I never had dust cone in the joint of a filter, my only ever dust issue
was around the part where the filter connected with the carb tube.
Vaseline was my friend and cure.
But before that I put some breathable material over the hole in the
bottom of the carb box, that stopped the fines right away, the Vaseline
was the second line of defence.
All my filters I blow out from the inside with low pressure air, so no
need to split them, I think for people who split them then the joint
will eventually need a lick of grease or Vaseline.