Viscose is considered to be a “semi-synthetic” fiber, as it is man-made, but it uses natural cellulose and a production process to achieve this interesting soft, lustrous fiber. Viscose, viscose rayon, and rayon are often used interchangeably. What started as “artificial silk” in the late 19th century became known as rayon in 1924.
Viscose/rayon is a versatile fiber and is widely claimed to have the same comfort properties as natural fibers, although the drape and slipperiness of rayon textiles are often more like nylon. It can imitate the feel and texture of silk, wool, cotton and linen. The fibers are easily dyed in a wide range of colors. Rayon fabrics are soft, smooth, cool, comfortable, and highly absorbent, but they do not insulate body heat, making them ideal for use in hot and humid climates, although also making their "hand" (feel) cool and sometimes almost slimy to the touch.
Production of this “artificial silk” is a multi-stage process which involves dissolving pulp with aqueous sodium hydroxide in the presence of carbon disulfide. This viscous solution is where the name viscous comes from. It is made from purified cellulose, primarily from wood pulp, which is chemically converted into a soluble compound. It is then dissolved and forced through a spinneret to produce filaments which are chemically solidified, resulting in synthetic fibers of nearly pure cellulose.
French scientist and industrialist Hilaire de Chardonnet (1838–1924)—who invented the first artificial textile fiber, artificial silk—created viscose. British scientists Charles Frederick Cross and Edward John Bevan took out British patent no. 8,700, "Improvements in Dissolving Cellulose and Allied Compounds" in May, 1892. In 1893 they formed the Viscose Syndicate to grant licences, and in 1896 formed the British Viscoid Co. Ltd. to exploit the process.
The use of viscose is declining. Instead, rayon may be manufactured using the Lyocell process, which uses N-methylmorpholine N-oxide as the solvent and produces little waste product, making it relatively eco-friendly.
Of course the primary use for viscose is clothing, but in the last decade, or so, it has become increasingly popular to incorporate viscose into the production of area rugs. In most cases it is used for effect to produce a "softer hand” or provide interesting highlights in wool rugs, but I have seen entire rugs made from viscose.
In either case one must be careful, as viscose does make rugs more difficult to clean, and viscose does not wear as well as wool. The other detail to be aware of, particularly with hand tufted rugs, is the stability of the hand tufted loops. Extra care must be taken to assure that the latex sealing the back of the rug is adequate and sufficient to properly seal these loops as viscose is very slippery and can easily be dislodged. This concern is not so great with hand knotted rugs as the pile fibers are anchored with a knot.