Soundboard crack, weird

[John Hartman]

JIMRPT@aol.com wrote:
> 
> Del, List;
>   I have just taken a plate out of a S&S model 'S'.  The sounding board is
> fairly intact and has only two loose ribs, in the usual locations.
>   BUT.............on the bass end behind the dampers there is a crack that
> runs.... across.... the grain it starts at the belly board and goes about 16
> inches up the board.  The grain in this panel is straight and for the first 4
> inches the crack follows the grain, then it starts its curve across 5 grain
> lines and ends up about 5/16ths (8mm?) off the straight line.  There is no
> evidence of trauma, or impact.
> Has me puzzled, any thoughts ?
> Jim Bryant (FL)Jim,

This type of crack may be caused by a wood defect referred to as shakes. 
Since I  purchase spruce for soundboards I have become familiar with the 
many defects. They are very fine cracks that follow the grain but can and 
often do travel diagonally for short distances. I have been told that 
this kind of crack is caused by careless felling of the timber, allowing 
the bole to fall on rocks or other obstacles. 

Shakes can be very hard to find. They are not easily seen even in the 
planed boards. It is conceivable that the manufacturer did not see the 
defect. It has opened up, dirt has fallen in and now the defect is 
visible. Earlier in my soundboard career I purchased panels that 
occasionally had a shake in one of the boards. The problem is 
particularly prevalent in eastern spruce. 

John Hartman RPT