 The Clarinet BBoard
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Author: Molloy
Date: 2007-05-01 13:05
What's the lifespan of hard rubber?
Wood will decay completely in a few years in some conditions and last millennia in others. Is the story similar for rubber? Is it too soon in its history to know?
I would guess that a major differnce between wood decay and rubber decay is that the one is primarily biological (driven by bacteria, fungi and insects) while the other is primarily chemical. But maybe I'm wrong about that...
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Author: David Spiegelthal ★2017
Date: 2007-05-01 13:20
Don't worry about it -- your hard rubber mouthpiece will outlive you, your children, and your grandchildren.
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Author: bandman
Date: 2007-05-01 13:32
I would not worry about the wood used in clarinets either. I have seen clarinets that were 100 years old and still in good shape.
Retired Repairman
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Author: L. Omar Henderson
Date: 2007-05-01 13:47
Hard rubber goes through a process of vulcanization where a catalyst and heat cause the monomer chains to polymerize and form cross links between polymer chains. Hard rubbers begin to "decay" immediately after the vulcanization process. The time course depends on a lot of factors including exposure to ultra-violet light radiation, heat, and oxidizing agents in the air. The degree and ultimate structure of the polymerization reaction forming the hard rubber and subsequent tempering steps determine the final structure and its susceptibility to breaking of the cross links holding the rubber together. Modern rubber technology has improved the rate of "decay" of the polymerized chains - breaking of crosslinks and unravel ling polymerized chains, modern catalysts improve polymerization efficiency and complexity, UV inhibitor additatives have been included in rubber formulations, and now quality control steps analyze the structure of the rubber to form a blueprint characteristic of various batches of rubber which can help predict the longevity of the formulation.
Older catalysts like sulphur were adequate but relatively poor catalysts compared to modern exotic metal catalysts used to manufacture hard rubber. The purity of the starting material latex has also improved and changed over the history of rubber manufacture and a lot of the contaminants such as plant proteins found in older raw latex stock have been removed and the starting material further refined. The rubber trees themselves have been hybridized and the shift to different growing areas around the world has changed the quantitative makeup of latex stocks available today to make hard rubber. The type of catalyst used and the number and types of impurities in the starting latex stock determine the nodes of polymerization and therefore the resulting lattice structure of the final product. The lattice structure and blueprint signatures of antique hard rubbers is different than the lattice structures formed in todays hard rubber because of the impurities of starting materials used, catalysts, and type of vulcanization machinery available at the time. Whether the current "snapshot" of the "decayed" antique hard rubber is indicative of the beginning lattice and polymerization structure is a point of scientific conjecture.
Older hard rubber objects will "decay" faster than newer formulations because of the structure of the polymer formed using an excess of sulphur as a catalyst. We still have hard rubber mouthpieces in pretty good condition that were made 50-80 years ago so the lifetime of even these antique objects in long lived. There were probably more bad batches of rubber produced in earlier times and they may show more "decay" than similar batches made at the same time. Exposure of these items to heat, UV radiation, and oxidation elements probably causes a spectrum of "decay" characteristics even within a same batch of antique hard rubber examined today.
The bottom line answer - decay will and does happen but at a variable rate. Decay to fracture failure may take 25-100 years (or more) depending on the batch characteristics, formulation, and exposure to decay producing elements.
L. Omar Henderson
www.doctorsprod.com
Post Edited (2007-05-01 14:30)
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Author: Terry Stibal
Date: 2007-05-01 14:39
Other than noting (with considerable pleasure, I might add) the use of the proper spelling for the element "sulphur" by Omar above, and that the mixing process for rubber in the past was more of a cooking procedure rather than a precision chemical process, I will only add that the "production" of rubber (particularly prior to World War II) was a very time consuming and manual process.
In order to get the natural, plant-derived latex into what we consider to be "rubber" form, the various additives (primarily including carbon black for the color and sulphur for the cross linking need to be kneaded (as in cooking kneaded) into the resilient mass of the raw stuff. This is the basis of the Goodyear process,
("Synthetic rubber" was only really produced from about 1938 forward, so anything in the musical instrument line prior to that date (and most of it afterwards up to about 1950 or so) was the natural item. And, even today most rubber products contain a significant fraction of natural latex to obtain several desired finished product qualities.)
