U of S | Mailing List Archive | alt-photo-process-l | Re: Mottling in lighter tones in cyanotype?

Re: Mottling in lighter tones in cyanotype?

Hmmm, Brian,
I have had graininess crop up occasionally and I wonder if this is the mottling you are describing--is it the size of, say, moles?

However, I found that graininess was more prevalent if I used a thicker layer of solution--it actually was just settling down into the paper valleys in a thicker amount and then printing out deeper blue there--which is what Cor and Loris are saying in a sense--because those areas of valleys would essentially have more moisture in them as well as more solution and therefore expose darker.

I do, now, let my paper dry completely which is not hard to do in MT at 15-20% humidity. Usually I wait an hour.

Cor, the dilution thing was an academic one that was being used to test other things, but both Sam and I found that more water to the mix (and the therefore increased proportion of pot ferri to FAC??) made a smoother print. It was an odd finding I did not expect, but my guess is that it might also have to do with better even absorption into the paper with the extra fluid as well as less FAC per sq. in. I think it is the FAC that is the big molecule stuff and so I was diluting the FAC with the water and keeping the pot ferri constant to the diluted FAC.

These are all speculations of course. I am not a cyanotype-Mike-Ware expert, I just do a heck of a lot of it.


Christina Z. Anderson
----- Original Message ----- From: "Loris Medici" <mail@loris.medici.name>
To: <alt-photo-process-l@usask.ca>
Sent: Thursday, January 22, 2009 1:55 AM
Subject: RE: Mottling in lighter tones in cyanotype?

Cor, with cyanotype the correct exposure time is very sensitive to the
moisture level (both paper and working area) and the print-out is not easy
to interpret (especially for delicate highlights). So I opted to use bone
dry paper, ruling out the moisture parameter from the equation. Now, my
success rate is 2x higher than using non bone-dry paper.


22 Ocak 2009, Perşembe, 10:48 am tarihinde, C.Breukel@lumc.nl yazmış:
I think your drying might be the problem: Cyanotype is a printing out
process, I assume it needs some moisture in the paper it self. I never
use a hair dryer and I let it dry at the air for 10 minutes or so: I
start printing when the paper feels dry on the emulsion side. And I do
not dilute..

Good luck,