Subject: Re: what is the effect of cooling brass to -300C

From: [email-masked] (Joel Bristor)
Date: Sun, 26 Feb 95 17:22:33 EST

I am a brass instrument repairer with over 20 yrs experience doing work
for a wide range of folks, including some pretty fine professionals.
Sometimes my role is a little like that of a barber or bartender - people
ask a lot of advice about the latest trends and fads in brass instruments.
 
As you can well imagine, many people have asked my opinion of the "horn
freezing" treatment.  I know little compared to some of the metalurgists
participating in this thread.  Respecting the right of a person to offer
a service, effective or not, I always invite customers to spend their
money as they see fit.  I know well the uses of annealing brass to certain
carefully controlled temperatures.  I am sceptacle regarding the effects of
this "freezing" treatment.  As this treatment is billed to relieve stresses,
I have carried one concern.  Most brass instruments (trumpets, trombones,
french horns, etc.) are made of brass (70/30 or 85/15), nickel, and a fair
amount of soft (50/50, 60/40, 70/30) and silver solder.  Where nickel tubes
encase and are soft soldered to brass tubes, I wonder if the slightly
different expansion coefficients might damage the integrity of the solder
joints.  I know that freezing (in a household unit) is a great way to
break the bond between a badly corroded pair of these telescoping tubes.  If
the tubes move apart enough to break that bond, would they not move enough
to break or damage solder joints?
 
Thanks in advance for any bonifide scientific information.
 
Joel Bristor