Warped grand piano lid--conjecture!

[JIMRPT@AOL.COM]

Brian;
 Having been stored for a while it is very probable that the 'warp' in your 
lid was caused by moisture................possible scenario:

The thingee was stored on its side, on a board, and the top was touching a 
pad that was touching the floor..this provided a path for the moisture to 
soak the edge of the board.  Possibly the edge of the board was soaking up 
the moisture and providing a path to the rest of the cored panel...ergo the 
warp on that edge only.

Two possibilities from this point:
1. The edge of the board warped because the side in contact with the pad 
released moisture more quickly than the inside/underside which had no contact 
with a wicking surface like the pad. 
2. The core of the top is fabricated from planks rather than strips; (3" wide 
or wider as opposed to less than three inches wide) as planks are more prone 
to warping than are counter grain laid strips and the warping is confined to 
one core plank.

  These are just SWAGs since you didn't give us much info to go on but if 
moisture is the culprit all the weighting in the world is not gonna 
straighten your board/top unless you also use moisture to help warp it back 
into place. (are there any signs of water absortion?, i.e., loose 
finish/white marks/ veneer edge out of place?  Whatever you do don't be in a 
hurry and don't worry about having to reglue some veneer..it ain't that hard 
to do :-)
Jim Bryant (FL)