Techniques for coating large alt process prints

Discussion in 'Alternative Processes' started by Davec101, Feb 18, 2009.

  1. Davec101

    Davec101 Member

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    I am planning on printing up quite large cyanotype prints 30”x24” and wanted to see whether others had any advice on coating this large. B&S said they would make me a puddle pusher measuring 25” which I hope should help, although I expect there will be a learning curve for such a large implement.

    While surfing I did stumble across video of a platinum printer who uses a rod and a brush to coat quite large prints (http://www.youtube.com/watch?v=gprrYmUCgzw), however I don’t think I will have as much time to play around with the sensitiser as him as the paper I use absorbs significantly more than his.

    There is a lady who is represented by the same gallery as me who prints 80” x 60“ cyanotypes (see pic) and have know idea how one coats that large reliably, however its probably best I stick to half that size for the moment as that is enough for me! :smile:

    Any tips or techniques would be appreciated, thanks
     

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  2. Tom Kershaw

    Tom Kershaw Subscriber

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    David,

    30"x24" is certainly a significant step up in size from your approximately 8"x10"? cyanotypes that I recall viewing. What technical and aesthetic challenges do you anticipate in addition to coating?

    Tom.
     
  3. Davec101

    Davec101 Member

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    Hi Tom

    As far as technical challenges, these will be enlarging my negatives to that size, I have worked up to 20x16 but not consistently. Also calibrating my workflow with a friend of mine who has a completely different set up to me, his vacuum frame is around 8ft x 6 ft and he uses an 3k HID lamp. These should be overcome with practice and a good few step wedges. Obviously handling such large sheets of sensitised paper and developing will be a challenge, aswell as drying.

    Practice will be key and a lot of patience, I expect there to be quite a high failure rate initially, however I think this is part of the course. Silverprint can supply dev trays upto 4 ft, I have found a much cheaper supplier for Cyanotype II which helps, as I will need about ½ litre to begin with.

    In relation to aesthetic challenges can you give examples of what you are you referring to, as I am bit confused as to what you mean. The final print might exhibit more grain, however for prints of 30x24 the viewing distance will be quite different to my smaller work so I am hoping this will not be a problem.
     
  4. Vaughn

    Vaughn Member

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    Air brush?

    Float paper in a tray of Cyanotype chemicals?

    What a great challenge! vaughn
     
  5. Davec101

    Davec101 Member

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    Air brush :smile: did not think of that. Floating is a good idea although i would imagine i would have to use at least a litre of sensitiser in a tray which even though its cyanotype II would be least £80 worth of chemicals which is quite expensive if it were to get contaminated and the like. Might be worth a try though.
     
  6. Vaughn

    Vaughn Member

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    Another possibility is a small paint roller -- the ones that are about 2 cm or so in diameter and about 15 cm long. They would be non-abrasive to the paper. I suppose one could use the full sized ones, but they would absorb a lot of the chemistry. Another possibility would be those paint pads -- rectangular with the fuzz.

    One could practice on smaller sheets of paper (or even full size) using just water and seeing how much liquid is needed and how to get an even coating...or put food coloring in the water for a better visual clue, but the sheets of paper would not be able to be used for the real thing.

    80 pounds for a liter of Cyanotype II!! Ouch! I just worked out how much it costs us to make up 2 liters of the Classic cyanotype formula .. about US$25 (with tax and shipping)...less if the two chemicals are bought in larger amounts.
     
  7. q_x

    q_x Member

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    I've never coated such big sheets, but I'm a mural painter also :smile:.
    Flat big brush and foam roller both will work. With brush you just have to work fast, to have last stroke wet when applying next one. This will make even coat. You can apply several coats, maybe 3 will be OK. Dipping in half-pipe tray with some cylinder weight inside will work (my friend used such thing to seize 100x70 cm sheets), but it will take more solution to cover paper on both sides.
    If you're not in hurry, you can build coating apparatus (with half-pipe tray and overflooded liquid inside), one of this when paper only touches the surface of the liquid, and the surplus liquid is reused. If you need a sketch, I can make it. Feel free to post me to: luke.jastrzebski at gmail. com.
     
  8. Tom Kershaw

    Tom Kershaw Subscriber

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    I'd have thought agitating 4ft trays might generate a few issues but I presume the sensitized paper needs to be processed flat. The Fotospeed price for Cyanotype II sensitizer is £142.49 inc VAT for 1 litre so I presume your new supplier is one that is cheaper than the Fotospeed product.

    In terms of aesthetic challenges I was referring principally to the substantial increase in size.

    Tom.
     
  9. Davec101

    Davec101 Member

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    Yeah 4ft trays would be slightly tricky but am sure its not too difficult. B&S can supply 1 litre for around £76 so its a no brainer really, i am getting used to this sort of cost as platinum costs the same for 10ml !! My friend will print out A1 size transparencys for £12 so i am saving money there which wil help.
     
  10. Davec101

    Davec101 Member

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    Thanks for your advice, I might try some traditional Cyanotype to start off learning how to coat large sheets as it sounds so much cheaper. I will have a check with silverprint to see how much it will be over here.
     
