Ethanol soluble adhesives

Deborah Howe <d-howe [at] nwu__edu> writes

>We have recently received many items from the elections in South
>Africa. Among them are some posters mounted to masonite.
>...
>Then we used ethanol and they lifted off
>beautifully.  There isn't any sticky residue and I was wondering what
>could have been used as the mounting material?

Have you considered shellac, especially shellac-based dry-mounting
medium?  Shellac adhesives are still used in many locales and was
the basis of most photo dry-mounting tissue until the advent of
resin-coated photo papers.  Relatively fresh shellac is readily
soluble in methanol or even ethanol.  After the solvent evaporates,
the surface will not remain tacky.  Shellac is softened and hydrated
by both water and steam, but in your context, neither agent is
likely to have caused detachment.

    **** Moderator's comments: For interesting historical background
    see Stephanie Watkins's Origins and Development of Dry Mounting,
    in the Book and Paper Group Annual, v. 12 (available in
    Conservation OnLine:
http://palimpsest.stanford.edu/byorg/aic/bpg/annual/v12/watkins/watkins.html

In addition to shellac, casein adhesives can be alcohol soluble as
are polyvinyl alcohol (most grades are water soluble also, however),
polyvinyl butyral, some PVA formulations, and most natural plant
resins including pine resins and damar.  I am sure that there are
many other possible resins or mixtures as well.

Geoffrey Brown
Curator of Conservation
Kelsey Museum
University of Michigan

                                  ***
                  Conservation DistList Instance 9:49
                Distributed: Thursday, December 14, 1995
                        Message Id: cdl-9-49-005
                                  ***