I recall posts that referred to recrowning soundboards. The
procedure I've used when repairing cracks has been to cover the piano
with moving blankets and, using a heater under the piano, drying out
the piano for several days until the crack starts to open up showing
fresh wood. (A magnifying glass helps.) This means the piano is now
dryer than it has ever been.
Then wedge the soundboard up to restore crown and shim or epoxy the
cracks. After moisture is reabsorbed the shims or epoxy will be
clamped in place and some of the crown will remain.
My question is: Is there other ways to do this? What are others
doing to restore crown?