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Subject: Beva film

Beva film

From: Laszlo Cser <laszlo>
Date: Thursday, November 19, 1998
Barbara Appelbaum <aandh [at] idt__net> writes

>I do not often use Beva, but I am testing it now for a very strange
>treatment, and find the smell is driving me nuts.  I have been using
>the solution of 371.  Does anyone have experience in using Beva film
>instead, and is the smell problem substantially reduced?  Does
>anyone know what the smell is? ...

There has been some discussion on the list regarding  BEVA Film and
there are a couple  of points that may be addressed (some of which
were initially sent to Barbara directly).

It would seem that there are possibly three categories of smells
that are being discussed: the smell referring to the actual solvent
prior to and during handling (solution), the residual volatilizing
of the solvent after application, and the ambient or inherent odor
of the resins (dried solution and film).

In the first instance, good and adequate ventilation is absolutely
necessary when working with the solution.  The solvents used in the
manufacture of BEVA 371 in the US are heptane and toluene, and
health issues should be addressed by appropriate and adequate safety
precautions during handling and  application procedures.  Mr. Galea
in his contribution of the November 13th refers to benzene as one of
the solvents used in the formulation of BEVA 371 Solution.  However,
it must be clarified that it is not benzene (or benzol ) that is
used, which is highly toxic.  Rather it is benzine, or naphtha (VM&P
[varnish makers & painters]  naphtha), which nevertheless requires
proper ventilation and safe handling.

In the second instance, solvent evaporation/retention and residual
odors following application are dependent on a number of factors:
thickness of the resin application, method of application
(brushed/rolled/sprayed), absorbency of the  substrate, single or
multiple layers and duration between coats, and atmospheric
conditions.  Generally, a minimum of 12 hours should be allowed for
the solvents to  evaporate from a moderate coating on an absorbent
substrate like linen or cotton.  If rolled out onto Mylar, a thin
coat will dry  in 15 minutes or less.  (In Barbara's case, it should
be noted that the application of a solvent onto leather, be it water
or a hydrocarbon, may release pungent odours that could be caused by
rancid oils, old sweat, or any variety of other accumulation and
deterioration products.)  Beva Film is totally solvent free and is
recommended for use where direct solvent contact with an object or
surface is contraindicated, or when ventilation and odors are
problematic.  It can be manipulated in numerous ways depending on
the  indications  of the treatment.  The Film and the Solution are
identical in resin composition.

The third instance to which the query alludes is the ambient smell
of the resins.  Beva is composed of  ethylene vinyl acetate,  a
copolymer, cyclohexanone resin, a tackifier, and a small amount of
oil-free paraffin. Each of these has its own characteristic odor
which may be slight but nevertheless detectable.  This is so with
just about every material, organic or synthetic. Sensitivity to
these odors varies from person to person, as do any subjective likes
and dislikes.   When we sit in a new car and smell fresh new vinyl
it is appealing to some.  Others dislike the smell or thought of
plastics in their new cars, and will buy ones made with more leather
than plastics inside, having more mechanical joinery with less glues
so that the  smell is more attractive to them.

Having said that, a good snort from a can of freshly opened tennis
balls, a new beach ball, or a pair of running shoes (before they're
used)--all have characteristic vinyl odours that are not at all
unpleasant to many.

Laszlo Cser
Restorart Inc.
23 Morrow Ave.
Toronto, Canada
M6R 2H9
Fax: 416-532-6829

                  Conservation DistList Instance 12:46
                 Distributed: Monday, November 23, 1998
                       Message Id: cdl-12-46-001
Received on Thursday, 19 November, 1998

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