Nancy,
  Once "Bynesian Decay" (my prefered term for it) had set in it cannot be
reversed though it can be halted.  Whatever acid reaction has occured is
permanent but by keeping the relative humidity low and the temperature low
and avoiding acid exposure, the decay will stop.  From my readings I
would recommend at temp of 65 degrees F., a relative humidity of 50-60%
and avoid woods, especially oak, and use acid and lignin free paper for
labels, trays etc.
  As important as controlling the temp and RH is also not hitting the
extremes.  Too low a RH and some shells will dry and crack, to high a
RH and mold will start growing.
 Charlie
******************************************************************************
Charlie Sturm, Jr
Research Associate - Section of Invertebrate Zoology
                     Carnegie Museum of Natural History, Pittsburgh, PA
Assistant Professor - Family Medicine

[log in to unmask]