System Three Varnish

[gordon stelter]

Thanks Del,
    After a good night's rest I realize we're "both
right". I'm right about the original definition of
spar varnish as a "Long-Oil" varnish, and you're
probably right that the new definition is "UV
resistant", although it must retain some of those
"Long-Oil" qualities of abrasion resistance and
flexibility, regardlesss of how it is formulated these
day. (Don't ever try to rub out a spar varnish
finish!)
And you are also right that, in the thicknesses used
in soundboard work, it probably doesn't matter much
WHAT the finish is, tonally. 
     HOWEVER, I would still prefer a finish which
will, in my opinion, carry the vibrations away from
the bridge rapidly while absorbing them least, to
excite every portion of the board. And one which
really seals the board against humidity, as much as
possible. I am encouraged by my 100 year old Knabes,
for example, which sound great with a very heavy
finish coat on the boards, and still no cracks! Now,
epoxy will certainly do this, as it is dense,
relatively rigid and virtually impervious to
moistuure. But, if you are trying to create rigidity,
would you not want the stiffest (when cured) and least
viscous epoxy you can find, as long as it is not thin
due to solvent thinners? And isn't Epotek 301 the best
by this criteria? Wouldn't you want it to permeate the
board as much as possible? I'm sorry to say that I
have not read your articles yet.But I will, ASAP.
     Also, regarding the following:

 I have
> > used varnishes for years on soundboards, usually
over a shellac undercoat
> > without detriment...... 

The use of varnish ( which dries by oxidation,i.e.
grabbing molecules from the air ) over shellac, which
dries purely by evaporation of solvent, is the #1
cause of "alligatoring", for the varnish expands as it
cures, while the shellac shrinks. 

And..........
>
> David,
>
> As I said earlier, I've not used System Three
varnish. But the compatibility
> issue may be a valid one. 


I'd use a topcaot with an aromatic hydrocarbon
solvent, as this will "bite" into the epoxy a little
for a good bond. In other words, a lacquer, and with
U.V. resistance.
    Thump


 

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