You probably know what rayon fabric looks or feels like—the best Hawaiian shirts (and much of 1980s fashion) were made of it. What’s fascinating about rayon is that it is not really a synthetic or a natural fiber. Rayon is a chemically modified cellulose polymer, first prepared in the 1850s. While there have been a number of ways of preparing this “artificial silk,” the Viscose method led to the first commercial production of rayon. This method treated cellulose with a combination of sodium hydroxide and carbon disulfide as indicated below.