Klarinet Archive - Posting 000114.txt from 2004/01

From: "Forest Aten" <forestaten@-----.net>
Subj: Re: [kl] Cracks, cracks
Date: Sun, 4 Jan 2004 12:37:26 -0500

The warming that Sue mentions is one factor, but a bigger one is moisture.
An illustration is that the huge stones for the Egyptian pyramids were split
by forcing wedges of wood into small cracks then soaking the wood with
water. OK it was a different wood and the clarinet woods are less permeable,
but a warm wet clarinet will definitely be trying to expand from the inside
and exterting quite large forces.

This has no counterpart in a violin. In the violin, it is important to
preserve the vibration characteristics of the wooden parts, which as Tony
and others point out is a second order effect on the clarinet (not zero
effect, but small). So the aim on the violin is to make the repair strong
enough to stand the forces of the strings without altering the vibration
characteristics. Since glues are in general at least as strong as the woods
used in string instruments, wood/glue repairs are ideal in that case.

Clarinets have bigger crack-opening forces and the preservation of the bore
shape to a fraction of a millimetre is also most important. I would support
the pinners over the supergluers.

I am very interested in the carbon fiber banding method, which also seems
appropriate. Anyone know where suitable supplies can be had?

Keith Bowen
<not a pro repairman, but a materials science professor>
-----------------------------------------------------------

Keith,

Carbon fiber, as you know, is not very elastic...but very strong. I believe
that many of the good repair supply vendors have the carbon fiber thread
available. I've seen carbon fiber bands done with such finesse and
craftsmanship, that it is almost impossible to find the band. Even when
looking carefully at the clarinet.

The first time I observed this process was in the Libertyville distribution
point for Buffet instruments (now in California). Francois Kloc introduced
me to his head technician on one of my trips to Libertyville. He was in the
process of repairing a local professional player's clarinet using the carbon
thread. I've seen this technique used several times now. Several repair
people tell me that it works very well on stubborn cracks that resist
successful pinning.

Forest Aten

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