> but I seem to recall Aaron saying that a space
> under the board is useful.  I can't find that latter conversation.

That was not my tip, but I did pick it up here on BEE-L.

Escape boards are the only way I use to clear supers (well, abandonment at
the height of a flow, but never when the bees show even the slightest
inclination to rob).  But based on the recommendation on BEE-L that the bees
exit more rapidly when there is more room than provided by the "standard"
escape board, I've come to always put an empty super over the brood boxes,
then the escape board over which I stack the supers I want vacated.
Unequivocally, the bees vacate faster when the extra space is provided.

Of course, users are cautioned to make ABSOLUTELY sure there are no cracks
of spaces ANYWHERE in the boxes above the escape board.  Duct tape (the
beekeepers friend) is a MUST if there are ANY spaces WHATSOEVER!  When in
doubt, duct tape.  If you miss a gap, YOUR BEES WON'T!  A robbing frenzy
will ensue!

Aaron Morris - thinking there's no escape like a roomy escape!