>>> Jayne Holt <[log in to unmask]> 12/01/03 01:59PM >>>
Hello-- a friend of mine on Museum-L forwarded your question about
buffered vs. unbuffered mats.  I am a paper conservator in the
Washington, DC, area.  You mention that the prints are "hand tinted".
By that, I assume you mean they have been hand colored with watercolor
(the usual media for this) and may, perhaps, also have been enhanced
with some glazes.

Since you've done research, I'm assuming you are familiar with the
chemistry of buffering.  The reason for avoiding a buffered mat would
be if you suspect that the media on your print is sensitive to alkaline
conditions.  Certainly some pigments (such as prussian blue) are
sensitive, however, in this context, there is a very tiny amount of the
pigment, compared to a huge amount of other material that would benefit
from a buffered housing (namely- the paper itself).  You need to weigh
the benefits for each component to decide on the best housing.  A good
example of when NOT to use buffered housing:  cyanotypes and early
blueprints (both with prussian blue images) should not be housed in
buffered enclosures.  Many photo conservators recommend against
buffering for all gelatin based photo materials (although some make an
exception for gelatin based prints on paper).

The purpose of a buffered environment is to maintain the slight
alkaline environment of your housing material (giving it a longer
useful life before it has to be replaced).  I would say, without seeing
your prints and assuming they are typical of most such prints from that
time period, that your best bet would be for buffered housing.  The
biggest concern for hand coloring is really exposure to light--
watercolors are notoriously light sensitive.  But that is a whole other
issue, isn't it?

-Jayne Girod Holt
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