  11. Barry S

    Barry S Subscriber

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    For large amounts of cyanotype sensitizer, it doesn't make any sense to buy prepared kits. Classic cyanotype sensitizer uses stock solutions that combine to yield 10% ferric ammonium citrate and 4% potassium ferricyanide. If you buy these easily obtainable chems, the cost is about $7.50/liter here.
     
  12. Vaughn

    Vaughn Member

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    The prices I worked out for the traditional cyanotype were B&S prices for the Ferric Ammonium citrate and the Potassium ferricyanide. If you can order and ship the chemicals from them (unless you can find a more local chemical supplier), you will need 200grams of the Ferric Ammonium citrate (add to 1 liter water) and 80grams of Potassium ferricyanide (add to 1 liter of water) -- and you will have your 2 liters total. The 200grams of ferric Ammonium citrate is US$19 and 100 grams of Potassium ferricyanide is US$7.00.

    If you don't have a way to weigh out the chemicals, B&S would probably package up 80 grams of the Pot. ferricyanide for you...they are good about that sort of thing.

    Vaughn

    PS...as Barry shows in his post, there are a variety of receipes. Part A in his is 10%, mine above is 20% and I have read another one at 25%. His Part B is 4%, mine is 8% and the other I read was 10%. Whatever works!
     
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  13. Davec101

    Davec101 Member

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    Thanks Vaughn for your post, thats just the kind of info i need, i think float coating would be a good idea to try for 30x24" and above, i imagine one would have to avoid getting sensitiser on the other side of the paper and it would probably require 2 to 3 'floats' in the sensitiser bath. Two litres would am sure be more than fine and at those sort of prices i would definatly give it a try even if its just to practice. What type of blues are you getting with Classic Cyanotype? are they are as deep and rich as the modern version?, my initial tests with the classic formula some time ago yielded quite dull blues and so i switched to the modern.
     
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  14. Barry S

    Barry S Subscriber

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    Sorry if I wasn't clear, but I was giving the final concentrations in the combined sensitizer to show how much chemical is needed per liter. The individual A and B stock solutions are 2X, so that's the same as your 20%/8%.
     
  15. Jim Noel

    Jim Noel Member

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    Beware of airbrushing. You don't want to be breathing the fine mist of the sensitizers. Wear something better than a dust or painting mask.
     
  16. Barry S

    Barry S Subscriber

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    I agree. Aerosolizing the sensitizer would be my last choice for safety reasons. Not that it's particularly nasty, but be kind to your lungs. Considering how inexpensive the sensitizer is if you mix it yourself, I'd just use a trough to coat the sheets.
     
  17. Vaughn

    Vaughn Member

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    Dave, I have gotten some intense blues...double coating helps, and intensifying in an Ammonium dichromate bath can help, too. (Cyanotype II uses Ammonium dichromate in the formula, as well as Oxalic acid). The paper plays a big role, too. Buffered paper ("acid-free") interfers with the process. With platinum printing I use a 5% Oxalic acid bath to acidify the paper for better results -- while I have not done this with cyanotypes, it probably would help when using alkaline papers. I am not a cyanotype expert -- I have made them, and have taught others to make them in classes, but others might have more intense knowledge about the process.

    Multiple float-coats should do the job -- letting the coats air dry between coats. Using a hair drier might be difficult on such a large sheet of paper -- uneven drying might result in uneven second coats.

    Jim brought up a good point...if I were to airbrush, I would actually construct a make-shift fume hood to insure that I would not be breathing the mist. I make a small one when I use acetone for sensitizing my carbon tissue...breathing acetone just ain't my thing...LOL!

    Thanks for the clarification, Barry...I did not read your post carefully enough.

    Vaughn
     
  18. SeamusARyan

    SeamusARyan Member

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    Allan Jenkins

    Hi Dave

    I assume you've talked to Allan Jenkins, as far as I know he float coats his large cyanotypes.
     
  19. Davec101

    Davec101 Member

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    Yeah i heard he does that, a bit too expensive float coating with Cyanotype II, it has been a while since i posted on this thread, at the moment i can coat 24x20 with a rod, it took a lot of practice and patience however at them moment I am getting good coats with a few failures here and there, thank goodness!
     
  20. Tom Kershaw

    Tom Kershaw Subscriber

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    What support surface below the paper are you using, plate glass?

    Tom
     
  21. Davec101

    Davec101 Member

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    Yeah am using 7mm plate glass,quite a large piece about 30x30.
     
  22. Katharine Thayer

    Katharine Thayer Member

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    Sounds like Dave is getting good results elsewise, but just in case anyone is tempted to try these rectangular paint pads, I found them really unsatisfactory; those little tiny hairs shed into your coating like crazy.
    Katharine
     
  23. nick mulder

    nick mulder Member

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    As for custom puddle pushers I've found both neon sign makers and the glass blowers at the local universities chemistry department can make anything you're after.

    Interested to find out how you do it - reckon whatever you end up doing you'll likely have to have a large excess of solution on hand to slush about - collecting the excess for ongoing usage (or not) is a question too (?)
     
  24. Davec101

    Davec101 Member

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    The paper i usually use absorbs the sensitizer in about 3 to 4 passes, what excess their is needs to be mopped up pretty quickly otherwise it bleeds and will leave a stain on the final print, it takes a bit of practice.