There are some varying terminologies here, but I have gone with the modern consensus on the name manufactured fibers. Formerly known as man-made fiber, manufactured fiber is defined as “any fiber derived by a process of manufacture from any substance which, at any point in the manufacturing process, is not a fiber.” (Textile Fiber Products Identification Act, 1960) Manufactured fibers include those regenerated from natural materials, synthetic fibers and inorganic fibers. Regenerated fibers include those based on cellulose (rayon, acetate, triacetate) and protein-based fibers (azlon). Synthetics include acrylic, modacrylic, nylon, olefin, polyester, spandex and vinyon. Inorganic fibers include ceramic, glass and metallic fibers. I think this timeline of manufactured fibers is something everyone working with vintage should know about. You can find it under Manufactured fibers in the Fabric Resource, or from the homepage dropdown menu. Timeline of first commercial use of manufactured fibers 1905 rayon in the U.K. 1910 rayon in the U.S. 1918 acetate in the U.K. (called celanese) 1924 acetate in the U.S. (trademarked Celanese) 1939 nylon 1939 vinyon 1950 acrylic 1953 polyester 1953 acetate and rayon given separate groupings by the U.S. Federal Trade Commission 1954 triacetate Late 50s Modal 1959 Spandex 1961 Olefin 1993 Lyocell Let me say this: I am no chemist. Understanding the processes used in creating manufactured fibers such as rayon, nylon and polyester was an interesting challenge for me. Having read, then read again (and again) about the invention and creation of these fibers, they finally stuck with me and I was able to present them in what I hope is understandable detail. I hope it is even a little interesting!