Silicone release paper

Recently I removed some large mid-20th century collage artworks from
their frames, wrapped them in silicone release paper, and placed
them inside folders made of grey/white board with the white surface
on the inside.  One week later I opened the folders and observed a
light but distinct and exact yellow impression or off-setting of the
wrapped object on the inside surface of the folder.  Also, certain
areas of the collages, that is, certain pieces of paper, have
somehow left lighter yellow impressions than others--as if they
acted like barriers to whatever reaction was taking place.

These artworks consisted of a variety of printed paper sheets and
photographs adhered to typical acidic mat board and other cardboard
from that time.  The adhesives used seem stable and have not
discolored the paper.  I wanted to wrap them to help keep any loose
or un-adhered areas flat and in place as the folders are transported
or opened.  The release paper was both large enough and, to my
knowledge, safe to use for wrapping art works.  The paper is from a
roll 48 inches wide and was purchased many years ago from Talas.  It
appears to be in good condition, is used for many
purposes--including interleaving between large posters and
artworks--and the particular sheets used for these wrappers have not
yellowed.  The yellow off-setting seems to have affected the white
board, but the wrapping paper itself has not changed color.

Several similar artworks were temporarily placed in grey/white
folders at the same time without the release paper wrapping, and
there is no yellowing on the inside of these folders.

Has anyone experienced something similar, and can anyone suggest
what might be occurring?

Harry Campbell
Conservator
Ohio State University Libraries


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                  Conservation DistList Instance 24:26
                Distributed: Thursday, November 18, 2010
                       Message Id: cdl-24-26-025
                                  ***