Jacquardmod Jacquardmod
Asher, the President of the company, had some nice advice for one of our customers about washing and developing cyanotype. I am going to start posting more stuff like this, which are email questions we get that can be useful for the whole forum. Her question was about how many times should you wash the cyanotype print after it has been exposed.

" Just to be clear, with the several trays of water (good idea) how much washing do you think should be done? Just until the image is clearly developed? Does active washing/wringing work best or is it also a good option to put the exposed prints into a tray of water and let them sit for a few minutes?"

Answer:

"With cyanotype, the first water bath is not a “wash” per se. You can think of this bath more as the “developer” bath. You are “processing” the print, not washing it. During this stage, you are allowing the chemical reaction to occur between the light-sensitive iron salt and the green citrate. A lot that citrate is not used, and washes off the print, thus making the water bath green. You then need another, clean water bath, to “clear” the print of the green. This is more of a “wash” bath.

Ideally, you would have 4 trays:
1. One for the initial processing of the print
2. Another to clear the print and “wash” it clean of the green
3. A dilute bath of hydrogen peroxide will develop the blue to its deepest color immediately instead of over 24 hours
4. Another water bath to clear the peroxide.

That second two baths (3 and 4) are not necessary, but recommended if possible. But I would have at least two water stations. You do not need to wring or work the fabric at all: the prints can just sit in the water."




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CarrieH
Another Cyanotype query...how subdued does the lighting have to be when coating the paper with the sensitizer liquid? Can I do it in a dull room with a small amount of daylight, or should it be quite dark?
likewise, while the coated paper is drying, should that be in total darkness?
thanks....Carrie 
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Jacquardmod Jacquardmod
I have found that because the cyanotype is sensitive to UV light, that really the thing you should be worried about is sunlight, especially direct sunlight.  A little through the window is ok, but you don't want any rays of light landing on it.  

As far as artificial lights, they only contain a small amount of UV, usually not enough to do anything at all.  So, really even in lighted room, you should be fine. The exception might be halogen lighting which can put out quite a bit of UV.  Fluorescent, incandescent, and LED lighting seem to have almost 0 affect in the amount of time that you would coat the surface.  

Now, that does not mean leave it out for many days in a well-lit room.  Over time that small amount of UV adds up.  You should allow it dry in a dark place, and keep it away from light until you are ready to expose.  The other thing that happens is that the air can oxidize the cyanotype to blue beofre you expose it, so keeping it in an airtight bag while waiting to expose is a good idea.  

If it gets air-oxidized it is ok and can still be used, but you must lengthen your washing step to get rid of the dark blue that covers the whole print.  
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CarrieH
Thank you...very helpful...Carrie 😀
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