Only trick is to make SURE you fill the channels or right behind the channels just right for your wicking material. With mesh, its making a roll just big enough to fully fill the slots and get properly mushed in by the chimney cap (and without using the chimney O-ring). If that's done just right, it virtually will never piss itself if you fill it properly (close off AFC, hold the chimney tube with a finger, fill through the fill hole, close the fill hole, flip, and open AFC and release finger at about the same time).
With cotton/ekowool, you really just need to make sure you have enough a little bit in and lots right behind the channels without packing it too tight so it can still block excess and wick properly.
With cotton/ekowool, you really just need to make sure you have enough a little bit in and lots right behind the channels without packing it too tight so it can still block excess and wick properly.