Consolidating polychrome limestone altarpieces

Catarina Gersao de Alarcao <catarinaalarcao [at] iol__pt> writes

>The treatment of eight polychrome limestone altarpieces will include
>desalination, stone cleaning and paint consolidation. We will have
>to carry out the consolidation of the fragments after desalination.
>...
>Do you think that applying an ethyl silicate to limestone
>altarpieces is the correct choice?

I am always baffled that people ask such questions on the DistList.
Polychrome stone altarpieces are necessarily very complex objects.
Desalination or chemical consolidation can only be considered in
very extreme circumstances.  Is there truly no alternative?  Are you
trying to strengthen the stone, the stone-paint interface, or both?
Ethyl silicate is unlikely to help in cases of paint exfoliation,
but is certain by its nature to complicate the physical and chemical
systems future conservators will have to unpick. Also, most ethyl
silicate products are suspended in organic solvent: have you fully
assessed the impact the application of such products might have on
binding media, for example?

I apologise if these and other considerations have already occurred
to you and your colleagues.  Nevertheless, in a public posting such
as the DistList, this kind of question must be challenged.

Christopher Weeks


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                  Conservation DistList Instance 19:17
                 Distributed: Thursday, October 6, 2005
                       Message Id: cdl-19-17-009
                                  ***