Klarinet Archive - Posting 000374.txt from 2003/12

From: mginesi@-----.net
Subj: RE: [kl] Hard Rubber Mpc. Deterioration
Date: Wed, 17 Dec 2003 23:55:11 -0500

as to the damage that might occur to our hard rubber mouthpieces, Kasper and
other tradenames...

what follows is to be helpful in understanding the process of natural decay
that takes place with all hard rubber items....mouthpieces included. i'll
start by saying that when you look at your mouthpiece and see a brownish,
yellowish , greenish oxidation upon it...best it be left alone. do not buff
it out...do not sand it out... do not remove it!..
you can rub it gently with a soft cloth to reduce the visibilty of it [for
those to whom only a shiny black mouthpiece is the penultimate] it is your
best protection against the forces of nature awork upon your mouthpiece.

in the matter of explaination....

We can thanks Mr. Goodyear for the fortunate accident in 1839 that produced
the end result of ‘vulcanization’ of rubber [the term proposed by Mr
Brockedon to Thomas Hancock who took out the first patent for the process in
1843]

the vulcanization of rubber is the process of reacting rubber with sulfur or
other suitable agent so as to change its physical properties in the direction
of decreased plastic flow, diminished surface tackiness, and increased
tensile strength. When we add an amount of sulfur that equals 25% of the
compound we will obtain EBONITE or HARD RUBBER.

The basic ingredients of a vulcanizing system were sulphur, a base oxide such
as lead oxide or zinc oxide and heat. Other chemicals (‘accelerators’) could
be added to the mix to speed up the process at any given temperature. over
time antioxidants and antiozonants were added to the compound as well.

The chemical structure of the natural rubber vulcanizate is such that the
polymer chains of an unvulcanized rubber were joined together (crosslinked)
by sulphur bridges to give a three dimensional network and it was this which
provided the increased elasticity of the vulcanized product.

The details can be extremely complex. Sulphur could initially attach itself
to one of several carbons within the monomer unit and could then either
remain there or undergo a chemical shift to another carbon atom. The length
of the sulphur bridge was also variable, being 1, 2, 3 or even more sulphur
atoms while the final complication was that the sulphur bridge might not have
been formed between two adjacent polymer molecules but it could have looped
back to the same polymer chain from where it started.

Once the product exists, the potential for damage falls into several groups.

Abrasion and external chemical attack may be unavoidable.

Temperature, sunlight and stresses can all accelerate or initiate the
chemical changes.
These changes, known as ‘ageing’ involve three distinct pathways for most
(sulphur) vulcanizates. These can be identified as:

continuing sulphur chemistry
shelf ageing
atmospheric ageing

Sulphur chemistry is particularly important in vulcanized products which are
resisting a distorting force and that will include anything from a stretched
rubber band to a flat tire. This chemistry does not stop when the vulcanizing
temperature is reduced from some 150oC to ambient - it just proceeds more
slowly. One of the features of vulcanizate ageing is ‘set’ and this is caused
by the polysulphidic bonds which form the chemical crosslinks between polymer
chains breaking and the loose ends re-attaching to either their original
partner or another loose end (crosslink reversion). If the vulcanizate is
under a distorting force, then, as the bond breaks, the elasticity of the
polymer chain causes it to relax against the force so that the bond will
reform further down the chain. The result is a slow "slippage" of the
vulcanizate which cannot be reversed although it can be minimized by the
appropriate choice of crosslinking agents, an option not available to the
conservator. None of this will stop the 'sulphur chemistry' continuing but
this will not, by itself, harm the 'item' for several centuries.

Shelf ageing is basically oxidative degradation and, apart from the obvious
influence of oxygen, one must consider the catalytic effects of heat, light,
internal and external stresses or strains and pro-oxidant metals. The
chemistry of oxidative degradation of a sulphur vulcanized polyolefin such as
natural rubber proceeds through at least one chain reaction sequence which
introduces C-C and C-O-O-C crosslinks between polymer chains as well as C-O-O-
C rings within the same polymer chain, and another set of chain reactions
between oxygen and the sulphur atoms of the crosslinks or pendent groups.
These two sequences of chain reactions can result in both chain scission and
the formation of additional crosslinks. The reactions between sulphur and
oxygen can also, eventually, lead to sulphuric acid formation, a particular
problem with ebonites.

As oxidation continues the chain breakdown may become more significant and
the hard surface then softens and turns sticky. To complicate matters
further, under certain conditions this order can be reversed and an initially
sticky degraded surface can harden with further oxidation.

Light-catalysed oxidation can result in an inelastic skin which, as it
thickens, cracks in random directions and produces a pattern known
as "crazing". Because of the light absorbing properties of black-filled
materials, this effect is not normally seen in them. In many real life
vulcanizates of reasonable bulk under ambient conditions, it seems that the
ingress of oxygen is limited and, apart from the surface few millimetres or
so, the bulk rubber remains in excellent condition.

Atmospheric ageing differs from shelf ageing in that it is characterized by
the attack of ozone on the rubber. It is essential to be aware that this is
not just another form of oxygen-induced degradation as the mechanism is quite
different, with simple bimolecular ozonolysis of the rubber olefinic double
bond being followed by immediate cleavage to give two carbonyl end groups. If
the rubber is under any sort of stress this will result in 'atmospheric
cracking' in which the cracks are perpendicular to the direction of
elongation. As early as 1931 it was shown that 'ozone cracking' was different
from 'light ageing' and took place more readily in the night than during the
day.

