Loris,
Of course you would not want to expose a good print to sunlight. I was suggesting a test using, I would hope, a print with some flaw that you would not keep. Also, about cyanotype and strong light, the effect is well known. They will come back if kept in the dark for a while. I have not tested this but have been told that they can also be restored with a solution of hydrogen peroxide.
Bob Schramm
Check out my web page at:
http://www.SchrammStudio.com
>From: Loris Medici
>Reply-To: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: Re: Toning Cyanotype
>Date: Sun, 20 Jul 2003 12:45:31 +0300
>
>I don't think that exposing a cyanotype to sun light is a good idea (see
>below). This is not how a fine art print should be treated anyway...
>
>According to Christopher James' book a cyanotype exposed to strong sun light
>will eventually (and definitely) fade. Cyanotypes don't like sun and alkali
>conditions. If fading due to sun light occurs, prints sometimes may be saved
>(in other words: gain their original color) by storing in a dark place for a
>couple of weeks. The author also states that the tannic acid toned
>cyanotypes he made 20 years ago show no signs of deterioration.
>
>Regards,
>Loris.
>
>----- Original Message -----
>From: Robert W. Schramm
>To: alt-photo-process-l@sask.usask.ca
>Sent: Sunday, July 20, 2003 5:36 AM
>Subject: Re: Toning Cyanotype
>
>
>I think the idea that tanic acid toned cyanotype are not permanent is
>another myth like the one about cyanotype itself not being permanent. I have
>some, at least, ten year old cyanotypes that were toned with tanic acid that
>show no sign of fading. I also have a cyanotype postcard with a 1904
>postmark that looks just fine. If you are worried, why not put a toned
>cyanotype in a sunny window for about a month. Cover one half with black
>paper. That ought to give you some idea.
>Bob Schramm
>
>
>