FW: [Dixielandjazz] Re: Cryogenic treatment for brass

[Hal Vickery]

You've got more credentials than I have since I'm just a chemistry teacher,
but since I was in high school back in the mid '60s, I've seen a number of
demonstrations of metals being put into liquid nitrogen.  Never have I heard
any claims from those performing the demonstrations that cooling the metals
would temper them.  Heat is also the only method I'm aware of.

Hal Vickery

-----Original Message-----
From: dixielandjazz-bounces at ml.islandnet.com
[mailto:dixielandjazz-bounces at ml.islandnet.com] On Behalf Of Robert Smith
Sent: Sunday, September 25, 2005 9:47 AM
To: Dixieland Jazz
Subject: [Dixielandjazz] Re: Cryogenic treatment for brass

As a metallurgist I regard cryogenic treatment as highly unlikely to relieve
any residual stress in any metals or alloys. Sress-relieving ('tempering')
is done by increasing the temperature. Room temperature also relieves
residual stresses, but usually takes a long time (depending on the metal or
alloy). Lead for example tempers rapidly at room temperature, whereas brass
takes several decades before the effect is noticeable.
It would be impracticable to stress-relieve musical instruments because the
temperature involved would damage non-metallic parts including the lacquer.

Cheers

Bob Smith
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