Replicas of clay objects

Andrei Vainer <consob [at] imj__org__il> writes

>We use transparent PVA (alcohol-based) to protect objects before
>application of silicone.  It is easily removable, either as a "skin"
>that peels right off, or with water.  After application of the PVA,
>and before the silicone, we use Tuf-Lube Hi-Temp NOD mold release
>agent for plastic, manufactured by Specialty Products Company in the
>U.S.  This layer is absorbed by the silicone and doesn't leave any
>remnants on the objects.

Do you mean PVA as in polyvinyl acetate (not water-soluble) or PVOH
as in polyvinyl alcohol (sometimes referred-to as PVA)? Then of
course there is the PVA emulsion which is water-based, and only
water-soluble again for a very limited time.

I think it is the PVOH that tends to be used as a release
agent/barrier layer.  PVA in a solvent would soak into the pores of
the ceramics, I think, and be difficult to remove again, and the PVA
emulsion might not wash off at all.

Sorry to confuse things, but I think different suppliers around the
world seem to use different nomenclatures and that could cause
problems.

Linda S. Roundhill
Art and Antiquities Conservation, L.L.C.
18121 157th Ave NE
Woodinville WA 98072
425-481-0720


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                  Conservation DistList Instance 19:45
                 Distributed: Saturday, March 18, 2006
                       Message Id: cdl-19-45-004
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