Klarinet Archive - Posting 000710.txt from 1999/12

From: Keith <100012.1302@-----.com>
Subj: [kl] klarinet Digest 20 Dec 1999 09:15:00 -0000 Issue 1918
Date: Tue, 21 Dec 1999 01:54:56 -0500

Jennifer H. Jones, wrote
>As the bore expands with rising
humidity/temperature I would expect it to expand in all directions,
including
towards the crack, thus causing it to close. At the same time, wouldn't
the
material used to fill the crack expand and force the crack open more? =

No, it isn't very intuitive, but if something with a hole in it expands,
the hole gets bigger not smaller!
If the thermal/humidity expansion coefficients of the filler are the same=

as that of the wood, then =

there is no additional stress on the crack. Fillers would usually have
smaller coefficients than wood,
so would not tend to split the wood further (but might leak if not proper=
ly
done.

>Considering cracks are measured in microns, it doesn't seem possible to
control
the temperature/humidity precisely enough to prevent the above from
occuring
and still play the instrument. =

>I haven't had any personal experience with repaired cracks so I would
appreciate a knowledgeable person's input.

I had a Selmer bass clarinet which developed a Grand Canyon of a crack,
measured almost in mm. It was pinned and filled almost invisibly by Bria=
n
Ackermann
and I played it for over ten years with no problems.

I probably wouldn't BUY a clarinet with a repaired crack unless I knew wh=
o
repaired it!

Keith Bowen

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