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Cyanotype woes

  • To: alt-photo-process-l@usask.ca
  • Subject: Cyanotype woes
  • From: Keith Gerling <keith.gerling@gmail.com>
  • Date: Wed, 27 Feb 2008 09:37:52 -0600
  • Comments: "alt-photo-process mailing list"
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I'm at the end of a month-long project printing gum over cyanotype and
I seem to have run into a problem.  I'm not at all experienced in
cyano,  but for weeks now I've been getting perfectly scrumptious
prints on Masa using three different batches that I've found laying
around that vary from 6 to 8 years in age.  One of these batches I
mixed up myself, one was from a friend, and one is in Bostick and
Sullivan bottles and all of them perform identically.   Running low, I
mixed up a fresh batch last week with fresh chemicals and distilled
water.  Totally different results.  The old batches gave me deep
Prussian blues almost immediately.  The new stuff produces weaker
looking prints that are much more cyan (greener).  But the biggest
issue is that the prints bleach out in the gum development stage of
the process.  Granted, my well water might be alkaline, and the older
prints did bleach out a tad, but I with red and yellow gum layers I
was getting some of the deepest blacks I've ever seen in any process.
With the new batch everything looks very anemic.  I'm using equal
parts A to B (as before, although I've tried 2 A to 1 B with even
worse results).  Having no scale, I used the measuring spoon method
Chris provides in her book.   Assuming that the math is correct (I
used 8 tablespoons + 1 tsp FAC for 500ml) what can explain this
difference between old and new chemistry?

I'm running out of time, as I have to show this work in two weeks.
Any ideas?  I'm thinking that I have three options"  1) use a more
concentrated solution of FAC, 2) dump vinegar in the gum development
water, 3) finish the project in 6 years when the Cyanotype solutions
have properly aged.