Re: [Harp-L] cryogenic brass reeds

[Joel Fritz <williemctell@xxxxxxxxx>]

I don't know about cryo treatment of copper alloys.  It's used with high 
alloy content steel that transforms sluggishly on hardening.  Many shops 
use liquid nitrogen for this purpose.  The makes a normal person's eyes 
roll back in their head explanation is the transformation of retained 
austenite.  It's commonly used on some tool steels as well as the high 
carbon stainless generally used for expensive knives and dental 
instruments.

I did a brief web search on cryogenic treatment of copper alloys.   I 
found only one metallurgical journal article on the subject and it dealt 
specifically with beryllium copper although it mentioned copper alloys 
in general in the introductory section.  Apparently cryo treatment does 
result in stress relief.  I'm not sure that stress relief is worth the 
trouble for harmonica reeds although I could be wrong.  It might 
increase the life but it would also remove some of the work hardening 
resulting from forming.  It seems to me that a harder, i. e. stronger, 
reed is a good thing.  It does appear that liquid nitrogen would be 
adequate for the job although you couldn't do the gradual temperature 
reduction with a bucket of liquid N2.








On 5/30/2012 7:11 PM, Robert Hale wrote:
> I have become curious about claims for freezing my reeds to double the
> life. Anyone with personal experience?
>
> Cryogenic Process:
> CRR, or cryogenic resonance restoration, is the gradual lowering (1 degree
> per minute to -325 degrees)and raising of the temperature of the
> instrument. Theoretically, it relieves stress and tension in the metal and
> improves the instrument's response and resonance. (Claims to reduce stress
> fractures, the main reason for reed breakage.)
>
> "This is a controversial method and the jury is still out as to whether it
> actually makes a difference. It has yet to be proven in blind listening
> tests." http://www.musicservices.co.nz/brass_temper
>
> Robert Hale
>
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