Although not a true synthetic, Rayon is the first man-made fibre. It's made from naturally occurring cellulose (usually from specially processed wood pulp). Because of the chemical processes involved in its production it is classed as a semi-synthetic or artificial fibre, and is generally considered the precursor to all true synthetic fibres.
Rayon can claim a heritage dating back to the 1850s, when Swiss chemist Georges Audemars invented the first crude artificial silk by dipping a needle into a solution of mulberry bark pulp and gummy rubber to make threads. Other chemists developed further techniques over the next few decades, but none were efficient enough to make the new fibre a financially viable alternative to real silk.
In 1894, British inventor Charles Cross, together with Edward Bevan and Clayton Beadle, patented a practical method of making artificial silk. They named their product "viscose" because their processing of the cellulose gave a highly viscous solution, which was then passed through a spinneret to form fine filaments (the scientifically minded can read a more detailed description of the manufacturing process). This chemical-intensive process is not very environmentally sound, unfortunately, though steps have been made in modern production to reduce the impact.
An alternative method of processing natural cellulose into a man-made fibre using acetone was developed by Swiss brothers, Doctors Camille and Henri Dreyfus. In 1905, Camille and Henri developed a commercial process to manufacture cellulose acetate. The brothers initially focused on cellulose acetate film, which was then widely used in celluloid plastics and film. By 1913, Camille and Henri's studies and experiments had produced excellent laboratory samples of continuous filament acetate yarn. In 1918 acetate (a.k.a. cellulose acetate or acetate rayon) fibre was first manufactured in quantity at the British Celanese plant in Derbyshire, England.
The advert above is from a 1915 magazine, and although I can't be sure, I believe this "Opaline" is a trade name for an early rayon fabric.
The first commercial viscose rayon was produced in the UK by Courtaulds in 1905, and in America in 1910 by the American Viscose Company. DuPont Chemicals acquired the rights to the process in the 1920s and quickly turned rayon (The term "rayon" was first used in around 1924) into a household name.
Artificial Silk stockings, 1925
Celanese (acetate rayon) fabrics in Sears & Roebuck, 1929
There are two varieties of viscose rayon fibre. Filament rayon is produced in the form of a continuous thread and can be used for fabrics to resemble silk. Spun rayon consists of short filaments twisted (spun) together into a yarn similar to cotton or linen, and is turned into fabrics to resemble these.
By the 1930s rayon was available in a profusion of different fabrics - plain satin, shadow print satin, crepes, velvet, Jacquard, taffeta, shantung, chamois, sharkskin, pique, boucle, gabardine, chiffon, voile, faille - rayon could do anything the natural fibres could.
Courtaulds Rayon advert, 1938
Rayon in both filament and spun forms has a beautiful soft drape, which helped cement its popularity in the drape-loving 1930s through the early 40s Swing era.
During the war Rayon was one of the Utility fabrics available through cloth rationing.
Acetate rayon is particularly suited to satins and taffetas, so really came into its own in the 1950s when fabrics with more body were required for the full-skirted silhouette of Dior's New Look.
Rayon is the most absorbent of all cellulose fibers, even more so than cotton and linen. Because of this, rayon absorbs perspiration and allows it to evaporate away from the skin, making it an excellent summer fabric. Its high absorbency applies equally to dyes, allowing beautiful, deep, rich colours.
Rayon is a good conductor and poor insulator, furthering its usefulness in hot climates.
It loses a great deal of strength when wet. Because of this it must be handled carefully when washed, and it is also more prone to stretching and shrinkage than cotton. Spun Viscose rayon fabrics shrink more with repeated laundering than fabrics made of the filament yarns.
Rayon lacks the elasticity and resilience of wool and silk and tends to crease easily.
Fiber Identification (information from swicofil.com)
In the burning test, rayon most resembles cotton. It ignites rapidly, sometimes even faster than cotton, burning with a large, bright, yellow flame. Burnt rayon leaves an odour like burnt paper, similar to cotton. The ash is also like cotton: light and feathery gray, which disintegrates rapidly.
In the feeling test, rayon is more difficult to identify. The variety of processes, modifications of technique and various treatments can make rayon look and feel like silk, cotton, wool or linen. In general, however, rayon has the smooth felling of silk. It is slippery because of the smoothness of the filaments, and has an almost brittle-feeling quality due to the fiber's inelasticity.
The breaking test can differentiate between rayon, cotton and linen yarns. Because of its inelasticity, rayon will tend to break shortly, with a short, uneven breaking pattern. It is even easier to distinguish when wet, as it breaks very easily then.
Continue reading: Nylon.