Hot melt adhesives

Has anyone had experience reversing an aged poly(vinylacetate) (PVA)
Hot Melt lining?  The painting I have been asked to treat was lined
to linen with this adhesive in 1980, but recently I have noticed
large (3 x 6 inch) bulges in several areas.  Inspection of the
reverse reveals that the bulges are separation pockets between the
original and lining fabrics. I have not had access to the edges of
the painting to test the adhesion.

I may have to remove the lining if I am unable to warm the painting,
either locally or overall, to reattach the separated areas.  The
painting has always been kept in a stable environment, so I cannot
account for the failure of the lining unless it is linked to
increasing brittleness of the adhesive.

I don't recall the formula for Hot Melt offhand, but I believe it
contained AYAC and AYAA (Union Carbide) with a small amount of
microcrystalline wax.  It was a state-of-the-art, although somewhat
experimental, material in the 1970s and 1980s and was developed by
Bernard Rabin.  Hot Melt went out of favor as Beva 371 (developed by
Gustav Berger) gained acceptance as a non-penetrating lining
adhesive.

Helen Mar Parkin, Paintings Conservator
214-887-3450


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                  Conservation DistList Instance 19:7
                  Distributed: Thursday, July 21, 2005
                        Message Id: cdl-19-7-021
                                  ***