Question about high gloss finishes

[William Bailer]

On Mon, 5 Aug 1996, Jim Kinnear wrote:

> Re the query about breathing wood... are we sure it needs to breath??
> I'm waiting in breathless anticipation for the collected wisdom.....
> Jim   :=}

Very good question!  I believe the word "breath" (with a "long e") has
sometimes been used in reference to wood because of the need of wet wood
to dry out.  If wood were never excessively wet, it would not need to
breath, and if restrained from breathing, would not get wet!  In any
case, sealing wood from the effects of the changes of humidity keeps it
more stable.  Some of the best preserved specimens of fine wood
craftsmanship are from the very stable environments of ancient Egyptian
tombs--  it looks almost new--  still perfect joints.  A water-tight
finish on wood reduces the extremes of humidity that wood is exposed to,
and the stresses on joints (and warpage) are greatly reduced--  an
obvious advantage to a piano.

Finishes vary greatly in their perviousness to gaseous h2o ("water
vapor", or "humidity")-- in other words-- how thick or glossy it looks
is not an indication of how well it blocks the passage of water vapor. I
do not have technical information on these properties, but based on
general chemical properties, I would guess that polyester is very good
in this regard.  Oil based finishes not as good, but better than shellac
or laquer.  I suspect shellac is the worst in this regard-- it
immediately absorbs water on contact (you see it as "rings" from a wet
glass).

I would like to put the FUNCTIONALLY BEST finish on a soundboard,
without regard to subtlties in appearance.  It may mean less chance of
cracking, less breakdown of the internal structure of the wood, and
better tuning stability!

I would like to hear if anyone knows more about this subject, or knows
of references which contain detailed specs on finishes and their
qualities as a water vapor barrier.  Anybody out there with a background
in organic chemistry?  Anybody made observations that may be relevant?

Bill Bailer

\\\  William Bailer ("Bill")
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