It should also be realised that for modern black vulcanizates of reasonable
bulk which are being stored or displayed or utilized under ambient
conditions, the ingress of oxygen is limited and, apart from the surface few
millimetres or so, the bulk rubber will remain in excellent condition for
display purposes almost indefinitely.

The ultimate barrier layer must be an enclosed container which can be filled
with an inert gas.

the choice of the material from which to construct the container is not
always obvious as many plastics themselves decompose all too rapidly. Simple
plastic bags are readily permeable to air but there are impermeable multi-
laminate ones which, unfortunately, are not suitable for playing the clarinet
[although they could be used for long-term storage.]

Perhaps glass is the best material for both storage and display - and we
could place ourselves within a glass box [inert gas and all] within the
orchestra...would have to mic the section, however...

unfortunately, nothing will reverse degradation which has already occurred.

michael ginesi

> Don -
> I have a circa 1940 Goldbeck which was not used for about 40 years. I
> discovered that I still had it in 1998 and have used it exclusively since
> then. For me, it is a perfect mouthpiece. My teacher and I can tell little
> difference between it and his Kaspar. Measured roughly, my Goldbeck has a
> 1.02 mm tip opening.
> My question concerns deterioration of hard rubber. Educate me, please.
> This is of interest to me because recently I noticed an almost microscopic
> "slit" on the facing side of the tip (which is quite thin). It looks like a
> very tiny "de-lamination" as it follows the curve of the tip, although I
> doubt that the hard rubber is laminated. As an old mouthpiece, it is made
> of pre-EPA (ugh) hard rubber.
> Maybe this is the deterioration of which you speak. Of course, the tip,
> which is very thin, takes a lot of "punishment" from the vibration of the
> reed and from tonguing. I have not noticed any change in the mouthpiece's
> characteristics so far. But that may happen.

> Do you have a price on your Goldbeck? I might be interested if the tip
> opening is comparable to mine.
> I don't know if the above makes sense, but if you or any of the mouthpiece
> experts can enlighten me concerning what may be happening to my Goldbeck, I
> will appreciate it.
> Regard,
> Gene Nibbelin
>
> -----Original Message-----
> From: Don Hatfield [mailto:dhatfield@-----.org]
> Sent: Friday, December 12, 2003 9:11 AM
> To: klarinet@-----.org
> Subject: Re: [kl] Copying Kaspar
>
> Just to add two cents-worth of opinion after reading these recent posts -
> I am fortunate to have three Ann Arbor Kaspars and a Cicero Kaspar that I
> can attest to as "original", as they came directly from Ann Arbor when I was
> a junior high schooler, through my private instructor who had been a student
> at UM in the late fifties/early sixties, and had remained close to Mr.
> Kaspar. The only adjustment to any of them was by Kaspar himself when we
> sent a couple back for 'tweaking'.

> My view - I love the mouthpieces, and have used them sparingly over the
> years except for the Cicero, which was my staple until I quit playing
> regularly about eight years ago. I have started the search for replacements
> this year as I am returning to playing and teaching again, and because I
> know the Cicero will eventually give up the ghost (and likely is as I write,
> considering the stability of the hard rubber after all these years) and
> after dusting off the Kaspars it is clear they need some refacing and
> adjusting, which I can't see doing to a mouthpiece that old now, I'd rather
> put the money in new mouthpieces.
> Also, as mentioned here, things are continually changing - instruments,
> halls, reeds, etc. So I am planning to search until I find what I need and
> am happy with, knowing that the search may take some time. It's funny (to me
> at least) that the two mouthpieces so far that I've found in my collection
> that come close to the Cicero are an old Brilhart hard rubber #3...it's

> actually an awesome mouthpiece in its own right...and an ooooold -
> surprise - Goldbeck that I have also kept squirreled away for thirty years.
> Neither is just like it (the Goldbeck IS very close, for obvious reasons),
> but I don't expect to find that ideal in whatever I settle on anyway, I may
> end up with a different sort of setup than I would have considered when I
> first started this search. I will have to keep a journal of my findings and
> progress, because I have never played a Fobes, a Pyne, a Smith, a Grabner,
> and a couple others on my prospect list. It means shelling out some bucks,
> but it's worth it to me in the long run to put the pressure on my budget.
>
> Don
>
>
>
> > Greg makes an important point here. It is rare now to find Kaspars that
> have
> > not been adjusted (or ruined) by other makers.
> > I believe the prevalence of refaced Kaspars is a further indication that
> > needs in mouthpieces are changing from what the players used during the

> long period of production by the Kaspars (about 1920 - 1975).
>
>
>
> ---------------------------------------------------------------------
> Klarinet is a service of Woodwind.Org, Inc. http://www.woodwind.org
>
>
> ---------------------------------------------------------------------
> Klarinet is a service of Woodwind.Org, Inc. http://www.woodwind.org
>

---------------------------------------------------------------------
Klarinet is a service of Woodwind.Org, Inc. http://www.woodwind.org