In message <000f01c27075$dc6cd640$f27dfea9@allen>, Allen Dick
<[log in to unmask]> writes
>I've concluded that the most practical escape boards for my purposes are
>the Quebec board, or a variation of that design.  However, I seem to recall
>discussion of the need -- to get the best performance -- of making a rim on
>either the top or the bottom of the board that is larger than the 3/8" rims
>that are typically sold.
I recall discussion in one of the Canadian Newsletters (Red River) some
years ago showing that space immediately under the clearer board was
essential to allow the bees getting through if there was a mad rush to
have space to gather. I have purchased and made myself clearer boards of
the Canadian, New Zealand and other designs with a good 25mm (1") rim
under them.  I had not come across the idea of enlarged space above the
boards and will add this to mine. Otherwise, using bottom bee space, as
many of us seem to do in the UK, the standard design actually adds
another bee space under the frames above the clearer board. I came
across a design of escape using a line of flaps on the lines of spray
entrances. This seems to give a wide space for the bees to get through
and definitely keeps them from finding their way back - so long as a
flap is not propolised!!
--
James Kilty