[Alt-photo] suggestions about cyanotype curve

Niranjan Patel nirpat89 at yahoo.com
Tue May 23 01:25:42 UTC 2017

Bob:  Not seeing the attachments....:Niranjan.

      From: Bob Cornelis via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org>
 To: alt-photo-process-list at lists.altphotolist.org 
Cc: Bob Cornelis <bob at colorfolio.com>
 Sent: Monday, May 22, 2017 11:06 AM
 Subject: [Alt-photo] suggestions about cyanotype curve
Hi All

I'm looking for a little help finishing a custom curve I've made for Ware
cyanotype printing using Peter Mrhar's method from Easy Digital Negatives.

I'm having problems getting a smooth gradient from steps 0-10. Pure white
is step 0, pure black step 100. My tones from steps 10-100 are pretty
linear, but within the highlights I've got about half the steps pure white
and then there is a steep jump to a value of close to 10. I'd like to find
a way to get a smooth gradient in this part of the tonal range.

Without a curve, all steps from 0-14 are pure white so the curve has to do
a lot of work to introduce a gradient in a relatively small portion of the
curve range. I've tried tweaking with the curve in that range by hand but
without success.

I was wondering if there are other tricks people know of to handle this
type of situation, either chemically, through exposure, development, etc.

My first wash is in 3% citric acid for a couple of minutes, 20 sec in
peroxide solution, then about 25 min in water.

I've attached 3 screenshots for anyone interested showing my pre-curve and
post-curve step wedges (100 steps), and the curve itself (note it is a
pre-inversion curve).



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