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Re: Adhesive and tyvek



Subject: Adhesive and tyvek

>That recent thread re: tyvek inspired me to cut a mailing envelope apart
>to do a little experimenting. I didn't get far when I found that PVA
>doesn't adhere it to paper. I was able to peel the tyvek right off the
>paper sheet after the PVA had dried.

     The terms "Tyvek"  and "PVA" represent not single products but families
of products.  When different parties are discussing their unique experiences
regarding these particular products chances are that apples are being compared
to oranges unless the references are specific as to the type of tyvek or the
specific brand and product description of the PVA used.

   Tyvek comes in basic flavors,  Types 14 and 16 seem to be manufactured as
cloth substitutes and are used in disposable work clothes and the like.  When
I ordered "Tyvek" (with no further specifics) from Gaylord several year back
this is what I received (not what I wanted).  The type 16 is perforated, I
suppose, to make it more breathable. Type 10 is manufactured as a paper
substitute and is used in envelopes and the like.  All three types come in a
variety of thicknesses and finishes.  My guess is that when tyvek is processed
into a finished product, like envelopes, it acquires different characteristics
because it has often been printed on and, in some cases, seems to have been
coated, possibly to increase water resistance.    Unfortunately, the agents
you buy your tyvek from do not alway have the type and product number
available  (Gaylord for example).  Where you buy your tyvek probably
determines what you receive.  If you buy from a paper supplier (like Alling
and Cory) you most likely will end up with type 10.

   That said, I use a 6 mil Type 10 (25" x 38" sheets)  for my bookbinding
needs.  This seems to be a stock item with the paper distributors I have dealt
with.  I don't believe there is much use for the Types 14 and 16 in
bookbinding as they tend to delaminate fairly easily under stress.

   Once you select the proper tyvek you still have to select the right glue.
The term PVA describes a family of glues that vary greatly in actual working
properties and adhesive properties.   What each of these glues have in common
is that the manufacturer starts with basic PVA .  From this initial starting
point anything can happen as plasticizers, tackifiers and a wide variety of
other compounds are added in varying quantities and blends to produce very
different glues, all described as PVAs.  Chances are excellent that there is
the right PVA for most any task, but there is probably also the wrong PVA for
many tasks.    The right PVA is not only determined by the substrates to be
glued but the types of stress the glue joint will be subjected to.

   Buying the right PVA and comparing notes on what two people believe is the
same PVA is further complicated when you buy your PVA from a third party
distributor (like Gaylord, Bro Dart, University Products...) who put their own
labels on the glue they sell.  The PVA you buy in one year may not be the same
PVA you buy the next year as these distributors may change manufacturers and
formulations without changing the product name.  The solution would be to
encourage these distributors to sell their PVAs under the manufacturer's name
and product number rather than as re-labeled, heaven-knows-where-it-came-from
products.   Purchasing an appropriate PVA has been further complicated by our
own profession which insists on references such and "acid free,"  "pH neutral"
 and "reversible" when shopping for a PVA.  These are all useful references
but have nothing to do with the actual working qualites of the PVA in
question.  These working qualities range from how easy is it to work (are we
brushing it, rolling it, applying it with a glue machine) to how well does it
work with different materials.  Does the application require a stiff film or
an elastic film?  Does it require a thin film or a thick film?  An so on.

     I return to the basic question.  I glue my type 10 tyvek with Wisdom
Adhesive's R172DT.  This is a relatively spreadable, highly elastic PVA that
seems to work well with difficult substrates such as tyvek.

    My apologies for rambling.  The original query hit one of my hot
buttons.

                                                         Pete Jermann


Pete Jermann
Preservation Officer/Bookbinder
Friedsam Memorial Library
St. Bonaventure University
St. Bonaventure, NY 14778
Tel. (716) 375-2324


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