The silica gel issues were as Buddy stated. They said that they felt that their seal and the paper
they added behind the document would be enough
to keep the atmosphere in balance. They said that
their container would not stand up to a plane
flight, where decompression and loss of temperature are problems, which must be accounted
for in a museum loan package. Silica gel can
buffer the atmosphere when temperature changes
and it will help a slightly leaky package for
a limited time period. If the package leaks and
the climate is constantly too wet or too dry,
the silica gel will, eventually, follow and
maintain the surrounding condition. There are
differing opinions on its use with wooden objects,
and the testing needed to resolve that issue is
not yet complete. As with framing, one has to
guess, as to what is going to happen and try to
deal with the demands, which that future would
impose.
Hugh