Re: Tannic Acid

From: John Brewer ^lt;>
Date: 11/11/05-05:20:17 PM Z
Message-id: <01ea01c5e716$7a76f400$6e842052@john3lfqb5rpyy>

Thanks Charles, seems I may have got my acid and alkali backwards before the
tannin bath.


----- Original Message -----
From: "ryberg" <>
To: <>
Sent: Friday, November 11, 2005 11:07 PM
Subject: Re: Tannic Acid

>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 17:17:30 2005

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