[Alt-photo] cyanotype paper

Christina Z. Anderson christinazanderson at gmail.com
Tue Dec 5 03:31:29 UTC 2017


Dear Fernando,

Say hi to Servane for me!

>  do I use Cristina's 1x1 mix 

I shouldn’t have opened that can of worms before I have more data to share. Please don’t let my 10/10 mix confuse the cyanotype “canon” if there is such a thing. I might stick with a 20/10 to go along with Novo’s calculations and also Mike Ware’s p. 92 Cyanomicon II 26%/12%  (equivalent to 20/9.25% or 20/10 close enough).

As my dear friend and mentor Sam Wang sagely advised me, unless there is a compelling reason to switch, why. 

The 10/10 came out of when I tested the extremes of cyanotype from 4FAC:1PF to 1FAC:4PF thinking the excess potassium ferricyanide would fail. I was quite surprised that I preferred the more turquoise of the 1:4, and it was smoother, it absorbed better into the paper, less washout, long tonal range, albeit the DMax was less. But it made me decide to continue testing all the papers at 10/10 and then go back and test at 20/10. 

Surprisingly exposures range the same as they did with the 20/10, or even less, 19-24 minutes typical for most papers.

In 100 formulas from 1844 on, the ratio of ferric ammonium citrate to potassium ferricyanide varies from half as much fac to pf, to sixteen times as much fac to pf, so for me to label anything “traditional” is kind of a moving target.

Also, as far as canvas to use? There is a 100% cotton muslin canvas you might be able to find; I used to get it through Daniel Smith. But you may need to double coat to make sure it absorbs enough solution. I used to buy unsized canvas like that when I was a painter.

Chris


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