical (well, post 9/11?)! I was just about to report here my thrill for finally being able to get a liter of 30% FORMOL from a high profile Paris photographic supplier like Prophot ( i can see it on their website also so i suppose they can deliver by post but im not sure).
    Things seems to be easing up for us alt printers here recently because im seeing more local sellers of chemicals to end users now than when i arrived here (Paris) 5 years ago. I have not had problems with unsized Fabriano Artistico with up to 4 or 5 layers of gum and gumovers but there's that part of me thats not happy knowing im limiting myself to possibilities.
    thank you also Loris for posting your mix and procedure, now i can try sizing!!!!

  8. #18
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    Quote Originally Posted by R Shaffer View Post
    I used 2g Chrom Alum to 21g Gelatine. Not sure where or how I came up with that quantity. But it does make the gelatin a lovely aqua-marine color and I was able to put 4 layers of gum over a cyanotype without any staining. No water bath after though. I just shuffled the sheets in the tray for 10 minutes in the warm gelatin.

    One thing I did notice is that I did get a little darkening of the cyanotype around the edge of the coated area during drying. It vanished during development and the print looked good ( no fogging ), but I was a bit concerned I had some sort of reaction going on.
    I think if it was me I'd do some tests, making up a 10% solution, starting around the ratio as Loris suggest for formaldehyde, maybe a little less.

    Ian

  9. #19

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    Brownman, I was very surprised to see how easy it was (drugstore) and it's a usual plastic bottle like those they use to sell bleach or such basic chemicals at the supermarket ...

  10. #20

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    Xandros, i just saw you are in Brussels. My first batch of important chems came from Roger Kockaerts of atelier PH7 http://www.permadocument.be/texte/LF.../procchim.html He doesn't have formaldehyde listed but i wont be surprised if he have stashed somewhere if you ask him. I would love to pay him a visit again and get more plus get inspired with his impressive collection of alt work personal and from other artists all over the world. Great man.

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