Barriers against contact corrosion in the tropics

Wendy Claire Jessup <prevcon [at] aol__com> writes


>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.

The corrosion risk at high humidity is more from the solublizing of
organic acids in the wood which will attack the metal, than from
just the moisture by itself. I would not recommend that you use
acid-free tissue or rag board between metal and organic material
because they can act as wicks to transfer moisture (and organic
acids) from organic material to metal.

It's best to keep the air well circulated. Mold prefers still air in
which to grow. A couple of ordinary electric fans in the building
will help to reduce you mold incidence. Good luck,

George Bailey
Objects Conservator
Australian War Memorial
Treloar Centre for Conservation
4 Callan St, Mitchell, A.C.T. 2911
Australia
+61 6 241 6122
Fax: +61 6 241 7998

                                  ***
                  Conservation DistList Instance 10:26
                Distributed: Tuesday, September 10, 1996
                       Message Id: cdl-10-26-009
                                  ***