Klarinet Archive - Posting 000770.txt from 1999/10

From: Schaffner Thomas <schaffne@-----.ch>
Subj: Re: [kl] Cracks: pinning vs. filling
Date: Tue, 26 Oct 1999 03:02:24 -0400

As has been mentionned before on this list a mixture of grenadilla wood-dust
with a very liquid epoxy resin (the kind used by hobbyists as "cold" enamel,
available in art shops) may be used to fill narrow cracks. The mixture might
have to be injected with some pressure to make sure the crack is completely
filled (i.e. using a syringe). There is some risk though, the crack occurred
because the wood contracted (by drying out on the outer side of the
instrument) or expanded (by picking up humidity from within), probably
because of a flaw in the wood. Both conditions are likely to recur
(dry/humid seasons). If now the resin occupies the space opened by the crack
new tension develops when the instrument is again drying out or reexposed to
humidity and thus a new crack could develop at an other place. I have an
instrument that had to be repaired twice this way but has been stable ever
since. An experienced repairman will expand the crack before filling and
will let it contract again before the resin hardens completely by changing
the humidity. The result is very satisfying esthetically and there are no
more leaks. Wide cracks will probably also need pinning.
Cordially, Thomas Schaffner

Anne C Benassi <acb@-----.is> wrote:
re: [kl] Cracks: pinning vs. filling

Can anyone enlighten me on the benefits of pinning vs. filling cracks?
Virtually everyone on the list who has mentioned crack repair has
mentioned pinning, but my local repairman prefers, I believe, to fill
them. Comments?

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