[Harp-L] Vibratory Stress Relief (VSR) for reeds

[Rick Epping <rickepping@xxxxxxxxx>]

Hi folks,

This message is about one possible benefit of using an ultrasonic cleaner
on newly replaced reeds.

The work that reeds are subjected to through such procedures
as profiling, riveting, centering, chamfering, curvature adjustment and
gapping, adds stress to the reeds.  As the tuning of a reed can be affected
as a reed de-stresses, the Hohner factory gives newly assembled reedplates
a rest period to de-stress before tuning.  Alternatively, Asian harmonica
factories heat treat reedplates to de-stress them.

In my experience, new replacement reeds that I have riveted onto a
reedplate tend to go up in pitch over the course of a week or so, and
require an additional tuning once they become stable.  Lately, however,
I've been using an ultrasonic cleaner in an attempt to VSR treat plates
with newly replaced reeds, and find that after using the cleaner's maximum
time setting of 8 minutes, new reeds increase in pitch by as much as 8 or 9
cents.

I've only been paying attention to this effect for the last half dozen or
so reeds I've replaced and have not as yet experimented with employing
longer periods of VSR, but it looks like it might be a useful treatment for
quickly stabilizing a reed's tuning, if not also for delaying the onset of
reed failure by elimination of residual stress before a new reed is
subjected to playing.

More on the subject of VSR here:
http://en.wikipedia.org/wiki/Vibratory_stress_relief

Best regards,
Rick