RE: pt/pd mounting

[Gawain Weaver <gawain.weaver@gmail.com>]

I am interested in hearing any other responses to this question. I have
never before heard any concern expressed about buffered enclosure materials
for platinum prints, and I don't believe that there would be any problem.
This is a topic in which I have had an interest for some time. I wrote the
following several months ago on a conservation list in response to a
question about which materials are safe with alkaline/buffered enclosure
materials:

There is no definitive list of which photographic processes are most
suited to unbuffered enclosure materials because there is no
evidence that buffered enclosures are harmful. The "list" often
includes cyanotypes, chromogenic prints, dye transfer prints, and
albumen prints. The issue of alkaline materials affecting albumen
prints was first raised in the early 1980s by James Reilly based on
his research at RIT. By 1984, and after further testing, Reilly
retracted his initial statement that alkaline buffering in enclosure
materials is deleterious to albumen prints. There has been no
research since then to suggest otherwise. The other processes have
made it on the list based on theoretical speculation. For example,
it is well-known that a cyanotype will undergo fading by alkaline
hydrolysis when placed in an alkaline solution. Dye transfer and
chromogenic prints can also be negatively affected by such
treatment. However, it has not been demonstrated that the alkali
reserve used in buffered enclosures has any negative effect upon any
of the photographic processes.

There is some concern that in a disaster involving water, the alkali
reserve from the enclosure could raise the pH of the water in which
a print is immersed. Based on such considerations, some have chosen
to "play it safe" and use unbuffered enclosure materials for
cyanotypes, and less frequently, for other processes as well.

Gawain Weaver

Andrew W. Mellon Fellow
Advanced Residency Program in Photograph Conservation
George Eastman House
(585) 271-3361 x325
gweaver@geh.org



-----Original Message-----
From: Camden Hardy [mailto:camden@hardyphotography.net] 
Sent: Saturday, September 09, 2006 1:19 PM
To: alt-photo-process-l@usask.ca
Subject: pt/pd mounting

I've heard a myth I'm looking to bust or confirm, and I figured this would
be a good place to find out.

Someone once told me (can't remember who or where or when) that since
pt/pd is an acidic process that mounting a print in pH neutral or acid
free mat board will actually shorten the life of the print.

So my question is, within the context of pt/pd, how important is the pH
level of mat board for archival mounting?

Thanks,
Camden Hardy

camden[at]hardyphotography[dot]net
http://www.hardyphotography.net