color difference between homemade and commercially available cyanotype

[Rufus Butler Seder]

I've made good deal of prints using Photographer's Formulary Cyanotype, both on paper and muslin. After I coat and dry these--and before exposure--the dried emulsion is a yellow-green color. Of course, it turns blue when exposed and rinsed out.
I'm wondering why commercially-available cyanotype papers are light blue to start with, not yellow-green. Anybody know the answer to that?
Another question: I've also found that the cheaper commercially available cyanotype paper, the kind sold by toy companies for kids to make "sunprints" , have only a very thin coating of cyanotype printed on the surface of thin white paper--and that these require very little exposure time. But the more serious cyanotype companies provide thicker papers which either have a thicker coating of cyanotype (or which have been coated on both sides) and these require significantly longer exposure time. Anyone know the difference in coating processes and/or why it takes so much longer to expose one than the other?

 

[revdoc]

No replies? Oh dear!

I'd have to say that all I have are theories. First of all, I believe commercial cyanotype paper is sensitised by immersion, which I suppose might make it more sensitive. As for the blue colour before exposure: paper that I coat myself slowly goes blue over time. I would guess that it's usually weeks (at least) between commercial paper being coated and then exposed, so maybe that's why they're blue.

 

[nmp]

I've made good deal of prints using Photographer's Formulary Cyanotype, both on paper and muslin. After I coat and dry these--and before exposure--the dried emulsion is a yellow-green color. Of course, it turns blue when exposed and rinsed out.
I'm wondering why commercially-available cyanotype papers are light blue to start with, not yellow-green. Anybody know the answer to that?
Another question: I've also found that the cheaper commercially available cyanotype paper, the kind sold by toy companies for kids to make "sunprints" , have only a very thin coating of cyanotype printed on the surface of thin white paper--and that these require very little exposure time. But the more serious cyanotype companies provide thicker papers which either have a thicker coating of cyanotype (or which have been coated on both sides) and these require significantly longer exposure time. Anyone know the difference in coating processes and/or why it takes so much longer to expose one than the other?

Interesting questions and I don't have the answers - not knowing what proprietary chemistries they are using to make them last long. My homemade classic brew after coating and drying stains like crazy after a few hours. I would like to acquire these commercial papers and see how they compare with the standard classic cyanotype process. What are these "more serious" type papers that you allude to?

 

[jrhilton]

I would be interested to know how the formula was changed for commercial paper so it lasted in storage. I used to have some years and years ago (got it from an arts shop I seem to recall) and it certainly did last and it wasn’t air airtight package.

When I coat my own paper I quickly dry it and then use straight away. Leaving a few hours and it is impacted.

 

[Andrew O'Neill]

What commercially available papers are we talking about?

 

[removed account4]

Years ago I called the folks at Berkeley who make the sun print paper and from what I remember they told me it is the classic formula they use...if you have questions about their paper or other commercially sold papers... might just call and ask them what they use and the difference. I found it easier just to buy ferri and the green and mix if myself...it’s prob a different color than your hand coated paper because it’s not fresh/ just coated but aged in an envelope...

 

[jim10219]

It's all going to depend. Cyanotypes react greatly to the paper used. The acidity of the paper as well as it's size (not physical size) can play a roll in what colors you get. There are also more than one chemistry for cyanotype prints out there, as well as variations within each chemistry (like adding potassium dichromate or changing the ratio of chemicals). I think the acidity of the water used for development also plays a role, but I'm not sure if that's permanent, or just temporary, and if that just effects density and not color. Kind of like the oxidation effect of hydrogen peroxide.

My point is, I don't think there's going to be one universal answer that applies across the board. So the only way to know anything is to run a test yourself and see how one commercially available paper compares to whatever paper and process you use. I've done a lot of cyanotype experiments over the years, and have gotten a lot of different results from them. Some look pretty similar to one another. Some look vastly different. I remember matte inkjet printer paper had a very bright hue whereas some cold pressed watercolor paper looked almost purple.