Cyanotype Questions??

Discussion in 'Alternative Processes' started by CarlRadford, Nov 14, 2005.

  1. CarlRadford

    CarlRadford Member

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    Hi folks,

    I've been toiling at the - traditional B&S - cyanotypes tonight and have a couple of questions:

    1. Can you retain highlight detail? I apreciate the process is said to be self masking but I have tried to print the Minster Church image in My Gallery using this process - I have the exposure up to 20mins at the moment and I am not sure I'm going to get there even though the shadow areas of the pews are retaining detail. I am using a brilliant white cartridge type paper. I had coated some Arches Platine yesterday and ran a test with that and got a pretty reasonable result after 6mins even though the paper looked a little odd after being in a paper safe overnight.

    2. How much do different papers - I assume the ph levels - affect the final colour of the image - the Arches Platine appears much paler compared to the brilliant white stuff that I am currently using.

    Many thanks in advance, Carl.
     
  2. donbga

    donbga Member

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    Carl,

    I don't really know what cartridge paper is but I can tell you I've had exellent results with Platine making cyanotypes. The print in your gallery you reference seems a bit contrasty so your negative may be a bit too contrasty. Also how was the negative developed and what kind of film is it made on?

    Keeping trying cyanotype is cheap!

    Don Bryant


    I assume that the B&S kit is the traditional cyanotype formula, you may wish to use 2 parts A to i part B instead of 1:1. The
     
  3. Donald Qualls

    Donald Qualls Member

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    Actually, cyanotype is only slightly self-masking, or so I've read. The Prussian Blue that forms during exposure isn't terribly opaque to the UV light that does most of the work for this process, so you generally need a less contrasty negative than you would for silver or platinum printing-out processes. My best cyanotype prints have been from negatives that scanned and printed well on silver gelatin; which I'd expect to be too soft, contrast wise, to print well in platinum, van Dyke, etc.

    I've also been told that highlights that wash off in development are due to underprinting -- try either printing darker (until the shadow areas start to reverse to a silver-gray) or doing your first development bath in slightly acidified water; these changes were recommended to me, and I haven't had a chance to try more prints since.
     
  4. gbock

    gbock Member

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    That's my experience also. I used to lose quite a bit of highlight detail until I started to add a little citric acid to the water used for developing.

    Gerhard
     
  5. CarlRadford

    CarlRadford Member

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    Thanks guys...

    I'll try the citric acid route - plenty of that work :smile: I also tried the one of Blackfriars Abbey and that hasn't come out too bad at all. I'll try and post it tonight in the experimental gallery.

    All the best, Carl
     
  6. donbga

    donbga Member

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    You can also use plain whit e vinegar in the water, that's what I use, it does increase contrast though.

    Don Bryant
     
  7. Neil Miller

    Neil Miller Member

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    I have double-coated the paper with the cyanotype solution to good effect. I print under a bed of UV lights until the shadows just start to reverse (go greyish) and use citric acid, but the major factor is the original negative: contrasty, but still able to give a decent print on silver, but a little too soft for vandyke and definitely too soft for POP.

    Good luck,
    Neil.

    PS: old manuals that deal with exposure under sunlight often say that to compensate for the negative, one has to place the printing frame either facing the sun or facing away from the sun. I can't remember which is which but have a feeling that contrary to expectations, direct sunlight will give a less contrasty print. Could be wrong, though!
     
  8. John_Brewer

    John_Brewer Member

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    Adding an acid decreases the contrast. I use between 1 - 5ml per litre of glacial acetic acid in the first developing water bath. For flat negatives potassium dichromate can be used as a highlight restrainer. Add a drop or two of 1% dichromate to the sensitizer. Remember that dichromates are dangerous!

    Another method of contrast control is by changing the type/make of paper. This is probably, at least partly, due to sizing. Paper designed for acrilic painting, which is heavily sized, produces a more contrasty image than watercolour paper.

    J
     
  9. psvensson

    psvensson Member

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    Yep, the acidity of the first bath has a huge effect on highlight detail. I've only just started trying out sodium bisulfate (ph around 1) in place of citric acid, but it's clear that with the bisulfate, there is very little image loss in the highlights. So little, in fact, that I'm having problems clearing the print. I estimate that with plain water, neg contrast should be about 1.2, citric acid, 1.5-1.6, bisulfate 1.8-2.0
     
  10. Ole

    Ole Moderator Staff Member Moderator

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    I haven't had problems with contrast or bleaching of highlights when washing in tapwater. But the local water is a little acidic, usually around pH 6.5 or a little lower.

    Instead of dichromate, I have found that a drop of 6% hydrogen peroxide is a nice and safe(ish) highlight restrainer.
     
  11. John_Brewer

    John_Brewer Member

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    Actually hydrogen peroxide appears to give an increase in contrast. What it is doing is rapidly oxidising the print. The same colour will be achieved over time (sometimes days) as it is exposed to oxygen in the air. :smile:
     
  12. Ole

    Ole Moderator Staff Member Moderator

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    John, you misunderstand: I didn't mean that I add the H2O2 in the wash, I add it in the emulsion! Then it restrains highlights by ensuring the oxidation state of unexposed aread.
     
  13. John_Brewer

    John_Brewer Member

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    Oh, thanks for clarifying that Ole. What strength and quantity H2O2 do you use?

    J
     
  14. nze

    nze Member

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    Hi

    in fact any contrasting agent may be use. Dichromate (potassium or ammonium), potassium Chlorate work well so does Potassium alun. I use all of them with goof result and now I only use dichromate as I got a big box of it.

    you may read these 2 artciles by Mike Ware ( Who wrote a book on Cyanotype)
    http://www.mikeware.co.uk/mikeware/Argyrotype_Process.html
    http://www.mikeware.co.uk/mikeware/New_Cyanotype_Process.html
    http://www.amazon.com/exec/obidos/t...103-8616716-6991058?v=glance&s=books&n=507846
     
  15. John_Brewer

    John_Brewer Member

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    Thanks Christian. I particularly like the idea of Ole's suggestion of H2O2 as a highlight restrainer - cheap as chips from any pharmacy- and thus saving dichromate for gum printing :smile: