From: Sarah Van Keuren (svk@steuber.com)
Date: 11/25/00-08:37:22 AM Z
> I had fantastic luck salvaging lots of my cyanotypes that were too dark by
> toning them with tannic acid. You have to bleach them out first with
> ammonia, then redevelop them with the tannic acid. (lots of work and very
> time consuming) Each one came out somewhat different color-wise, from a
> more metallic blue, to purple to black and even varying shades of brown.
> I got the info on how to do it from Boston & Sullivan.
Stephen, if you subscribe to Post-Factory Photography edited by the List's
own Judy Seigel, you will find in the latest issue, #5, a very helpful page
on toning cyanotypes. I used to bleach with ammonia or household bleach but
didn't like the fumes. Now, using a mere teaspoon of inexpensive odorless
sodium carbonate in a half gallon of water I can even more effectively
bleach cyanotypes and then tone in tannic acid. We have switched to this
method at the University of the Arts in Philadelphia to the satisfaction of
all including a student who has an allergy to chlorine bleach.
Sarah Van Keuren
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