Cellulose is the most abundant polymer on the planet. It's followed by lignin, the material that binds with cellulose to make wood hard (stop snickering.) and straw crunchy. Anything with a cell wall has lots and lots of cellulose, grasses, trees, fungus, even the lowliest of weeds is choc full o' cellulose. It's kind of awesome how the plant makes it. We all know that plants make sugar from the sun, right? Well, they take this sugar, make a few minor alterations, and then send it through a nifty little pump that right on the cell membrane. It's like a tiny little cellulose factory. Sugar goes in, cellulose comes out.
Anything nature can do, we can do better, right? Well, not better, but we can sort of do something like what cell walls do. We human folk use a lot of cotton, wood, soy, corn, and other plants. Inevitably, there will be waste and leftovers from the processing of these materials, and most of that will be cellulose of some kind or another. We take these waste products and cook them in lye, Sodium Hydroxide (NaOH) being its uptown name. This is the same chemical I use to clear butterfly butts. Carbon disulfide is added to help break down the cellulose. The end result is a viscous liquid goo that is spun into an acid bath which neutralizes the NaOH. This acid bath may contain sulfuric acid, sodium sulfate, glucose, zinc sulfate, and water. Sodium sulfate speeds up the precipitation of filaments, glucose softens the fibers, zinc sulfate strengthens the fibers, and water adds volume. What you end up with is Rayon, which was originally referred to as "artificial silk." Sometimes a dulling agent, such as titanium dioxide, is added if you're looking for something that's not quite so shiny as rayon. You can also add a bit of crimp to the fibers, either mechanically or by reducing the acid concentration. This aids in the spinning process, as anyone who's ever spun wool will know.
All of this information is as of the mid 1960's, so I'm not sure what advances or improvements have been made to the process. Some of those chemicals are pretty nasty in high concentrations, so this kind of processing is probably not the best for the environment. However, it's got to be better than polyester or acrylic. Not only are rayons softer, more absorbent, and wear better, but they're made from the waste of other manufacturing processes rather than petroleum.
Oh - I don't have a copy of the picture I drew for the Harlot. I'll be drawing more and different ones in the future, so perhaps I'll get one up here when I finish a new one. I'm learning how to dissect the reproductive parts out of the rest of the abdomen today, so hopefully I'll be able to get a clearer picture of all the different pieces parts.