Telling plastique keytops where to stick it

[Larry Fisher]

I also use PVCE glue and have for the last couple of years (3-4 anyway) and
have been quite pleased with the results.  I used to use contact cement as
did thousands of other people.  I found some of that stuff failed totally
after a while, anything from a few years to 20 + years later.  I got to
looking at the underside of the old keytops, the ones with contact cement on
them, and I found small divots, small dimples that I assumed were created by
the reaction of the contact cement with the keytop material (poly styrene,
poly propolene, poly carbonal, poly n' ester).  If an adhesive used is
reacting in a destructive way with the material it's holding, it makes sense
that the bond will be compromised eventually.  I started using PVCE glue one
day because it held a beer bottle to a piece of copper clad so well that I
figgered if it works that nice on two very odd surfaces, I should give
plastic to wood a try.

Wood swells and contracts at a much more active level than plastique.  When
PVCE glue is dry, it's quite rubbery.  This allows the keytop to be at odds
with the wood it's glued to, hence the glue joint lasts longer.  During the
process of glueing the keytops on, glue gets on your fingers and your
fingerprint is imprinted on the keytop.  With contact cement, that imprint
is a chore to remove even with a buffing wheel.  With PVCE glue, you can
wipe it off while it's wet or after it dries, either way it leaves no record
of it's position on the key.  This tells me that the glue is not reacting
with the keytop in the manner that contact cement would.

After I've installed all 52 keytops, during room temperature weather, I can
go back to key #1 and start filing the edges and pealing off the excess
glue.  I use keytops from Vegias Ventures and for spot replacements I use
whatever looks the best (Baldwin, Samick, Schaff, Yamaha, Kawai, Young
Chang, etc) and PVCE glue.  When I do spot replacements in the home, I tell
the customer not to play the piano for a few hours and not to pull up on the
key for a day or two.  In some cases I've had to put the wrong size key on,
for a temporary fix until the right key comes in.  The removal of the
freshly glued on key, fully bonded weeks later, removes from the key quite
nicely with a minimal amount of surface prep to glue on the proper keytop.

One final note, for those of you with unheated work spaces, this glue will
not set right in chilly weather.  The warmer it is the faster it sets.  Room
temps are the best, it's heavy bodied and sets the nicest.  Warm temps
generate a glue that's runny and harder to deal with.  Cool temps makes the
glue set up really slow or in some cases not at all.  I'm not sure about
freeze/thaw stability however, I've had a gallon jug of it in an unheated
shop area and have never had any problems with it.  (Things rarely freeze in
that area)  I've had a small squeeze bottle of it in my car from time to
time and have never had any trouble with it performing the way I want after
it gets to be room temp.   (temp changes in a car can be brutal)

Lar

                           Larry Fisher RPT, Metro Portland, Oregon's
                  Factory Preferred Installer for MSR/PianoDisc Products
                       phone 360-256-2999 or email larryf@pacifier.com
                  http://pacifier.com/~larryf/homepage.html (revised 5/96)
                         Beau Dahnker pianos work best under water