Report on my cotton ball (bunny ball) wick in my bottom coil Pheonix/Ce3 XL I made last night, for those not familiar with the ce3 bottom coil. they use a vacuum in the tank combined with partial obstruction of the hole by the wick to prevent the liquid from just running past the wick and leaking, as you vape small air bubbles come past the wick into the tank breaking the vacuum in the tank therefore letting fluid out onto the wick and coil but just enough to wet the coil and no more, cotton balls have no weave or other structure to keep them together, less structure than even gauze, also my wick was oversized and as soon as the liquid hit them where the wick exits the holes into the tank pretty much exploded into a jiant spread out tufts, I think this obstructed the hole too much, restricting air from coming into the tank past the wick creating too much vacuum locking liquid in the tank, I would sometimes get the "clothes dryer" taste, I have determined this is a cotton dry hit, its very mellow compared to a silica dry hit, very strong primer puffs would get the air bubbles out and add enough fluid to the wick to get rid of the "clothes dryer" taste for a while.
Today I picked up 710 yards

(smallest i could get), of white
Bernat Handicrafter Cotton yarn , it is marked as medium #4, made in Canada with cotton imported from the US, it would have been nice to get a smaller size and to get organic non bleached natural cotton but i could not find any locally, I boiled 16' of it and got the same clothes dryer/hot cotton smell while it boils, I have so far made 2 cotton wicked ce3s with this stuff and it is working well, learning from my cotton ball tuft problem I kicked the wick ends to the side as they enter the tank, this leaves access for air to come in, the first few vapes had a slight dishrag taste I have heard talked about in this thread, never got that with the cotton balls, I have learned to just take the 10 or so short non inhale puffs to get them going. after that I have no detectable flavor at all just clean e-juice, no dry hits or flooding with this wick, just clean vape,
one thing I have noticed is that the range of acceptable vape voltage is much wider on cotton than silica, with silica to little voltage no vapor, to much and nasty dry hits, with cotton too low a voltage makes weak but usable vapor too high and flavor is muted but still usable, the "weirdo" flammable cotton wick is surprisingly difficult to burn as long as it is wet, very high voltages are possible, I have gone to 9 volts on a 5 ohm coil, 16 watts!, vapor is very strong, flavor is gone but not burnt like I would expect on silica. I have a 4.5 ohm joytech atomizer that does not like to go over 7, nasty dry hit.
that same 5 ohm coil can make some vapor at 3.7v, yea its very weak vapor and its takes a long pull to get a vape but it still producing, silica cannot do that it would just be air.
I made one 2.5 ohm for my ego batts a bit weak but quite usable, I think this wick is a bit to large in diameter for the 3.4v 2.5 ohm setup, going to try for 2.0 ohms next,