Klarinet Archive - Posting 000158.txt from 1999/02

From: Tony@-----.uk (Tony Pay)
Subj: RE: [kl] Bore Oil (Planas Article)
Date: Thu, 4 Feb 1999 12:27:23 -0500

On Thu, 04 Feb 1999 11:16:47 GMT, I said:

> It does seem to me that he [Roger] has put his finger on the nub of
> Ted's argument, whether you agree with that argument or not.

As a followup to the question of whether Ted's argument is sound, I've
contacted some people experienced in the field. Here is one response.

------------------------------------------------------------------------

Jon Steward, who is technician at Howarths, and who designed the Howarth
clarinet, says that he remembers that Ted's experiment on absorption was
done with a new piece of wood.

Jon's own experience over many years of designing, making and repairing
clarinets and mouthpieces leads him to a different conclusion with
regard to the behaviour of older wood. Exactly what are the changes in
the wood as it ages or is played that might cause this change of
behaviour, he says he isn't qualified to judge. Nor does he know of any
scientific study that has been done on the subject. (But see below.)

The large numbers of clarinets of varying age that he encounters show
quite a variation in their absorption of applied linseed oil. In
particular, clarinets that have cracked externally are often
particularly absorbent internally under the crack. And some older
instruments that come in for repair or overhaul take up a lot of oil --
more than would be explained by the very small penetration described by
Ted. Exactly how much oil, seems to be related to both age and history:
older and/or more heavily played instruments tend to be more absorbent.
Jon says he hasn't undertaken a detailed quantative analysis, however,
or kept careful records, to support this correlation.

Based on the principle that permeability to oil is a likely indicator of
undesirable permeability to water, and that a thin layer of wood
containing oxidised oil is some defence against the entry of water, he
has always recommended lightly oiling the bore of an instrument
periodically, (say, once every six months), and suggested that if it
takes up oil overnight, you repeat the process until it doesn't. You
can tell whether the oil has been absorbed by the appearance of the
surface of the wood: unabsorbed oil is visible as a shiny coat, whilst
absorbed oil leaves the wood its normal matte surface.

As has been pointed out previously in this thread, the entry of water
can have the effect of changing the dimensions of the bore: in
particular, the top of the left hand joint may gradually enlarge, with
undesirable effects both on tuning and response. (John suggest this
particular change may be a factor in the phenomenon of instruments being
perceived by some players to 'blow out' after a few years.) Ensuring
that the oiled layer is maintained helps to avoid this.

Jon agrees with Steve that the oil originally left in the surface layer
when the instruments leave the factory is gradually leached out by
moisture and swabbing, and that it is best replaced from time to time.

Though he hasn't done the relevant tests (not being a wood chemist, as I
said above), he also speculates that other substances may be leached out
of the wood, and that it is this sort of change, including possibly
cellular damage, that contributes to increased absorbency. If anyone
knows of any detailed study of this, he would be very interested to hear
about it.

Anyhow, be that as it may, his experience is that deeper penetration of
older wood by oil is established, contra Planas.

-------------------------------------------------------------------------

One response to this is to continue to wonder both whether the increased
absorbency is due to the sort of damage that Jon speculates about, and
also whether in mild cases it might be completely repaired by feeding
oil into the wood.

Tony
--
_________ Tony Pay
|ony:-) 79 Southmoor Rd Tony@-----.uk
| |ay Oxford OX2 6RE GMN family artist: www.gmn.com
tel/fax 01865 553339

Believing Truth is staring at the sun
Which but destroys the power that could perceive.

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