Rayon is made with a batch of nasty stuff, the theory of safety for wicking is that all these chemicals are removed in the processing for the end result. I just don't know about that, nobody has tested the Rayon for chemical residues left over, that I could find, or quantify what levels are meaningul or not.
You can find ton of tree-hugger sites that tell you never to wear the stuff because it will make you sick....likely over zealous....or they could be hyper sensitive, or convinced themselves they are hyper sensitive.
http://www.ilo.org/oshenc/part-xiv/textile-goods-industry/item/883-viscose-rayon That is Cellucotton
Rats inhaling Rayon in 1969
http://www.tandfonline.com/doi/abs/10.1080/00039896.1969.10666904#preview
MSDS on Rayon.
http://www.carbatec.com.au/pdf/manual/MSDS RAYON.pdf Says INCOMPATIBILITY WITH: Avoid contact with strong oxidants, perchloric acids, nitrates. Does that mean anything to vaping, I don't know. That MSDS is different that the one I saw circulating around.
Boiling is not going to remove the chemicals, it might lesson them, or it might just fuse them in, I have not idea. The Chines dog chicken Jerky snacks that killed thousand of dogs, was Irradiated (real Nuclear Nuking, not microwave nuking), so all the living things virus and bacteria were killed, but the chemicals remained.
Does Rayon taste all that much better....than something that is not manufactured with 10 toxic chemicals. Don't know, and I won't.
Rayon is a calculated risk to try, I am pretty sure I will opt out of the beta tester program.
It might be totally safe, but that weird taste on the first hits by some reviewers, means some nasty whatevers are being given off. Its not burning rubber grommets they are tasting.
I looked into the green version of Rayon, which is Lyocell or brand name Tencel, it definitely uses way less toxic stuff in the manufacturing, but you end up with nano-fibers. Sounds great Nano is a buzzword. But the problem with this alternative to Rayon is Nano stuff is so small, you can not get it out if it goes into something.....like a Cell of your body in your lungs. Nano so small it enters Cells, and I am sure that Nano whatever, is going to be carried up in steam. After how long or does it matter.....to me it doesn't I won't vape anything Nano-particle sized, the research will be in in about 10 more years.
But Nano does kill factory workers in China, from inhalation, and the Lyocell Rayon is the near same size of Nano-ness. Is that science, no, the lab-coats will need to start killing some rats, when they get funding and figure out how to test the Nano stuff on animals without effecting the lab workers.....and that Nano stuff is going to fly right through a Lab-worker respirator.
These two links combined are enough for me to say no to Lyocell Rayon
http://www.motleygreen.com/beta/article-details-nano-texties-facts-behind-the-fabric-58
http://nano.foe.org.au/node/350