Rubber is not "mixed" in the same sense as is something like paint pigment; i.e., there is no "uniform" distribution of the components obtained by stirring. Instead, rubber is "milled" in a device called (oddly enough) a "mill", consisting of a large pair of inward rotating roller over a catch pan.
The mill operator takes the raw rubber mass, drops it on top of the mill rollers, and take the resultant "milled" product out of the bottom, As the milling procedure continues, the various additives are worked into the mix, and what was once a sticky, waxy translucent brown mass gradually turns into to the finished appearance.
(Hopefully during this process, he does not get an arm caught in the mill and worked into the mix. Some of the more gruesome fatalities that I have investigated over the years have involved rubber mills.)
Cut through and examined under a scope, you can actually see the layers formed as the material is worked through the mill. It resembles a cross section of a Damascus steel sword blade, with dozens of microscopic layers formed as the material is kneaded back onto itself by the multiple passes through the mill.
Once the "dough" is thoroughly mixed, the mass is then forced into molds and cured there by the application of steam-supplied heat. Whether in the form of a tire (itself "built up" out of multiple layers of rubber and other substances) or a hard rubber rod, the resulting cured item has taken the final form that it can be moved to take. (Mouthpieces and instruments are then created by machining the cured material with machine tools, similar to those used with metal.)
As older rubber "mixtures" age, the various agents outlined in Omar's posting can have an effect on the material. We in the music business have grown accustomed to old mouthpieces and instruments that have gone "green"; this is the result of the sulphur in the mix migrating from the finished product. You may know of someone who covers up the wheels on an infrequently used travel trailer - what that person is doing is cutting down the ultraviolet light exposure that causes the same sort of thing from happening with tires.
(Incidentally, the good folks at Consumer Reports have advised us to always purchase the newest tires available (this by the manufacture date, which can be figured out from coding on the tires), the better to avoid devulcanization problems experienced with older tires.)
(I once bought a house that had, among other charming features, a pile of tires in the crawl space below the building. These dated from the 1930's or so, and they crumbled when we tried to lift them out to clean the place up.)
(The reason that they had probably been dumped under the house in the first place is because you cannot bury a tire with any expectation of it remaining buried. The expansion and contraction of the material with normal temperature changes tends to have them rise to the surface, hence the huge piles of tire dumping sites. I have always wanted to bury an old rubber mouthpiece and see if it too shares this characteristic.)
The rubber milling process works the other way as well. Among the other interesting industrial facilities located in the East Saint Louis IL area, there is a plant (Midwest Rubber Reclaiming) that specializes in recovering the rubber from old tires.
They do this by heating them up (with steam heat again) in large autoclaves, then leaching the sulphur from the rubber mixture with a solvent (carbon disulphide, I think - nasty, wrath of God stuff, but it does the job). Once this is done, they macerate ("chew") the resultant gummy mass up, separate the steel belting and synthetic fibers through a variety of processes, and then end up with an inferior grade of raw rubber (synthetic and natural) stock.
I have one mouthpiece from the 1930's or so that I still use, even though it has turned a yellow green color over the years. Despite this change, I don't notice any difference between it and a copy that I had made in the 1980's to match. So, I'd not worry too much about stuff from the 1900's, at least not that stuff that is likely to still be in use.
leader of Houston's Sounds Of The South Dance Orchestra
info@sotsdo.com
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Author: tictactux ★2017
Date: 2007-05-01 15:25
> Hopefully during this process, he does not get an arm caught in the mill and
> worked into the mix.
Now I see those Vandoren "swirly" two-tone mouthpieces in quite a different light...
--
Ben
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Author: Chris P
Date: 2007-05-01 15:51
What about the lead content in ebonite?
When did the regulations come in to ban the use of lead?
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: Alseg
Date: 2007-05-01 16:21
For the purposes of playing clarinet, the rubber is fairly stable, BUT....and this is important, IT CAN WARP WITH MODEST HEAT.
I milled barrels from a billet of cured hard rubber.....any heat generated by the process caused distortion where the mandrel held the socket ends.
It requires patience.
Bottom line....do NOT leave quality hard rubber products in a location (car trunk, near a furnace, etc) where they can absorb heat.
This is one reason why older mouthpieces need reworking from time to time.
