Thought I'd share my experience thus far. Been using the 44060 box of rayon with a magma and kayfun for a couple days now and am sold. First started just like cotton, same wick length etc, nothing special and it worked fine in both devices, but then a few million pages ago in this thread I saw mention of the tail thinning so I tried that and am VERY happy. So happy that I thought I'd try something with the magma I haven't done, and that's having only one tail per wick going into the
juice well on the theory that less material in the juice well, the more
e-liquid it can hold.
Here's a picture of my magma today, after
vaping mint chocolate chip all day yesterday on it. I took a little more rayon than needed, twisted an end, and tried to tug it through the coil but wont go. So I string cheese some off until it does slide in (without twisting the wick), and the right amount seems to be where you I can feel the material actually gripping the coil as you slide it through. It's not that it's too thick, but I can actually feel the friction of the material gripping the coil. Snipped one side, then fanned out the other, and thinned it so it comes to a tip, wet it and got into the juice well. Performed great, and noticed for the first time I wasn't having constant issues of juice leaking out the air holes like I normally do. Maybe it's a fluke, I don't know, but the default design causes juice to pool up on the flat deck and any refilling normally causes me to have to blow out juice from the air holes, so make of that what you want. Today, the back wick is a bit gunky and still partially saturated, noticed part of the short tail was contacting the deck which probably altered it's wicking properties (that side of the deck had juice pooled on it, the front side did not, so I'm adjusting it so nothing makes contact with the deck or wall, will see how that goes).
As for my kayfun (sorry, dont have a picture), I had an interesting experience. Typical standard microcoil kayfun setup on that 45 degree angle. My first rayon wick was no thinning of the tails, and just like a normal cotton setup, saturated and stuck into the back of the deck away from the juice channels. Wicked just fine, never a dry hit. But, after hearing about the thinning concept and doing the magma, I redid the kayfun again yesterday afternoon with thinned tails, assembled and... was often getting dry hits. Slept on it, then today I rewicked it again with thin tails, but this time I attached the chimney without the top so I can see what it looked like after screwing it on, and what happened was the curved shoulders would literally grip the chimney and shift as it screwed on causing it to block off the juice channels. Using my small screwdriver, I re-positioned them where they belong and it's performing like a true monster.
So if anyone's having issues with dry hits on a kayfun, pay attention to the wick AFTER putting the chimney on, you may have a similar issue to what I did. As for the tails, I fan them vertically then thin it so the longest strands of the tail are on the bottom basically, saturate it, then work it a bit with my screwdriver so that it makes a nice wide-angle curve (which easily makes contact with the chimney wall, which is what causes the complication I had above when screwing in the chimney, and after re-adjustment it will still make contact along the wall, but it works so whatever). Interesting thing is, as I work the tail into a clean curve, it flattens a bit so it's no longer circular but more like a sheet of strands, which probably helps contribute to it forming a nice curve instead of a sharp bend. All I can say is, it wicks great and couldn't be happier.
Far as the health drama thought I'd throw in my 2 cents. I don't know how safe vaping with cotton is anymore than rayon (or vaping in general), but the risks are more likely inherited if you BURN the material instead the juice (not that I know how safe the juice vapor is either). I noticed on my dripper that instead of getting the cotton dry-hit "time to drip" hit (me and cotton was always either good hit, or dry hit, never a drop off inbetween, so it was inevitable), the rayon diminishes in flavor signaling me BEFORE I reached a dry hit. I feel safer with rayon because I actually get more dry hits with cotton, which I'm inclined to believe is the health risk part. That, and the common gunk buildup from cotton is probably not a good thing to be inhaling either, wouldn't be surprised if that buildup is more dangerous than the juice or wicking material. I prefer synthetic to natural anyways since it means a more scientific process goes into producing it (I avoid organic products of all kind, to give you some insight into my character). Just cuz something's more natural, doesn't tell me squat about it being better in any way. Besides, there's nothing natural about my e-juice, nicotine, batteries, mod, kanthal, or anything else in the vaping process. I also live off a DIY soylent instead of eating food the way nature intended. Yay science! Until I see studies that can CONFIRM the risks I've chosen to take, allowing me to reassess the situation, I will continue on at my own discretion. tl;dr: keep your wicks wet.