Various types of wire mesh have been used to cause
some of the pellets of pollen to become detached. The type
illustrated at left has every junction resistance welded at a pitch
of 5 mm, so that the mesh is rigid and each hole has it's
dimensions controlled as no movement of individual strands is
Woven Wire screens can be used, but they have the
disadvantage that narrow strips, such as in required for vertical
stripping screens. These are easily corrupted in handling with some
gaps becoming too narrow and others becoming wider than required,
reducing the effectiveness.
Round holes in plastic sheet are also popular as is shown
in the right hand picture. Two colours are shown that are common in
Europe (I guess Polish or Czech manufacture), but I have also seen
grey and white, as well as aluminium versions.
My personal favourite (and probably the most effective) is
a plastic sheet one millimetre thick that has a number of star shaped
holes punched in it. Simply due to the action of a bee climbing
through these holes means that many pellets are removed.
The type that I use is 55 mm wide and 342 mm long,
I drill some 3 mm diameter fixing holes along each edge and then
use "System Zero" Screws
to attach to 6 mm (or 9 mm) plywood panels that have been
cut out to take them. See
"Rational" Pollen Stripping Screen.
The star shaped stripping screen started life as a hole with
four small slots around the bottom part of the circumference. (bees
legs are underneath and the original usage was vertical).
The snag with this arrangement is that the punch and die
suffered side thrust during the punching action, due to uneven
resistance and instead of designing a 'shear proof' punch and die it
was decided to make the slots radiate in all directions and thus even
out the stress. Hence the star shape... Because a star is even in all
directions horizontal placement of the screens became sensible.
Update... 29 Sept 2002. After I wrote the note above I found
an old and faded black and white photograph that shows the original
aluminium stripping screens... I was wrong about there being four
slots, there were actually five and they were arranged as per the
diagram at right.
The photograph itself was too poor to reproduce and so I
have drawn a facsimile of it to show how it was used. The mesh that
the pellets fall through should be 6 or 7 mesh, although I have
had success with 8 mesh. (Which was used, simply because it was
Written... 31 March 2001, Revised... 05 July 2002, Update... 29 Sept 2002