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.

The probable reason that there is not much to find about the effect
of silk on exhibits is that there no effect.  Wool is made up of a
protein called keratin that contains sulphur so woolen materials,
especially if degraded, can be a problem for silver in showcases.
However silk is made up of a protein called fibroin which does not
contain sulphur. As for dyed silk, I have not yet heard of dyestuffs
on silk affecting silver objects and the (English) textile
conservation textbooks do not mention any related problems.

For the record, wool is comprised of the elements C, O, H, N and S.
Silk is comprised of C, O, H, and N.

The wooden boxes may be more of a problem if not sealed correctly
against emissions.

Jennifer Barnett
Historical textile research and consultancy
Oude Looiersstraat 65-67
1016 VH Amsterdam
The Netherlands
+31 20 427 18 27 (phone/fax)


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                  Conservation DistList Instance 17:31
                Distributed: Monday, September 29, 2003
                       Message Id: cdl-17-31-002
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