Klarinet Archive - Posting 000834.txt from 1998/09

From: Michael Cogswell <Michael_Cogswell@-----.com>
Subj: RE: [kl] Pitch standard confusion
Date: Wed, 23 Sep 1998 11:47:06 -0400

The wood conducts heat so that the entire cylinder gets warmer, hence the
entire cylinder expands. Significant differences between the internal bore
temperature and external surface temperature would create a lot of stress,
potentially enough to crack the wood. Hence the suggestions that you warm
your cold clarinet before blowing that nice warm, moist air through it.

I suppose it is theoretically possible to externally cool the outside
surface of the cylinder to maintain its temperature and prevent expansion.
That would force the wood to compress as the interior expanded. It might
even cause a temporary reduction in the bore diameter, until the wood split
like a frozen coke can.

In the real world, the whole clarinet gets warmer and the bore gets bigger.

MikeC

-----Original Message-----
From: Edwin V. Lacy [mailto:el2@-----.edu]
Subject: RE: [kl] Pitch standard confusion

On Mon, 21 Sep 1998, Michael Cogswell wrote:

> Actually, when a cylinder expands the bore gets bigger not smaller. The
> expansion causes an increase in the circumference, hence the inside
> diameter increases. However, it is relatively moot. I'm in agreement
> with the argument that the change in air density is much more
> significant.

I've never measured it myself, but I have it on what I consider to be good
authority, namely a prominent instrument manufacturer, that the above
assertion is incorrect. AS I understand it, the integrity of the external
circumference prevents the material from expanding in that direction.
Thus, the only way for the material to move is inward, thus causing the
bore to become smaller.

Ed Lacy
el2@-----.edu

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