Restoring crown in old soundboards - new cracks

[Roger Jolly]

>
>And yes almost all the shims that have been made 10 to 15 years ago
>are opening again on almost all the instruments I see.
>
>best Regards
>
>Isaac OLEG

Hi Isaac,
                Do you dry down the board and shims just prior to 
installation?  We use two 50Watt damp chaser rods hanging about 30cms below 
the board, the pre fitted shims are left on top of the board to also dry 
for  3 or4 days,  the piano is draped in moving blankets.   We clamp the 
shims in position with go bars.
     Some times we will create another crack with the drying down.

Regards Roger