Rivets in exhibit cases

In assessing the damage done to the Texas A&M wildlife biology range
after their disastrous flood at the end of October (anybody need more
details?), we found that some of the cases of birds and mammals showed a
sulfur-yellow, apparently crystalline powder around the rivets at the
front of the case.  These are quarter- and half-unit steel specimen
cases.  We did not find it in all the cases--only in those with lift-off
doors, and not all of those.  What made it interesting is that an
apparently identical problem had been noted in our own vertebrate cases
at UT over a year ago.  Our higher vertebrate collection is relatively
inactive, so the Weird Yellow Rivet Powder could have been there for
years, but the collections manager at A&M does not remember the problem
in his cases happening before the flood.  We have since found the powder
in an invertebrate specimen storage case and have an unconfirmed report
from Texas Tech.  We've taken samples for analysis, but the amount of any
one sample is (as you might guess) small.  What we want to know is this:
has anyone noticed this before, in similar or in disparate collections?
All we can find that the collections have in common is their fumigation
histories: all were fumigated in the cases with DDVP, PDB, and Dowfume
as a matter or record, and who knows what off the record.  Perhaps the
gasket is breaking down (the gaskets are as hard as rocks in these
cases) and releasing sulfur compounds? It is not pyrite.  The rivets
respond to magnets and are probably either iron or steel.  Paint on the
surface makes no difference.  We are building up a database on this.
Thanks in advance for your help, and happy Solstice.

Sally Shelton
Natural History Conservation Lab
Texas Memorial Museum, University of Texas

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                  Conservation DistList Instance 6:32
                Distributed: Saturday, December 12, 1992
                        Message Id: cdl-6-32-002
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