Re: Tannic Acid

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

John.

www.johnbrewerphotography.com

----- Original Message -----
From: "ryberg" <cryberg@comcast.net>
To: <alt-photo-process-l@sask.usask.ca>
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