Finishing the Inside of Soundbox
John E. Golden
seen have finish applied on the inside of the soundbox. I have heard that
there are a few other luthiers who finish the inside. I am curious to know
the reason Mr. Kohno finished the inside.
Mr. Kevin Hall, Canadian Luthier/Guitar Repairman posted on the Builders
Newsgroup that "In the late 70s Yamaha built a number of very high-end
classical guitars for Canadian classical 'star' Lionna Boyd. Some of those
were varnished in and out, but Ms. Boyd disliked them to the point where
she demanded that the firm pull the backs off and scrape out the finish
within."
What are the advantages and disadvantages of finishing the insides?
I believe that Masaru Kohno, who died in December, 1998, was a very serious
and capable luthier and I am sure he had good reasons for finishing the
insides. I would just like to know what they were.
Regards,
John E. Golden
alcarruth
incidence of cracking due to humidity changes. I have not seen any
proof of this, although, to be sure, it would a tough one to prove
either way.
Usually any inside finish is quite thin, and that would minimize the
useful effect. Any amount of finish is generally thought to be
detrimental to the guitar's sound, particularly on the top, since it
adds weight and (often) damping. Doubling the weight by finishing the
inside would have to be worse for the sound if that's true.
Certainly any buildup of finish on the inside that sufficed to protect
the wood would make later repairs difficult. Glue does not stick well
to finished surfaces, and it would be difficult to scrape away finish
if one wanted to put studs across a crack. For that reason alone I'd
rate it as a bad idea.
Alan Carruth / Luthier
Kevin Hall
"alcarruth" <alca...@aol.com> wrote in message
news:661e4a42-ea38-40df...@k8g2000yqk.googlegroups.com...
Then there's the old woodworkers' point of view that what ever you do to one
side of a wooden panel should be done to the other side in order to minimize
warping, cracking etc.
I've also heard the argument that finishing the inside creates a more
reflective surface to reduce any damping effect of raw wood. Just goes to
show that for every theory there may well be an equal and opposite theory.
;-)
Obviously from a repairmans' standpoint the last thing we want is finish
inside as well as out to make future repairs more difficult. I'd rather
rely on well seasoned wood and careful assembly at a controlled relative
humidity level to keep things stable as opposed to hoping another layer of
finish will keep moisture in and out, but several excellent luthiers do
finish the interior for reasons of their own.
KH
John E. Golden
Although it doesn't sound good, I've heard that some guitar manufacturers
finish the entire soundoard before gluing on the bridge. So, I wonder if
cleats couldn't effectively be glued to a finished soundbox interior.
Regards,
John E. Golden
David Hajicek
"John E. Golden" <johnis...@NOSPAMgmail.com> wrote in message
news:Xns9F49C5D785555jo...@69.16.185.252...
I know Titebond sticks well to Shellac. I would expect HHG to also. But I
haven't tried it.
Dave Hajicek
Chuck Morrison
tension string on the guitar. As I recall, this was using the LMI
white glue. On the positive side, it came off fairly cleanly with only
a small amount of tear out which was easily repaired. A simple repair,
but one I'd rather not have to do.
I used to scrape all the finish off the bridge area for every guitar,
but now I use masking tape and only scrape/sand it minimally to assure
good wood to wood contact.
Chuck Morrison
> >> Alan Carruth / Luthier
>
> > Although it doesn't sound good, I've heard that some guitar manufacturers
> > finish the entire soundoard before gluing on the bridge. So, I wonder if
> > cleats couldn't effectively be glued to a finished soundbox interior.
> te
Kevin Hall
cyanoacrylate adhesive ( Super Glue). They're relying on the adhesion of
their finish ( usually UV cured poly) to hold things together, and it's a
crappy idea. When such joints let go they often bring sections of the
finish with them, turning a normally simple bridge re-glue into a major
touchup headache.
KH
"John E. Golden" <johnis...@NOSPAMgmail.com> wrote in message
news:Xns9F49C5D785555jo...@69.16.185.252...
Nick Odell
<alca...@aol.com> wrote:
>Finishing the inside is thought by it's practitioners to reduce the
>incidence of cracking due to humidity changes. I have not seen any
>proof of this, although, to be sure, it would a tough one to prove
>either way.
many years ago, I had a custom order from a musician who lived in
Brunei and we decided that the instrument was more likely to survive
the extremes in temperature and humidity and potential infestations if
it were completely sealed.
>Usually any inside finish is quite thin, and that would minimize the
>useful effect. Any amount of finish is generally thought to be
>detrimental to the guitar's sound, particularly on the top, since it
>adds weight and (often) damping. Doubling the weight by finishing the
>inside would have to be worse for the sound if that's true.
>
was non-standard in a lot of ways (he was a tiny, thin man with tiny
hands and the instrument was built to suit him) so it was hard to tell
what the effects were. Unfortunately (2) I never heard from him again
after he went back to Brunei so I have no data on what happened to the
instrument or whether it is still being played
>Certainly any buildup of finish on the inside that sufficed to protect
>the wood would make later repairs difficult. Glue does not stick well
>to finished surfaces, and it would be difficult to scrape away finish
>if one wanted to put studs across a crack. For that reason alone I'd
>rate it as a bad idea.
have cracks and splits in need of repair.
This has been a fairly pointless contribution to the thread but it
seemed like a good way of letting you know that my recent silence is
not because I'm lying dead and undiscovered on my workshop floor - or
worse that I've abandoned USENET for Facebook - but because I've been
away from the UK visiting one of Her Majesty's former penal colonies
in the southern hemisphere.
Nick
Father Haskell
> Manufacturers who slap bridges down on the finish generally do so using a
> cyanoacrylate adhesive ( Super Glue). They're relying on the adhesion of
> their finish ( usually UV cured poly) to hold things together, and it's a
> crappy idea. When such joints let go they often bring sections of the
> finish with them, turning a normally simple bridge re-glue into a major
> touchup headache.
CA is the most useful stuff since duct tape, but isn't it brittle
and liable to fail under a sharp impact?
David Hajicek
"Father Haskell" <father...@yahoo.com> wrote in message
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Yes. And sometimes that is used for temporary assy situations. But it can
be pretty strong too. The problem is that with wood, it soaks in (unless
thickened) leaving a dry joint. It also attacks some finishes (all
finishes?).
Dave
Tony Done
It also attacks some finishes (all
finishes?).
Dave
I've used it as a filler for both spray can and catalysed poly, and it will
make a completely seamless bond, at least where I have used it. I repaired
some small dings in my Martin D-16 top (polished catalysed poly) with it,
and literally couldn't find them after a few weeks when the grain had come
back up again after sanding.
Almost OT - Differences in hardness between the finish and the repair can be
an issue, so I remove as much of the filler as possible before sanding. I
use a very sharp 1" chisel, with a bit of masking tape at over the edge at
each end so that the centre of the blade is just above the working surface.
I've also used a Stanley knife blade with tape at each end as a scraper,
you can bend it by pushing in the middle of it with your thumbs to get it
lower if need be.
Tony D
David Hajicek
"Tony Done" <tony...@bigpond.com> wrote in message
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Dave