System Three Varnish

[gordon stelter]

Thanks Del,
    You have plenty more knowledge about building
pianos than I do, and I virtually cower in your
virtual presence on most subjects.  However, on this
particular point I must differ.
    Spar varnish is, of course, called that because it
was designed for spars on sailing vessels, which go
through tremendous dimensional changes due to
exposure. It has been around long before anything such
as a "UV blocker" was ever imagined, and contains
long-drying oils such as raw linseed or such which
allow it to remain in a very "rubbery", semi-dried
state for a long period of time, far beyond that
provided by normal plasticizers. ( Which really rather
relate to aromatic hydrocarbon thinned lacquers,
anyway, such as nitrocellulose. Aliphatic solvent
finishes, such as traditional varnishes, generally
have as resins substances which will not dry brittle
for decades in and of themselves. )
     Surely you will agreee that a rubber sheet glued
to a soundboard would be detrimental to conventionally
accepted notions of "good tone"?  And that UV
resistance is hardly a factor we need concern
ourselves with, as a soundboard put in that much
direct sunlight would disintegrate far faster than its
finish  would. ( And anyone who would treat a piano
like that would probably be tone deaf, anyway! )
     Therefore, I believe that the best finish for a
soundboard would be a very hard, moisture resistant
one, such as M.L. Campbell's "Duravar", a 2 part,
catalyzed finish for bowling alleys and such.  I
believe that its combination of rigidity, density and
toughness will help transmit vibrations across the
face of the board rapidly, not absorbing them as heat,
and its imperviousness to humidity will help
everything stay nice and stable. Now, it may be that a
finish that dries truly brittle, such as shellac,
would be even better and I have seen many boards with
this, in fact. But I was looking for a good finish for
an often unheated church, so I chose Duravar.
    Drawback: Its pretty toxic as it cures, emitting
LOADS of formaldehyde fumes, so it needs to be used in
a dedicated structuire away from your general shop.
     I used this on my last restoration, trying to
impart crown to a flattened board by spraying it on
while the board was in a sort of brace keeping it
flexed outward. And I let it cure for 2 months in the
brace.
    As Ron just stated, it is compression we are
trying to defeat in our quest for the "Eternal Crown",
so I am hoping that, by stiffening the outer layers of
cells with this stuff while in an arched sate, I can
help prevent them from compressing and allowing the
board to go flat.
    I believe it was successful, although I did not
take careful measurements prior to disassembly. It has
a TREMENDOUS bass for a Krakauer 50" upright with a
very low tension scale and light ribs, and I believe
it will have a fine treble, too, once I juice the
hammers a bit ( I used a brand I may not be using
again in the future, one which has borne plenty
criticism on this list. Didn't know better. Sorry.
     Respectfully,
     Thump
    
--- Delwin D Fandrich <pianobuilders@olynet.com>
wrote:
> 
> ----- Original Message -----
> From: "gordon stelter" <lclgcnp@yahoo.com>
> To: <davidlovepianos@earthlink.net>; "Pianotech"
> <pianotech@ptg.org>
> Sent: February 28, 2003 9:17 AM
> Subject: Re: System Three Varnish
> 
> 
> > Spar varnish is spar varnish because it remains
> > flexible to cover shrinking and swelling wood in
> > outdoor use. If you wanted to deaden a soundboard
> I
> > can think of no better thing to put on it except,
> > perhaps, a rubber mat.
> >     Respectfully,
> >     Gordon Stelter
> 
> 
> Nope. Spar varnish is called spar varnish because it
> contain UV (ultraviolet
> light) blockers. UV is the death of clear varnish
> and epoxy. As it stated in
> the articles, epoxy must be protected (covered) by
> some kind of finish
> containing UV blockers. Spar varnish is a good
> candidate for this, as is
> some types of lacquer (they must contain UV
> blockers--check with the
> manufacture).
> 
> Nearly all finishes intended for use on wood have a
> certain amount of
> plasticity built into them. Else they would simply
> crack and check like
> crazy as the climates change. Much like the
> varnishes of the early 20th
> century commonly did.
> 
> No, I have not tried System Three Spar Varnish but I
> suppose I should.
> 
> Del
> 
> _______________________________________________
> pianotech list info:
https://www.moypiano.com/resources/#archives


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