Re: poly vs. nitro clear coat - age

RichL wrote:
On Mar 29, 8:10 pm, The Repair Guy <repairguy1...@xxxxxxxxx> wrote:
Dave Van <daveYOUR...@xxxxxxxxxxxxxxx> wrote:
The Repair Guy wrote:
Jim <a...@xxxxxxxxxxxxxxxxx> wrote:
A true test would have to use the SAME guitar
(finish, test, strip, finish, test), played by a freakin'
robot (to make sure all notes are hit the same
way).
Easier way: ignore wood, use artificial body.
If you're only testing for differences in finish,
the body material shouldn't matter as long as
it's uniform (well... uniform compared to wood,
anyway).
But the argument is about the impact that finish
has on the wood.
My mistake. I thought it was about the effect
finish has on a guitar's sound. Maybe I mixed
up threads...

The Repair Guy
repairguy1993 dot netfirms dot com

If there is any effect of the finish on tone at all, it would matter
whether the finish is on wood or something else. From the point of
view of physics, what matters is the difference between the elastic
properties of the two materials. (This will bore most folks, but I'll
continue anyway....) With no finish at all, the wood surface is
"free" to vibrate any way it wants to. In physics, it's called a free-
surface boundary condition. Now, if you had a finish material with
elastic properties and sound speed identical to wood, there would be
no practical difference, i.e., a sound wave wouldn't even "see" the
finish as a different material, and again the surface would be free to
vibrate, as in the just-wood case. It's analagous to a perfect
impedance match in electronics.

Any difference in tone therefore results from different elastic
properties. The sound wave sees the difference and partially reflects
from the boundary between the wood and the finish. The other part of
the sound wave travels to the finish surface and reflects back. The
two reflected waves can interfere (in principle) and change the
sound. The other effect the finish has is, in essence, changing the
boundary condition at the surface, because the finish material can be
either stiffer or more compliant than the wood. The thinner the
finish, the less all this matters, however. In reality, such effects
are very small, especially for an electric, unless the finish is
"gooped" on.

If the thickness of the finish is large enough for all this to matter
significantly, then the conclusion is that if you change the wood to a
different material, the results will change. With the finishes on
good solid-body guitars, however, this is not the case; it's just too
darn thin to matter in the first place.

Y'all can wake up now, I'm done.




GOD THAT WAS BORING!!!
.