Former creator of CUSTOM CLARINET TUNING BARRELS by DR. ALLAN SEGAL
-Where the Sound Matters Most(tm)-
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Author: L. Omar Henderson
Date: 2007-05-01 16:35
Hard rubber, even glass for that matter is an amorphous liquid whose movement has been slowed down by a structure imposed by crosslinking or crystal formation. Old glass windows will be thicker at the bottom because of the flow of the liquid. Heat, as noted by Allan will speed up the process and lead to distortion of the cast or milled original form. Granted the distortion under usual environmental conditions is long term (many years) but it is reasonable to understand the basic properties of the materials involved and take precautions not to speed up the process or encourage "decay" in hard rubber with heat, UV exposure, or environment pollutants like ozone. I do not think that the FDA or EPA have been called in to look at potential leeching of lead from old mouthpieces with mouth contact but if you are worried about your old Chedville Steel Ebonite mouthpiece being a potential health hazard for you - please send it to me for proper hazardous waste disposal (after I try it out of course !!!).
L. Omar Henderson
www.doctorsprod.com
Post Edited (2007-05-01 16:53)
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Author: L. Omar Henderson
Date: 2007-05-01 17:25
Ben, perhaps I am the victim of this urban legend but perhaps not - http://math.ucr.edu/home/baez/physics/General/Glass/glass.html In any event I am thrilled at the challenge to learn more and investigate the literature. Anyway, it is evident that heat will cause hard rubber to distort and "decay" the crosslinking holding the amorphous liquid or solid in rigid form and is accelerated by heat, UV, and oxidizers.
L. Omar Henderson
www.doctorsprod.com
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Author: Clarence
Date: 2007-05-01 17:30
I have a Conn Eb clarinet (approx date 1929) that is hard rubber.
The rubber looks as good as new.
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Author: Alseg
Date: 2007-05-01 17:36
WMS (Waste Management Systems, Inc) has designated my workshop to provide a careful Melamine assay. This stuff (originally in syrup form) is responsible (allegedly) for pet deaths.
Before sending your vintage Ched, Lel, or Kaspar to Omar, forward them to me for this vital analysis. We would not want to leech chemicals into your home...or into you.
I will provide this service free of charge.
Disclaimer. I am not an employee of WMS. Melamine assay is conducted using the Skrtch.N.Sniph technique, yielding 99.998% false positives.
Former creator of CUSTOM CLARINET TUNING BARRELS by DR. ALLAN SEGAL
-Where the Sound Matters Most(tm)-
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Author: L. Omar Henderson
Date: 2007-05-01 17:55
Clarence - I have a dull finish, olive green and yellow hard rubber "A" clarinet about 50 years your Eb's senior that was rescued from "lampville" by David Spiegelthal that I actually paid good money for and it plays beautifully.
Note that WMS has failed their last three proficiency testing challenges by the EPA and their hazardous waste desposal certificate has been suspended so you really should send the mouthpieces to me. My laboratory has been recently certified by the NLREAM (National Lead Remediation, Evaluation, and Mediation) network to analyze and dispose of suspected environmental lead contaminated objects. Melamine will make you sick but lead will make you crazy, dumb and kill you too. So if you are already crazy and dumb send me the mouthpieces - before they kill you.
Actually I did some consulting work for a "name" company before they introduced a new MP to test for potential chemicals leeching from the MP in case FDA or EPA decided to declare MPs a medical "device" which has skin contact.
L. Omar Henderson
www.doctorsprod.com
Post Edited (2007-05-01 18:56)
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Author: tictactux ★2017
Date: 2007-05-01 18:39
Does anyone in here know a confectioner who does Chocolate Chedevilles?
I want one with >70% cocoa for a dark tone.
--
Ben
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Author: BobD
Date: 2007-05-01 21:55
Perhaps we should differentiate between melamine and melamine resin. The latter has been used for some mouthpieces and various other products commonly made from phenolic resins (Bakelite types). Probably its primary advantage is the availability of more colors than just black and brown. "Melmac" dinnerware was popular in the '50s.
Bob Draznik
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Author: CPW
Date: 2007-05-01 23:32
Hey, didn't ALF come from the planet Melmac?
