Hi All,  I found a rather extensive article about PVA adhesives at
http://nautarch.tamu.edu/crl/conservationmanual/File2.htm 

Apparently, good old Elmer's glue was originally casein based.  That
means that it was derived from a milk protein.  It could have been
counted as a dairy product by the school lunch program.  <Mooooo!>

About 20 years ago Elmer had a change of heart (maybe PC?) and switched
to a PVA emulsion that could be dissolved in a variety of solvents
ranging from MEK to benzene, or water.  Recently they advised that the
only recommended solvent was water.  Could be that they changed the
formula or maybe they just wanted to avoid recommending a more volatile
solvent.  Read the article if you're interested.

Our Castlewood organ kit instructions recommend using PVA glue for
assembly -- primarily yellow glue like Titebond.  But we also include
a warning to let things like pipes dry completely before applying the
shellac.  That's because the shellac is basically alcohol and it can
loosen the glue joint.  We have also suggested an alcohol soak to
loosen parts that were assembled incorrectly, especially if the joint
had been glued recently.  However, if the joint is thin and large, it
is hard to get the alcohol in through the edge so it is much more
difficult to get the solvent to the glue.

I would have a couple concerns (besides authenticity) about using PVA
rather than hide glue.  First, it tends to exhibit cold creep.  Given
enough time, any force (even its own weight) will cause the parts to
move.  Second, I'm not so confident that you can 'wash off' PVA with
a solvent (especially water) as well as you can hide glue. Although it
will loosen enough to release the joint, the result is a soft, sticky
mess that smears around.  Third, PVA will definitely interfere with the
finish, whereas hide glue will not.

Regards,
Craig Smith - in March, from the land of snirt, in upstate New York

[ snirt = "Not quite snow, not quite dirt!" -- Editor (Robbie)