Polyvinyl alcohol

I would like to lend my support to Lisa Mibach's call for some
methodical research into the properties of modern PVOH, with a view
to making recommendations in respect of its use in conservation.  I
do not share her optimism that it is any more 'reversible' than
previously.

We have been using PVOH (as described in my previous postings and in
CoOL) for a while now as an alternative to PVAcetate adhesive for
use in making archival quality boxes.  The principal benefit (apart
from ease of manufacture from powder to aqueous adhesive, good
adhesive properties and cost-efficiency) is that it contains almost
no residual acidity through decay and release of acetic acid.  When
making so many archival enclosures for an institution such as ours
(a medium-sized archive service), I prefer not to place a steadily
accumulating problem of acetic off-gassing into our repositories
and, by extension, prefer not to use an acidic decaying adhesive for
packaging photographic materials for instance.  In this context, the
apparent stability of PVOH is very helpful.

We never use PVOH for remedial conservation.  In our tests we have
found that PVOH can be softened with cold water after it has been
used as an aqueous adhesive and subsequently allowed to dry, but we
have not been able to dissolve it, except in hot water.  Thus we do
not use it to treat archives.  Since we have no requirement to
reverse our boxes however, this is not an issue for us.

In conclusion, it is a little alarmist to say that one should stay
"far, far away" from using PVOH in a preservation context.  It has
uses in the way I have described, even if it should not be used for
remedial treatment because it is not readily reversible.

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                  Conservation DistList Instance 11:76
                 Distributed: Wednesday, March 11, 1998
                       Message Id: cdl-11-76-006
                                  ***