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Re: [BKARTS] More recent adhesive research



Greetings to the List,

In recent years, we commissioned the services of an adhesives chemist to
design a proper archival copolymer adhesive, to our specifications.   They
advised that the EVA (or more properly VAE) molecule, mentioned by Susan
Peckham in her post earlier today, would be a good copolymer base with which
to begin the formula.  They stated to us from the outset that the PVA
molecule was inferior for archival and conservation purposes because it
required the addition of unstable plasticizers, normally added to give
flexibility to the molecule, but which hydrolyze to form acetic acid over
time.  In fact our adhesives chemist, with about 30 years of experience,
indicated to us that had the EVA molecule been discovered first, instead of
forty years later, then there would have been no need to have ever produced
PVA.  EVA replaces all of the uses of PVA.  It is innately flexible and
requires no plasticizers added to make it so.  In addition, EVA emulsions
form clear  tough films upon drying without plasticizers, because the
polymer is internally plasticized by the ethylene, but which cannot be lost
by extraction, absorption, migration, etc.  Thus, EVA based systems do not
show embrittlements over time as some PVA based systems have shown.
Moreover, EVA shows specific adhesion to many surfaces, certainly problem
ones, much better than with PVA.

Eventually, after about four years, and after a great deal of testing and
retesting, and tweaking and retweaking by archival and scientific bodies
here in Australia, a result was achieved, satisfying (hopefully) all the
various specification demands by the various conservators, at least here in
Australia.  Furthermore, Jack Thompson, in Oregon, also on this List, gave
us invaluable advice in the latter days of developing this product.

It is marketed at the following conservation materials supplier under the
name of Evasol.  International distribution has not yet been determined.


http://www.conservationresources.com.au/home/products/product.php?pid=198



We have been somewhat reluctant to mention this work to the List, as prejudice often follows when commercial posts come up, but after watching the many posts on PVA in more recent times, we felt that it might be an opportune time to bring a little light to the subject.

Peter Krantz.

************************************************
Book Restorations.
34 Clanville Road,
Roseville, Sydney,
N.S.W.        2069,
Australia.

(P.O. Box 500, North Sydney, N.S.W. 2059.)

Telephone:  +61 2 9416.9900
Fax:  +61 2 9416.6800
Email:  restore@xxxxxxxxxxxxxxxxxxx

Established: 1976

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