Need to call myth busters on the swelling cotton wick. Many, if not everybody, says wick expands when wet. I went as far as laying cotton wicks on a ruler. Cotton ball wicks and cotton yarn. Drenched them in VG. They had zero visible expansion after 2 days of soaking.
Silica expands, Cotton does not. I think the thought is to prevent wick builders from overstuffing their coils with wick that is too dense. It is a balancing act of getting enough cotton to keep the coil going with not obstructing the flow of the juice. I use organic cotton balls from Walgreens by the way, I never boil them and they taste great right out of the 4 dollar bag.