cyanotype on wallboard/plaster

[spincsr]

I am a sculptor experimenting with cyanotypes. I am trying to work on drywall board (with the paper coating removed) and plaster (that I am pouring). I have had sporadic success, but am having a problem with yellowing after I wash. If I put the developed image in a bleach solution, the yellow goes away, but as it dries, it returns. I have been using gelatin hardened with glyoxal, and have also tried glutaraldehyde, formalin, and chrome alum, and while all produce acceptable images, the yellowing appears. I have also tried spray starch, shellac, and gel medium to seal the plaster, but have not gotten satisfactory results.
I am using the traditional formula with distilled water.
I am trying to determine the source of the yellowing and how to either get rid of it or avoid it in the first place.
Any suggestions would be greatly appreciated.
Cynthia
cynthiareynolds.net

 

[Falkenberg]

It sounds a lot like a test I did. I ended up using a special kind of bonding. It is a fluid kind og glue. It has a blue tone when applied, but it dries completely neutral. I have no clue to the english name of the product. Here in denmark they sell it in the hardware store along with the drywall. It is applied much like a gelatin solution. There was no Yellowing in my test. I did two test, one with the paper off and one with the paper on. I think that the test with paper on was the best.

 

[JBrunner]

Acrylic gesso, like what is used to prime artist canvas works, I have printed to canvas this way. I disliked the texture of the canvas, but had no yellowing. I don't know if it will stick to your substrate without dissolving it, but I would think it might. I believe it can be mixed with acrylic pigment, if you don't want pure white. You might also try bleaching with a dilute solution of sodium carbonate (washing soda, not baking soda) on one of your other methods. very dilute as it will bleach the image as well. Thats a SWAG. It might work, but I wouldn't lay money on it.

Plaster usually contains some phosphates as an agent to control setting. This could be the source of the problem, but IDK. Cyanotype hates phosphates, and yellowing is what occurs when it contacts them.

 

[Akki14]

I think you'll have a hard time getting it to work directly on plaster, as plaster is very alkaline in pH and cyanotype and the resulting prussian blue prefer an acidic enviroment. Otherwise the blue will bleach away to nothing after a short time. This is why we try to avoid papers buffered with calcium carbonate when printing cyanotypes. I believe Mike Ware has written about the history of prussian blue and how artists discovered that prussian blue will not work with frescos and other lime-based pigments without fading away rapidly.

 

[spincsr]

When I use gesso, I get a periwinkle color, pretty but chalky. Is this an exposure time issue or a chemistry limitation? I'd really like to get the intense dark blues more commonly associated with cyanotype.

 

[JBrunner]

When I use gesso, I get a periwinkle color, pretty but chalky. Is this an exposure time issue or a chemistry limitation? I'd really like to get the intense dark blues more commonly associated with cyanotype.

Sounds like your emulsion isn't thick enough on that surface. You could try double coating. Allow the emulsion to dry between the first and second coat. Just a guess, but a likely solution.