 The Clarinet BBoard
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Author: Hank Lehrer
Date: 2003-06-13 23:36
Hi,
I was in the process of re-corking a couple of mouthpieces recently when the sheet cork I was using kept breaking. This happened as I began to apply the cut strip to the mouthpiece after the contact cement had dried and was ready.
Not able to wait for an order from Ferrees, I went to the local hardware store and got some synthetic sheet cork at a very reasonable price and used it. I suspect this type cork is made of cork particles from some type of manufacturing process with a binder of some sort.
However, what I am wondering is:
1. are any of the techs on this BB using synthetic cork on MPs rather than natural product.
2. Is there any way to "moisturize" the old sheet cork that I have in an atempt to make is more flexible.
Thanks.
HRL
Post Edited (2003-06-14 23:00)
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Author: jbutler ★2017
Date: 2003-06-13 23:46
Hank,
1. There are different types of synthetic cork(Tech-Cork, Gummi-Cork, Sorbothane, etc) being used on instruments these days. Being more a "traditionalist" I always use natural cork products.
2. Natural cork can be "steamed" to hydrate it. Five minutes should be enough. It becomes more flexible.
jbutler
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Author: Gordon (NZ)
Date: 2003-06-14 00:04
1. Some manufacturers are using synthetic or composite corks. I so far find them to be vastly inferior to the natural product. I don't think many reputable technicians would be using other than natural cork, except in special situations, such as when the cork groove is too deep. The composite corks have too much friction on the surface, cork grease is not well retained, and too much pressure is needed on the surface (from the tenon socket) to utilise any resilience that it has. It is effectively a far harder material than natural cork.
2. Some technicians advocate steaming or boiling. This did not work for a very old, brittle sheet that I was given. Some advocate squeezing it in a vice, or rolling it prior to use. It is said that cork sheets should be stored in a fairly humid environment, say 50 to 60%.
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Author: Hank Lehrer
Date: 2003-06-14 02:40
Jbutler and Gordon. I'm going to try to hydrate the cork with some steam.
One person gave me a tip, off-line, which was to put tape over the outside of the cork while installing and that might provide enough strength to be able to make contact with the glue before the cork breaks.
Thanks everyone.
HRL
Post Edited (2003-06-14 02:45)
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Author: ron b
Date: 2003-06-14 04:39
Just curious, Hank -
When you cut your cork strip, did you cut with the grain or across the grain?
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Author: Hank Lehrer
Date: 2003-06-14 12:42
Hi ron b,
I did not know there was a grain to the cork but I just went and cut two pieces, one with and one across the sheet, and both broke the same way. So....
HRL
Post Edited (2003-06-14 12:43)
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Author: Gordon (NZ)
Date: 2003-06-14 12:43
Perhaps that question should be rephrased: does the sheet have the ('grain') holes perpendicular or along the (large) surface.
The latter would be disastrous for a tenon cork. Almost all cork sheets on the market are the former. The latter are intended for use as pads or key corks.
If the holes in the sheet ARE perpendicular to the surface, then in theory cork does not have a grain that makes cutting the strip in one direction preferable to cutting it in a direction at right angles.
However there is the odd sheet that has holes that are severely oval, in which case these ovals should be aligned with their long axes parallel to the long side of the strip.
Regarding the tape idea. Normally, when wrapping the cork around the tenon, the outside of the cork would be put under tension, increasing the likelihood of cracking. Use of tape would prevent the outside of the cork from being put under tension. Instead, the underside of the cork would be put under compression, which does not encourage cracking at all. Hence I consider the tape idea to be a viable solution, worth trying.
Post Edited (2003-06-15 00:34)
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Author: BobD
Date: 2003-06-14 13:01
Those who repair instruments for a living have to make a profit so they do what they know works best for themselves and their customers. As an amateur I do a number of things for experimental purposes for my own use. If I discovered a way to make gasket cork from Ace Hardware "work ok" maybe I wouldn't tell the world. If you're using it for a customer you have to stand behind your work. I do use a circular knife to cut cork which seems to help and I adhere it to the tenon very slowly with a "rolling" finger motion. I let it sit overnight which usually obviates the need for tape or string pressure. If you've done corks routinely then I suspect you cut it across the grain or you just got a bad batch or you were rushed.
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Author: Hank Lehrer
Date: 2003-06-14 17:15
Hi Everyone,
Actually, with Gordon's definition, I easily found that the cork was originally cut in the correct manner. I do now believe that my primary problem is that the cork is many, many years old (try 25) and has become very dry.
As far as technique, as a long time band director, I have changed many a tenon, sax neck, and mouthpiece cork over the years. Although not as fast as someone doing this everyday, I can adequately accomplish the task. However, as a point of reference, the primary reason that I tackled these type repairs was that I was usually many hours from a repair shop (we did not have "techs" in those days).
Thanks for all the insight into grains, technique, etc. I just got done soakinga small sheet of cork to see what happens. Also while wet, I rolled it and put a rubber band on to keep the sheet in that postion. This should relieve some of the tension in the cork.
HRL
Post Edited (2003-06-14 19:07)
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Author: Ray
Date: 2003-06-14 20:01
Hank,
I am pretty new the the business of repairing clarinets, but I have had good instruction and my work has been successful so far.
Around these here parts (north Texas) word has it that a product called Gasket Seal that is available at an auto parts store called Auto Zone works well for tenon corks.
This stuff is tiny bits of cork in a binder of black rubber of some sort - I kind of hope its Neoprene, because that has a nice ring to it. It is far cheaper than good cork. (I think it was $3.69 for a 1/16" by 1' by 3' piece!)
It cuts easily and is very flexible, so applying it with contact cement is easy. It takes longer to sand to shape, but the Fabricut I got from Ferree's works great. Fabricut is an emery cloth made like a window screen - many holes to prevent loading up of the grit.
Those of us guinea pigs who have tried this material on sopranos, basses, and eefers are pleased with the solid feel of the connections and the way lubricant lasts. None of the joints have been in use very long, but the informal word is that the stuff is long lived.
You know how the cork under the Ab/Eb key gets a hole pounded through it in no time by the peg that stops the key motion? Gasket Seal holds up well in that application.
Try it; you'll like it.
Ray
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Author: Hank Lehrer
Date: 2003-06-14 21:57
Hi Ray,
The cork you describe is just about exactly what I used and you are right, Neopreme does have a nice ring to it. And you are are also correct, the cork-type product is perfect in density, easy to work, and cheap. Just what a non-pro needs for those quick repairs. ![[up]](http://test.woodwind.org/clarinet/BBoard/smileys/smiley24.gif)
Several of the techs above have indicated that they still prefer the traditional cork but I'll continue to use this product and see what happens.
Thanks,
HRL
Post Edited (2003-06-14 23:02)
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Author: Gordon (NZ)
Date: 2003-06-15 00:45
I have been using this type of neoprene (or other binder) based 'agglomerated' cork on certain keys and linkages for at least 20 years. Later,, Yamaha and Yanagisawa started successfully using it too, and still do. In may of these locations it is far superior to natural cork.
However use in these locations should not be confused with the very different demands of a material used in tenon joints. Good natural cork is far superior for tenons, as I explained in my previous post. Some manufacturers' recent treatments even satisfactorily fill the holes. (Previous treatments did not!)
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