Soundboard cracks

[John W. McKone]

I've always wondered about this philosophy.

Shouldn't we try to approximate the hardness of the material that is being
replaced (i.e. spruce - a pretty darn soft wood) when doing this sort of
repair?  It seems to me that a flexible epoxy would best approximate the
hardness of soundboard material.

Hard, and therefore transparent glues make all kinds of sense for bridges,
but in my view, not for soundboards.

If, on the other hand, you want your repair to be as transparent as
possible, why not go the whole nine yards, and put in those maple shims -
then the entire repair - both glue and wood - would be more transparent.


>
>      It would seem to me that a fairly elastic glue would not be appropriate
>for a soundboard, as it would increase the damping.  This may be purely
>academic on a small crack or two,  but board-length cracks and separations
>may require enough material to make a difference.
>      Glues used in the wooden soundboards of musical instruments should be
>as acoustically "transparent" as possible. I believe that Steinway still uses
>hide glue to lay up their soundboards.
>      There is a   difference in the impedance of a joint that has been
>epoxied together, and one that has been glued with hot hide glue, or ( as
>Willis Snyder proposes), Resourcinol.
>     Also,  can you explain the use of "maple wedges" ,  as I would not
>expect maple and spruce to get along very well.
>
>Regards,
>Ed Foote
>Precision Piano Works
>Nashville, Tn.

John McKone, RPT
St. louis Park, Minnesota
(612) 280-8375
mckonejw@skypoint.com