 The Clarinet BBoard
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Author: AAAClarinet
Date: 2013-12-11 06:08
Sadly my Leblanc L 200 just cracked for the second time in a month. The crack goes from the top of the top join through two trill key tone holes. This crack is about 1/4 inch from the last crack, which was repaired about two weeks ago. The clarinet was in my hand when it cracked, it was loud and emotionally painful. Neither crack went through to the bore. Oh well, just have to send it back to the shop. Just thought I'd share...
AAAClarinet
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Author: SteveG_CT
Date: 2013-12-11 18:17
Was this a recently acquired instrument and did the previous owner live in an area with a significantly different climate?
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Author: Caroline Smale
Date: 2013-12-11 19:41
Was it just glued. pinned, or banded?
I would consider a carbon fibre band (or several) is only reliable method in these circumstances.
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Author: AAAClarinet
Date: 2013-12-11 20:14
SteveG: The instrument was bought on auction by a friend, I don't know where it came from. It was in the mountains for a few months before I brought it to the valley.
Cyclopathic: yes, same clarinet.
Norman: I believe it was pinned.
AAAClarinet
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Author: Caroline Smale
Date: 2013-12-11 21:31
Apologies if this bit of advice is rather late now...
however the most absorbent part of any wood is the end grain - and when a tone hole is drilled through wood it inevitably exposes end grain.
So water logging in a tone hole means that water is sitting right on this grain and if it is a normally closed tone hole then there is very limited scope for the water to evaporate quickly.
As a matter of principle on a new (or long time unused) clarinet it is highly advised to get this water out of the holes pronto.
The 2 trill holes and the throat A/Ab are particularly effected.
My technique after swabbing and separating the joints is to stop the lower end of top joint with hand, close all finger holes as normal and blow firmly into top end whilst opening the trill, A and Ab keys individually to blast any water lodged there out.
Being fussy I put a bit of absorbent towel between tone hole and pad when doing this but it's not essential.
I still do this after each play session even on my 50 year old Leblancs, at least for the 2 trill keys.
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Author: cyclopathic
Date: 2013-12-12 20:03
yes it is due to wood being overly dry/too much water exposure. Too much playing too soon.
On old dried out horns it is good idea to take keys off, superglue the cracks, then oil horn. Oil starting from outside and then both bore and outside for couple weeks until oil does not get absorbed over several days. Then put it together and start gradually break them in.
wood does not absorb oil as quick as water, so less localized stress/less cracking. And oil in wood will reduce water absorption, less chances of cracking when you start playing.
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Author: BobD
Date: 2013-12-12 20:54
A thought: When wood is being stressed by any means it will resist the stress until the weakest area cracks. This crack may not relieve all of the stress and if the clarinet is pinned or banded the remaining stress may cause the next weakest area to crack. Sorry to hear of your problem.
Bob Draznik
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Author: cyclopathic
Date: 2013-12-13 11:42
@BobD
the reasons mpingo became the wood of choice is b/c of the availability, stability, low shrinkage rates, tight grain with small pores and oil content. Basically what was at hand and had ability to resist wetting/drying cycles.
Never the less when any wood shrinks it shrinks tangentially more, so dried wood has more stress and tendency to crack on outside. Especially if you wet if from inside.
You can reduce chances of cracking by restoring wood to more or less original form (oiling), and sealing open grain (oiling, waxing, polishing, etc). Oiling on outside swells external layers of wood and reduces stress caused by tangential shrinkage. Sometimes you don't need to do anything to cracks I had seen cracks as big as .5mm close from oiling.
mpingo shrinkage information
Radial: 2.9%, Tangential: 4.8%, Volumetric: 7.7%, T/R Ratio: 1.7
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Author: BobD
Date: 2013-12-13 18:23
Radial crack due to circumferential(hoop) stress......
Bob Draznik
Post Edited (2013-12-13 18:37)
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