Soundboard varnishes: What NOT to use!

[gordon stelter]

Well, Stradivari apparently believed in the "little
resonant spruce cells" for which I will be maligned
for mentioning again (a la American Steel & Wire 1917
transcripts ) because scientific analysis has shown
that he depleted his spruce of resins by soaking it in
barrels of seawater. His varnish probably had little
to do with the legendary tone. 
     I have come to the conclusion that I may have
used a bit too much M.L.Campbells' "Duravar"
conversion varnish on this upright soundboard, and
that is partially the reason for the short sustain in
the upper registers. I was trying to impart new crown
to an old board by spraying this very hard and tough
stuff ( used for bowling alleys )onto a flexed  board
and letting it cure fully while in a brace. I figured
that by adding some material to the cells to
compensate for compression-set I could get a little
crown back in it. I think it worked, too, but I simply
used too much of the stuff. 
     Also, apparently, it outgasses really nasty,
toxic fumes, as I can still smell them in my finishing
shop, from overspray, a year and ahalf after I
sprayed! Make me sick, too. Won't be using THAT again!
     My next board would be just nitrocellulose
lacquer(upright) or a proper rubbing varnish with U.V.
blockers, if a grand.
     Thump


P.S. Could Pianolac be used on a board without
detrimental results due to the water content?


--- David Love <davidlovepianos@earthlink.net> wrote:
> 
> Terry:
> 
> At 3mm thickness, of course, you would expect to
> have an effect on tone. 
> But what about 1 mm?  Or better, at what percent
> thickness would you expect
> the varnish to have an effect on tone and does level
> of hardness have any
> bearing?  I guess I'm calling for speculation.  
> 
> David Love
> davidlovepianos@earthlink.net
> 
> 
> > [Original Message]
> > From: Farrell <mfarrel2@tampabay.rr.com>
> > To: Pianotech <pianotech@ptg.org>
> > Date: 3/19/2003 4:21:00 AM
> > Subject: Re: Soundboard varnishes
> >
> > I have one bit of knowledge that would not be
> speculation. Varnish should
> have no effect on epoxy underneath it - except of
> course for the visual
> effects. I trust your inquiry regarded the integrity
> of the epoxy. And I'll
> go one step further and say that varnish will adhere
> very well to a
> properly prepared epoxy surface (sanded, etc.).
> >
> > Your last statement appears that you are not
> adverse to
> speculation.........so here goes. My understanding
> regarding finish types
> and thickness influencing sound output is this: It
> likely does not matter a
> whole lot what you use, just keep it to a minimum.
> Whatever you use, the
> thinner it is, the more your soundboard will remain
> like a spruce
> soundboard. Put a 3 mm thick coat of polyurethane on
> the board and suddenly
> you have a board whose thickness 25% plastic - you
> don't have just a spruce
> soundboard anymore.
> >
> > One thing that I like about varnish is that proper
> application is very
> thin. Twelve coats can give you a dynamite finish
> with lots of depth. But
> it can look very nice with three coats.
> >
> > Terry Farrell
> >   
> > ----- Original Message ----- 
> > From: "David Love" <davidlovepianos@earthlink.net>
> > To: "Pianotech" <pianotech@ptg.org>
> > Sent: Wednesday, March 19, 2003 2:49 AM
> > Subject: Soundboard varnishes
> >
> >
> > > 
> > > Awhile back we were having a discussion on the
> merits of various kinds
> of varnishes.  I continue to explore the effects of
> varnish on soundboards
> (if any) and have a few questions.  
> > >  
> > > First, what differentiates the type of varnish
> used on violins and
> cellos from the spar varnish often used on pianos. 
> I notice that the
> varnish on violins is quite hard, even brittle,
> whereas spar varnishes are
> typically a bit rubbery (have I answered my own
> question?).  What is the
> composition of violin varnishes, typically--I know,
> for Stradivarius it was
> a secret.  How might this difference effect tone on
> a soundboard.   And, is
> there a reason to select a very hard, even brittle
> finish? 
> > >  
> > > Second, are there potential ill effects from
> putting too heavy a coat
> of varnish  on a board.  Can too heavy a coat of
> rubbery spar varnish
> actually impede sound transmission through the
> board, and how thick would
> it have to be to create a problem.  
> > >  
> > > Third, can varnish effect epoxy underneath it?
> > >  
> > > I would be more interested in experiences and
> side by side comparisons
> than speculations, but please feel free to comment
> either way.
> > >  
> > > Thanks,
> > >  
> > > David Love
> > > davidlovepianos@earthlink.net
> > >  
> > > 
> > _______________________________________________
> > pianotech list info:
> https://www.moypiano.com/resources/#archives
> 
> 
> 
> _______________________________________________
> pianotech list info:
https://www.moypiano.com/resources/#archives


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