Barriers against contact corrosion in the tropics

I am working with an historic house museum in the tropics.  At the
present time the building is unconditioned.  As a consequence the
conditions inside the house follow outdoor ambient conditions,
although at times the relative humidity can be anticipated to remain
higher in the building because of the large amount of hygroscopic
material (both structure and furnishings).  I often will recommend
the installation of barrier materials between objects of dissimilar
materials (ie. metals on wood, etc.) which are displayed in
historically furnished rooms.  Depending upon the institution we've
recommended Mylar, tyvek or acid-free tissue or ragboard.

In this instance, there's alot of contact between dissimilar
materials and would like to recommend barriers, but  I am concerned
about the potential for additional mold growth and am weighing the
risk of contact corrosion against additional mold (there's lots in
the environment already).  Tyvek or Mylar would reduce air
circulation.  Rag or tissue will contribute to the hygroscopic load.

Any comments out there?  Has anyone considered this one way or
another?  Am I "splitting hairs"?  Is my thinking muddy?  Many
thanks,

Wendy Claire Jessup
President and Conservator
Wendy Jessup and Associates, Inc.
210 Little Falls Street, Suite 203
Falls Church, VA  22046
(703) 532-0788
Fax: 703-532-1661

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                  Conservation DistList Instance 10:24
                 Distributed: Friday, September 6, 1996
                       Message Id: cdl-10-24-003
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