Soundboard varnishes

[Gerald Posey]

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  ----- Original Message -----=20
  From: David Love=20
  To: Pianotech=20
  Sent: Wednesday, March 19, 2003 1:49 AM
  Subject: Soundboard varnishes



  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?=20

  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. =20

  Third, can varnish effect epoxy underneath it?      =20

  I'll take this one, since I am a violin maker.  Violins usually have =
one of two kinds of varnish, spirit or oil.  The discussions of the =
merits of each have been going on for hundreds of years.  Spirit varnish =
is alcohol soluble and infinitly short since all the solvent evaporates. =
 I'll concentrate on oil varnish because I prefer it.   Varnishes are =
classified as short or long depending on oil content. Less oil, more =
resin is shorter.  Short oil varnishes are harder and polish out better. =
 There is an infinite range of hardnesses depending on this ratio.  Also =
 oil varnishes can use synthetic or natural resins.  Violin makers =
prefer natural resins, (Since this is obviously what the early makers =
used).  Many violin makers experiment with making their own varnish.  =
Entire books have been written on this subject.   Violin varnish may use =
any of dozens of natural resins, any of several drying oils ( walnut, =
tung, linseed), and sometimes metallic driers.  Violin makers discussing =
varnish is similar to piano techs discussing temperments.

  Too much varnish on a violin is akin to wrapping it tightly in a coat =
of leather.  It dampens the vibrations.  But some damping is good.  How =
much is good?..... Who knows?.  If I could achieve depth of color in two =
thin coats (rubbed out) I would be satisfied.

  Epoxy is frowned upon in violin making, so I can't say how varnish =
affects it.  What does react with dried epoxy?  Linseed oil and resin =
don't harm hide glue.

  I hope this helps, it's  a deep subject.  If there are any questions =
I'll try to answer them.
  Gerald

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