Klarinet Archive - Posting 000114.txt from 1996/11

From: Roger Shilcock
Subj: Re: Mouthpiece Mania/freezing (fwd)
Date: Tue, 5 Nov 1996 10:55:06 -0500

---------- Forwarded message ----------
Date: Tue, 5 Nov 1996 08:50:16 -0500
From: Joie Canada , Jcanada713@-----.UK>
Subject: Re: Mouthpiece Mania/freezing

As a metal smith (non-ferrous) I can say that annealing (heating metals to
red hot and cooling without quenching) removes stresses established in the
metal by forming (hammering, stamping or drawing) by causing the molecules to
move around with more activity (the heating process) and to settle in even
distribution patterns (the slow cooling) which removes the irregular
distribution caused by the forming processes.

Forming processes compress the distance between some of the molecules and
stretch the distance between others. Forming processes, if carried on too
long without annealing, will cause brittleness in the metal since the
compressed parts are very dense and the stretched parts are not, making them
weaker. To make non-ferrous metals strong but stiff, the balence between
annealing and forming has to be done carefully. Freshly annealed metals
which are not planished, or lightly and smoothly hammered all over to
compress them evenly and make them stiff, are very soft.

Since mouthpieces are not made of metal as a rule, and would melt, burn or
explode if heated to red hot, the process does not apply. Freezing merely
slows the movement of molecules temporarily , it does not change their
configuration unless carried to a degree (which may occur at liquid nitrogen
temperatures) that causes expansion rather than contraction (water swells
when frozen to a certain point which is why the ice cubes you make in the
refrigerator swell in the middle) Water is unusual in that it does swell
after going from liquid to solid form. Most materials shrink when cooled
which allows molded plastics, metals and other materials to be removed from
their molds easily, since the liquid material that was poured into the mold
gets slightly smaller as it cools and hardens into a solid, freeing it from
the mold.

Cooling an already molded material extremely (liquid nitrogen) causes it to
shrink while it is cool, but it expands again when it is re-warmed to room
temperature. The cooling may cause some compression of the structure, but
the molecules become much less active in relation to each other. They may
re-establish some of their electrochemical relationships with their molecular
neighbors as they are re-warmed, but unless the material has unusual
characteristics, it is the re-warming part of the process that may have an
effect on structure rather than the cooling process.

I am not a plastics expert--just metals. The increased density (shrinking)
of most materials when supercooled is lost when they are re-warmed, hence I
doubt that a mouthpiece would be significantly affected by supercooling. If
a denser material of mouthpiece is desired, and one with less chance of being
changed in configuration by the beating of the reed on the bars, I suggest
crystal mouthpieces--and don't put them in the freezer! Glass (crystal) is
not a true solid--it is a supercooled liquid--which is why very old windows
are slightly thicker at the bottom than at the top--they "ooze" very slowly
under the influence of gravity. Rock crystal mouthpieces (carved from quartz
crystal rather than molded of glass) are another matter--a very expensive
other matter!

Personally, if I don't like a mouthpiece and I have had it looked to by a
good tech who knows re-facing, etc, I ditch it and get a new one. They do
wear out--especially the plastic and hard rubber kind.

Sorry for the length of this message but someone asked!

Joie

At last - an expert on this. SOme metals, notably tin, and (I think)
antimony, change their configuration at temperatures which are not all
that low so as to lose their obviously metallic properties. Tin has a
transition temperature for this of 13.2 Celsius (approx.), so
theoretically a cool room could cause tin to crumble. Usually, the change
does not occur unless the metal is seeded with the stable form, or at
Russian winter-type temperatures - hence the story that Napoleon's army
lost not only the campaign in Russia but also their clothes, as their tin
buttons disintegrated.
I don't know whether these tendencies of some metals affect their alloys;
this would depend on how much of them were present, and how close the
structures in which they were present were to the structures of the pure
metals.
If rubber is cooled to liquid nitrogen temperatures, then it becomes
inelastic and extremely brittle - totally useless for mouthpieces, I would
have thought. (I have seen this demonstrated).
Roger Shilcock

   
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