Silk and metals

Hilda Abreu de Utermohlen <h.abreu [at] centroleon__org__do> writes

>I would like to know the potential effect of exhibiting underwater
>archaeological bronze and silver metal objects over silk-lined
>polystyrene mounts, which are placed in open wooden boxes inside the
>exhibit case. I am concerned that being silk a sulfur-containing
>material, it may corrode the metals in contact with them. But I
>couldn't find much in the literature about silk and its effect in
>exhibits.

Despite contained sulphur, about a third of silks pass accelerated
corrosion tests with silver.  Placing the metal in direct contact
with the silk may accelerate the deterioration of the silk and cause
more emission of sulphur based gases.  In the small number of tests
that I've done, some materials that have caused no corrosion in a
standard (airborne) test fail when placed in direct contact with
metals.  I think you really do need to test the actual silks you are
intending to use.

David Thickett
Conservation Scientist
Collections Care Team
English Heritage
23 Saville Row
London W1S 2EZ
+44 20 7973 3322
Fax: +44 20 7973 3209


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                  Conservation DistList Instance 17:31
                Distributed: Monday, September 29, 2003
                       Message Id: cdl-17-31-003
                                  ***