[Alt-photo] cyanotype paper
Christina Z. Anderson
christinazanderson at gmail.com
Sat Dec 2 16:12:24 UTC 2017
You started me on this trend a long time ago when you posted the topic of bleeding and information you had found in patents on the list. Since then I have changed the typical 20%/8% you see quoted in books, including my own, to a minimum of 20%/10% to make sure the ratio is no greater than 2:1 (I know you had discussed molar amounts and yours was 18/8). The sky didn’t fall in.
Then through my research into formulas I found that they were so completely all over the board that I started testing a 4:1 FAC:PF to 1:4 FAC:PF and was surprised how little difference it makes. You still get a print. However, the speed is slower. But the color is more turquoise and less navy (goes more green than red) and it is much smoother.
When I began testing papers for my upcoming cyanotype intensive class spring semester, since I started with the 10/10 I just kept on, to keep apples to apples. When I narrow down to a few select papers I’ll go back to the 20/10 to see if the speed increase is worth it over the smoothness and color I prefer.
When I was using the 20/8 I was also often using 2A:1B or 40:8! No wonder I had bleeding and it was you, Alberto, who saved the day!
PS Another paper I have had great luck with is Clearprint 1020H. 100% cotton. It amounts to about 20¢ for a 9x12! This and Canson U-Sketch/Crob Art have to be about the cheapest (14¢ a 9x12) but the Clearprint specifies cotton and archival and the Canson does not say what the paper is made of. I do tape the paper down when coating. I much prefer it to the lighter weight 100H Clearprint but the lighter weight is conveniently often sold in small pads.
> On Dec 2, 2017, at 12:33 AM, Alberto Novo <alt.list at albertonovo.it> wrote:
>> With vinegar and citric it leans turquoise. With sulfamic it leans purple. Caveat: I am using classic cyanotype at only a 10% ferric ammonium citrate/10% potassium ferricyanide so YRMV, but UVBL exposures are 12-19 minutes with acid development.
> Hi Chris,
> I see that you have switched to a greater amount of ferricyanide, like we discussed time ago.
> Hence, there are some benefits, isnt'it?
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