I had regular cotton balls kicking around the house, so I boiled them and have them in a baggie waiting to be used. I have wicked everything I've done so far with rayon. Actually, let me modify that statement. Before my wire showed up, I re-wicked a kanger single coil head with cotton. Multiple times, couldn't get the density right. It either flooded or dry hit on me. Now I take rayon from Sally's and roll it lightly on my jeans until it's about the size of my coil, really twist the end so that I can thread it through and then pull it through until it feels right. I go for where it's snug since that's what people say works best for rayon. Not deforming/moving the coils snug, just where the coil is lightly hugging that delicious juice deliveryman. Trim it up and done.
The build I'm liking the most out of the few I've done so far is six wraps of 28 around a 2mm rod. It's reading about 1.2 on my Sig. It is polite at 10W and gets to be awesome at 20. It might be the wicking I like more in that build as well. It's trimmed closer to the chimney on that one compared to the 1.8 build (8 wraps). I do take the outer sheath off of the head and put a flavor wick on top to prevent flooding. It looks like a weird modification of the old single coil heads.
I think for the Aspire coils, I'll have to take way more time to get an even strand of consistent width so that I can wrap it around that BVC.