Re: Tannic Acid

From: ryberg ^lt;>
Date: 11/11/05-05:07:56 PM Z
Message-id: <001901c5e714$c1e500e0$6500a8c0@computer1>

I have used wine tannin successfully to tan cyanotypes--but only after
reading Kai Hamann's post a few weeks ago. He uses alkali first, then
reacidifies in acetic acid, then into the tannic acid. That middle step is
missing in all of the instructions I have read. Also, I use a MUCH weaker
tannic acid solution than is generally called for--about a quarter teaspoon
to a liter of water. It is easy to add more if things are going too slowly.
Charles Portland OR
Received on Fri Nov 11 17:08:32 2005

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