I haven't worked with lutes for a long time, and should probably drop
off the list - but I like reminiscing <g>). I'll venture an answer, I do
work still work with harps. Wood is never dead until it petrifies, it
always takes in or gives off moisture depending on the environment
(humidity and temperature). If you don't treat it at all it will be more
susceptible to the changes in atmospheric conditions, but if you seal it
then it can't "breathe". I wasn't familiar with the Stand Oil that
Martyn mentions, but just Googled it and see it is a pure linseed oil
heat treated. That fits my criteria. You mention a beeswax concoction, I
am familiar with them from my wood turnings as I make several
"concoctions" for different purposes. The beeswax concoctions at the
simplest are a mixture of pure beeswax and generic mineral oil - but
could be mixed with a vegetable oil (like linseed or tung). The tung
adds color, the linseed doesn't.
Your purpose in treating your sound board (the lute top) is to maintain
its flexibility and sound production. The lute, like the guitar and
violin (each to a greater or lesser extent) produces its sound in
combination with the enclosed body of the instrument. The function of
the sound board is somewhat modified by the nature of the transmission
of string vibrations through a bridge over which the several strings are
in contact with the sound board. That sounds gratuitious, but the harp
that I deal with is quite different. The sound transmission of the harp
is almost entirely from the vibrating strings in air, the function of
the sound board (top), which is under tension from each string, is to
pass the sympathetic vibrations from one string to another by direct
vibration. The bridged instruments, like the lute, separate the sounds
and produce the fullness in the body and top by combining them there.
I could put a sealing finish on a harp sound board (athough I wouldn't,
it would reduce the sound a bit), but not on a bridged instrument. The
sealant stiffens the soundboard and it is a part of the sound in a
bridged instrument.
I think you should treat the sound board (the lute top) on both sides. I
wouldn't use a varnish, it soaks in but hardens. I certainly wouldn't
use a shellac as it is a surface coat and stops the breathing (although
I do use a home made shellac compound with mineral oil for some pieces).
You want something that allows the "living" wood fibers to absorb or
give off the moisture, but not too fast. If you use a pure oil, like the
Stand Oil, you would want to refresh it now and then..
Here is a pure speculation, and I leave it open to suggestions. A gentle
sealant like one of the beeswax (or other wax/oil) concoctions for the
underside of the sound board and a pure oil for the topside. Inhibit the
drying of the internal wood cells through the internal body, but don't
block it. Once the instrument is built you can't change the finish on
the inside. Use an oil on the topside, and reuse it.
Best, Jon
On 1/23/2015 6:59 PM, Paul Daverman wrote:
I am wondering if some of the builders would be gracious enough to
weigh in on their treatment of the lute top. Some say absolutely
nothing should be put on the top. Others say varnish. I believe
Lundberg had given a recipe for a bee's wax concoction. I'm curious if
there is a consensus or standard.
Thanks,
Paul
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