John et al,  I basically do the same thing except, instead of using
paint, I use PVC-E glue.  I prepare the wood, as usual, then apply
a medium coat of PVC-E glue.  In the glue, I draw a zigzag with thin
CA glue.  Position the keytop and press.  Hold it for a few seconds
and wipe off the excess PVC-E glue and let set. The CA will hold it
in place until the PVC-E dries.  No complaints so far.

Duaine Hechler
St. Louis, MO 63034
www.hechlerpianoandorgan.com