Patrick Handscombe commented in 110307 MMDigest, "I think you'll find
that some makers today use excellent water soluble cyanoacrylate wood
adhesives for immediate hard joints."

As a violin maker, I would respond, "Never do we do so!"

The belly (front) and back plates are glued to the rib structure using
a weak (runny) hide glue.  This has been convention for about 350 years.
The weak glue allows the plate to be easily removed for repairs with a
blunt parting knife.  The slightly brittle, weak hide glue cracks open
in front of the parting knife.  Sometimes the knife is lubricated with
dry soap.  The plate/rib joint is not acoustically important.

The convention among violin makers is almost always to create a gluing
that is reversible, and only as strong as the specific joint needs to
be, by varying the concentration of the hide glue.  This is how violin
family instruments have survived centuries of repair.  I have not
encountered a colleague who uses cyanoacrylate adhesives anywhere near
a violin.

Patrick's practice of "sealing stack and pneumatic boards first with
water-soluble PVA to achieve a better RTV bond and to completely
protect the original wood of the deck" has a drawback.  By sealing the
original wood with PVA, the repairer confines future repair of the
player to these modern adhesives only.

Animal glues need to penetrate wood.  Violin makers will tend to remove
the old glue of a parted joint with a hot dryish brush, constantly
cleaned in near boiling water and flicked dry.  Hardly a wood fibre is
harmed (mostly, anyway!).

But, that glue joints are reversible is really the overriding and
commendable principle.

Tim Crake
Auckland, New Zealand