Hot melt adhesives

Mark Aronson <mark.aronson<-a t->yale< . >edu> asks:

>Is anyone familiar with the properties of Hot Melt Glues?  I need an
>archival hot melt glue to assemble acid free storage boxes.  In
>addition to having a long use the material should not contain
>components that might offgas and tarnish silver.

I've done a fair amount of experimenting with hot melt glues, the
type you shoot out of a hot glue gun. Several points to consider off
the bat--there are no standards that I know of across the board for
hot glues--every manufacturer will have their own patented formula.
Unless you are talking about heated animal hide glue, I don't think
there's been that much study in the field of conservation of hot
melt glues, certainly not as much as there has been on PVA. In fact,
I wonder, for this application, why one would not want to use PVA?
Hot melt glue has many structural disadvantages, only small amounts
of it can be ejected at a time (for the gun can only get so much
hot), and hot glue melts fast once it hits the air. Even if there
are no offgassing issues (and I suspect there probably are), hot
melt glue applied using a gun, I would think, would only be
efficacious in the housing of small octavo books, or for any
application needing no more than about 5 teaspoons of adhesive. PVA
also spreads very thin, and does not compromise the media as much as
hot melt glues, which can often burn into the surface of a board.

It is only advantageous, in my humble opinion, to use hot melt glues
when you are adhering either pieces of ethafoam or plastic-based
media. If you need to adhere a plastic product, keep in mind that
roughing up a smooth surface will aid the adhesion process. Also,
one colleague of mine suggests some forms of silicon based adhesives
as a safe alternative, such as those recommended for use in
aquariums (relatively inert once dry).

George Leake
taliesin<-a t->mail< . >utexas< . >edu
Harry Ransom Humanities Research Center
UT Austin

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                  Conservation DistList Instance 11:6
                  Distributed: Wednesday, July 2, 1997
                        Message Id: cdl-11-6-002
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