Tacky Tacky
Against the windmills of my mind
The jousting pole splinters
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Author: Arnoldstang
Date: 2007-05-02 03:43
Omar, Your response reminds of years back when David Straubinger was working on cane for oboe reeds. He was doing something like bifunctional cross linking of fibres in the cane to add stability...ie make it play better. He gave that up and went on to make Straubinger pads and Straubinger flutes. There is a lot of music in science!
Freelance woodwind performer
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Author: Bassie
Date: 2007-05-02 09:39
Recently I got a new Selmer C85 115 to try. It played harder than my C85 120, which seemed wrong. So I put the 120 on a measurement table... lo and behold, it's a different shape from the spec (noticeably more closed).
The mouthpiece has clearly changed over the ten years I've had it. There appears to be some wear (looks polished) near where the reed leaves the table. I don't know about warpage. Personally I think the Selmer compound is slightly softer than some others... has a different look to it too (slightly matt, granular almost). I'm gonna reface it (well, it's no good to me as it is).
The other thing old mouthpieces do is collect a wonderful sulphurous smell and a crusty brown patina. That's the thing with organic compounds: leave 'em anywhere for ten years and they'll 'do chemistry'.
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Author: Don Berger
Date: 2007-05-02 14:30
Is a Dangerous Thing, {attributed to "good ole" B Franklin, now where did I put my Bartlett's?} . I've been following this thread's "development" for some time, perhaps perversely [sp?] to see how many "U L's" could be repeated/generated, trying hard to NOT enter the "fray". Now that we have that FINE tech. "paper" included and ref'd here [Many TKS, Ben TTT], I'll throw in a few semi-scientific thots. H[ardened] R is no longer rubber, its a highly crosslinked ThermoSet "resin", a solid, [not a "glass"], which when heated [or otherwise chemically decomposed] does NOT become a liquid, but becomes ashes and gas. It has similar physical properties to ThermoPlastic resins, [with which we are more familar]. It is quite "long lasting" in our moderate use, and does NOT leAch out lead or other "heavy" metals [used in the "vulcanizing" mix] to a dangerous extent. Yes, older formulations do color [brown, green , yellow?] on oxidative exposure [sunlight and air, etc]. In my experience, the patina seems to be "protective" and diminishable, and may release some sulfur compounds [oxides?]. Gosh, "nuff?, [too much ?] for now. Don
Thanx, Mark, Don
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Author: Terry Stibal
Date: 2007-05-03 16:16
While not a industrial chemist, I have to play well with their sort all of the time, and it is amazing how little the general public knows about plastics and other "resins", of which rubber was the first practical one.
One book that I've found useful when dealing with lay folks who are not up on their "plastics" knowledge is called Plastic - The Making of A Synthetic Century, by Stephen Fenichelli.
Written by a business writer rather than by a chemist, he does an excellent chronological job of laying out the history of the substances, along with the historical context of each. (Example include the tie ins with early plastic development to sea turtle and elephant die off, and that modern rubber is based completely upon synthetic rubber developed by we Germans as a result of being cut off from most natural supplies during World War I).
An excellent book, and quite reasonable on Amazon.com, the last time that I checked.
leader of Houston's Sounds Of The South Dance Orchestra
info@sotsdo.com
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Author: Don Berger
Date: 2007-05-03 18:33
TKS, Terry, I plan to get a copy, can always learn more ! Don
Thanx, Mark, Don
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Author: Terry Stibal
Date: 2007-05-03 19:19
The book is full of obscure facts and figures, most of which checked out when I looked into them. It's not written in a scholarly fashion, but the information is dead on accurate for a lay person.
Fun fact from the book: George Eastman, the "inventor" of the modern camera with roll feed film and remote processing, shot himself in the head or heart with a Luger pistol. He left a note that said (in effect) "Why wait?"
(There are some that maintain that he was anticipating the advent of digital, film-less cameras...)
Others included are the true origins of Velcro and Teflon (neither of which had the slightest thing to do with NASA and astronauts), why Goodyear died a pauper, and the aforementioned elephant and turtle allusions.
leader of Houston's Sounds Of The South Dance Orchestra
info@sotsdo.com
Post Edited (2007-05-03 19:22)
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Author: BobD
Date: 2007-05-03 20:30
A look at "resin" jewelry on the auction website is interesting. Such jewelry was popular during the Depression years and now commands very high prices.
My old ACE hard rubber comb still works.
Bob Draznik
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