Adhesives

Peter N. Krantz <bkfndrs [at] ozemail__com__au> writes

>Here in Australia, we are in the process of commissioning an
>adhesives chemist to produce a water-reversible, buffered,  EVA
>(ethylene vinyl acetate copolymer), for use by bookbinders and
>conservators alike, similar to the proprietary products offered in
>the USA and the UK. Our own research has showed us that EVA is
>superior to PVA for various reasons, one important reason being that
>significantly less acetic acid is formed whilst not in use.
>...
>Approaching various parties involved in conservation products here,
>we have been receiving feedback that some conservators in Australia
>are not sufficiently knowledgeable about EVA to feel confident about
>moving across from the traditional PVA.

In 1983 I developed an EVA copolymer adhesive for laminating Museum
Board and Archival Boxboard. An EVA or VAE system was chosen because
of its lack of Plasticisers and resistance to acid hydrolysis. It
was decided to add .5% of calcium carbonate as a buffer.

My aim was to find the safest possible laminating adhesive and my
research led me to an adhesive chemist called Tony Openshaw who,
after listening to all of my requirements, suggested a specially
formulated EVA copolymer which would meet our requirements.

At the beginning of the 1990s, following reports of problems being
found in manuscripts being stored in boxes made in the 1960s using
PVA adhesives which appeared to be breaking down and giving off
acetic acid, I decided to offer the EVA adhesive for sale in small
quantities: it is sold under the name of EVACON-R and my company
<URL:http://www.conservation-by-design.co.uk> now supplies it to
many institutions and individual Bookbinders and Conservators. One
of the institutions tested a range of adhesives and found EVACON-R
to be amongst the most stable of those tested and I would be happy
to supply a copy of this test and some client names as references
upon request.

It is our experience that an EVA copolymer adhesive cannot replace
all of the uses of PVA but where it can our clients have been very
happy with its performance.

My company uses many forms of this adhesive and if Mr. Krantz was
able to buy in bulk it might be more economical to ship the original
adhesive from our stock rather than developing a local version.

It may be of interest that when I asked Tony Openshaw why the EVA
was more resistant to acid hydrolysis than PVA he said that it is
probably due to the random blocks of ethylene which affect the
stereochemistry of the system.

Stuart M. Welch
Managing Director
Conservation By Design Limited
5 Singer Way
Woburn Road Ind Estate
Kempston
Bedford MK42 7AW
Great Britain
+44 1234 853555
Fax: +44 1234 852334



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                  Conservation DistList Instance 15:18
                  Distributed: Friday, August 17, 2001
                       Message Id: cdl-15-18-001
                                  ***