PVA emulsion

We have ordered PVA (Jade 403) from the same reputable supplier for
years without any noticeable variation in quality. In the last year
we started having some problems that may or may not be related to
each other. The glue seems to be separating with a brown film
floating on top in the supplier's one-gallon bottles. It also has a
sour odor, different than the usual smell of PVA. Finally, we
started seeing mold in our glue pots. Technicians in the unit
experiencing this problem have a good regimen for cleaning glue pots
and brushes. They also date every bottle on receipt and go through
PVA quickly enough that shelf life should not be a problem. Our
supplier did not know the cause but replaced a couple batches of the
PVA that had the mysterious brown film over the last year. We have
since received another shipment with the same problem.

I'm very interested in ideas or experience anyone can share about
unexpected change in PVA from a single supplier, brown film, unusual
odor, or mold.

Andrew Hart
Preservation Librarian
CB#3910, Davis Library
University of North Carolina at Chapel Hill
Chapel Hill, NC 27514-8890
919-962-8047
Fax: 919-962-4450


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                  Conservation DistList Instance 19:1
                 Distributed: Wednesday, June 15, 2005
                        Message Id: cdl-19-1-022
                                  ***