From: Robert W. Schramm (schrammrus@hotmail.com)
Date: 08/16/02-05:36:16 PM Z
Judy,
We I attended John Rielly's workshop on conservation of 19th century
photographs he said the most important factor was humidity. Humidity should
be between 20 and 40% which is what all the conservationist literature is
now saying. Second , of course, is UV light. Apparently the absence of water
slows down chemical reactions. For example, in a gel/silver print, sulfur
dioxide in the atmosphere plus water makes sulfuric acidwhich reacts with
the silver to produce silver sulfide which is yellow.
In my archival work I have noticed that 19th century prints seem to hold
up better than mid to late 20th century prints. I'm guessing that this is
because almost all 19th century prints were made by professional
photographers who were careful to thoroughly fix and wash.
Many 20th centurny prints were made by amateurs and a lot by press
photographers who, because of the time factor, did not fix or wash properly.
Bob Schramm
>From: Judy Seigel <jseigel@panix.com>
>Reply-To: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: Re: Permanence of Kallitype Prints
>Date: Fri, 16 Aug 2002 15:44:06 -0400 (EDT)
>
>
>On Fri, 16 Aug 2002, Sandy King wrote:
>
> > Permanence of Kallitype Prints
> > Any comments or suggestions regarding this test would be appreciated.
>
>Sandy, it sounds fabulous, and results will be a serious compensation to
>us all for having lost another year of our lives by the time we get them.
>
>Here are some further thoughts, however. Have you got that blue paper, or
>whatever they call it, to put in with? When calculating change or no
>change would be good to have a benchmark. I have a pack of it but it's
>old... think I got it from.... Light Impressions? Or other conservation
>source.
>
>I also wonder what paper the tests are on. Would results be different on
>other, equally revered paper?
>
>Finally, are you in touch with a photo conservator? What are considered
>to be the factors that deteriorate photos? While survival of the Ride In
>Sandy's Car would/should be reassurance enough for any of us, I figure
>that carbon monoxide and light aren't the only factors: Humidity is not
>good either, right?
>
>Why the choice of the car? Because it's heat and light? What about your
>oven --? I have a vague memory of low oven for X time being used, I'm
>sure for much less than a year, so we wouldn't have to stay on tenter
>hooks so long...:-)
>
>PS. By coincidence I had out some old tests of kallitype and palladium
>toned kallitype with different developers and on different papers over the
>weekend for a friend who plans to begin. The tones and colors really are
>gorgeous.
>
>Judy
Check out my web page at:
also look at:
http://www.wlsc.wvnet.edu/www/pubrel/photo.html
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