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Subject: BEVA 371

BEVA 371

From: Irene F. Karsten <ikarsten>
Date: Thursday, February 1, 2001
I am writing in response to the message posted by Chantal Bernicky
on the yellowing of Beva 371.  I would like to share my experience
on the yellowing of Lascaux Hot-seal Adhesive 371, a product similar
to Beva 371. This adhesive contained ethylene-vinyl acetate
copolymer, ketone resin N, and paraffin as a 20% solution in
toluene/1,1,1 trichlorethane.  The product was a spray adhesive
propelled by propane/butane gas. This adhesive is no longer
available.

I tested the effects of light ageing on textile laminates formed
using this adhesive as well as samples of silk and polyester
crepeline sprayed with this adhesive in the same manner as those
heat-sealed to the solid fabric.  These samples were exposed to
xenon arc radiation (similar to very intense sunlight through window
glass) for 86 and 172 hours.  Yellowing was just barely visible on
coated polyester crepeline after 86 hours of exposure, an effect
that must have been due to the adhesive since the same fabric coated
with Appretan MB extra (an vinyl acetate-dibutyl maleate dispersion)
or not coated at all exhibited no yellowing.  The adhesive coating
on these fabrics was very thin and equivalent to that used in
textile treatments.

There was some evidence, although not conclusive, that the adhesive
did not yellow when covered with a fine translucent silk fabric. The
exact relationship between the intense ageing conditions used and
the effects of normal exposure to light, especially where UV
radiation is excluded, is not known. Whether the yellowing in this
adhesive is equivalent to that observed in Beva 371 by Jane Down at
the Canadian Conservation Institute is also not known.

The full text of my research including the results on yellowing can
be found in my thesis, The Light Stability of Silk Adhered to Sheer
Silk and Polyester Backing Fabrics with Poly(vinyl acetate)
Copolymer Adhesives (1998). Copies can be found in the following
library collections: University of Alberta, Canadian Conservation
Institute, and the Winchester School of Art.

Another reference that documents the yellowing of Beva 371 film upon
light ageing is: David Horton-James, Sue Walston and Steven Zounis.
Evaluation of the stability, appearance and performance of resins
for the adhesion of flaking paint on ethnographic objects.  Studies
in Conservation, 36 1991-203-221

I hope this information is useful.

Irene Karsten
Doctoral Student in Textile Conservation
Department of Human Ecology
3-02 Human Ecology Building
University of Alberta
Edmonton, Alberta
Canada  T6G 2N1
780-492-5385
Fax: 780-492-4821


                                  ***
                  Conservation DistList Instance 14:42
                 Distributed: Monday, February 5, 2001
                       Message Id: cdl-14-42-001
                                  ***
Received on Thursday, 1 February, 2001

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