When drying a screen you must dry the screen with the "print side" facing the floor and the "squeegee side" facing the ceiling. Exactly as it is when you print with it.
Reason: Gravity forces the emulsion to the proper side (print side) leaving the heaviest layer on the proper side of the mesh. This improves screen making, reduces exposure time, increases the stencil well which leads to better ink coverage and a lot more.
Fact: the mesh layer between the emulsion layers slows down light waves and restricts their ability to expose emulsion so an improperly dried screen that has the heaviest emulsion layer on the wrong side (squeegee side) will not capture detail or wash out properly. The first sign of this problem is the need to increase exposure time and the loss of fine detail; not to mention under-exposed (slimy) emulsion that washes down the drain.