Klarinet Archive - Posting 000346.txt from 2010/09

From: Jennifer Jones <helen.jennifer@-----.com>
Subj: [kl] Vinegar turns mpc green
Date: Sun, 12 Sep 2010 01:13:08 -0400

For the record:

A ~1 hour soak in a 5% solution of room temperature (~78F) distilled
white vinegar did not remove the white/tan deposits and turned my
Selmer C85 mouthpiece green. In addition to turning the region below
the liquid green, fumes also turned the portion above the liquid line
green. The portion of the submerged facing also became paler. My
mouthpiece now has a vinegar induced "suntan". The cork was not
submerged.

The region traditionally under the ligature did not turn colors nearly
as much as the rest (incl. the portion above the liquid line). This
and the fact that this mp has not been out in the sun much argues
against a purely sun-induced color change of mouthpieces. The storage
of the mouthpiece with the ligature in place probably restricts oxygen
exposure of the mouthpiece, such that the region under the ligature
does not receive as much exposure to oxygen and hence does not rot and
turn green to the extent that the exposed portions do. Vinegar must
either accelerate rotting of the deteriorated portion, leech materials
out or otherwise change its color.

The mouthpiece was purchased in late 1998 or early 1999. It now
smells like vinegar and my old greened vulcanized rubber mouthpiece
that it replaced. There was no residual vinegar taste, but there was
a mild smell. I also washed the mp with soap and water after using
vinegar.

Given that lime-away and CLR are stronger mixtures of acids, it does
not make sense to try them on the mouthpiece, as it will probably turn
greener.

-Jennifer

On hard rubber degradation:
incl. continuing sulfur chemistry, oxidative degradation, as well as
catalytic effects of internal and external stresses, heat and light
http://test.woodwind.org/Databases/Klarinet/2003/12/000374.txt

Post by Lelia Loban on a hard rubber clarinet that has relatively
untarnished silver keys:
http://test.woodwind.org/Databases/Klarinet/1998/11/000487.txt
It is generally understood that the sulfur in vulcanized rubber
tarnishes silver. Lelia questions the chemical differences between
hard and soft rubber. She has found that soft rubber cause a lot of
tarnish whereas hard rubber causes little or none, based upon silver
trimming on hard rubber pens and hard rubber sax and clarinet
mouthpieces with silver ligatures that do not have tarnish that
appears to be caused by the rubber. I think it may be a matter of the
extent of cross-linking.

This post indicates that acids reverse the color change:
http://test.woodwind.org/Databases/Klarinet/2004/05/000519.txt
I argue that this is wrong, because my mouthpiece turned green when I
put it in acid. There is further argument that the reaction causing
the color change can be reversed. I argue that the reactions in
rotting rubber cannot be completely reversed because of oxygen induced
breakage of the carbon chains of the rubber molecules.

The searches conducted:
hard rubber sulfur mouthpiece

My post on mouthpiece cleaning with ingredients of lime away and CLR:
http://test.woodwind.org/Databases/Klarinet/2010/09/000221.txt

My post on vulcanized rubber deterioration with jumbled thoughts about
the mechanism:
http://test.woodwind.org/Databases/Klarinet/2010/09/000114.txt
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