Plant Fibers – Stuff of Paper, Ropes, and Cloth
Investigating Plant Fibers as Commercial Products
Sep 3, 2009
Plant fibers are among the most useful of plant materials. Humans have relied on them for millennia to make cloth, rope, paper, baskets, and numerous other articles.
Classifying and Extracting Fibers
Fibers can be classified according to their use. Those used to weave cloth are known as textile fibers; cordage fibers are used in making rope, and filling fibers are used as stuffing in upholstery and mattresses.
Various methods are used to extract fibers from the source material. The fibers may be separated mechanically by ginning, in which machines tear the fibers loose.
Many soft fibers are extracted through retting, a process that uses bacterial action to degrade away the tissues, leaving the tough fiber strands intact. Hard fibers are obtained by decortification, in which unwanted tissues are scraped away by hand or machine.
The most commercially important fibers are cotton, linen, ramie, jute, hemp, and sisal.
Cotton: The King of Fibers. Cotton is a shrubby plant with lobed leaves. In tropical climates, most species are perennials, but in temperate zones they are grown as annuals. The fruit of cotton is a capsule (known commercially as a boll), and when it splits open along five seams, reveals a white mass of fibers. The fibers are hairs that extend from the seed coats of each of the ten or so seeds in every fruit. As many as 20,000 seed hairs may grow from a single seed.
Cotton bolls were originally picked by hand, a back-breaking and labor-intensive process. Today, however, this chore is performed by machines.
The harvested bolls are sent to a gin which is essentially a roller studded with spikes and covered by a metal mesh. The spikes draw in the fibers but the seeds do not pass through the mesh and are left behind.
The ginned fibers are packed into large bales and graded for quality. The bales are shipped to the appropriate manufacturer where the fibers are straightened (carded) and then sorted into parallel bundles of similar size (combed) in preparation for spinning into yarn or weaving into cloth. Cotton is usually bleached in a chlorine solution to remove the natural colors. Chemical dyes may then be applied to change the color of the yarn or cloth.
Linen: The First Fiber. Linen, derived from the stem fibers of the flax plant, is the oldest plant fiber used to make cloth. Today linen accounts for only 2% of the world’s textile production. The leading areas of flax cultivation in modern times are the republics of the former Soviet Union, the People’s Republic of China, and western Europe.
The flax plant grows with straight slender stems that support gray leaves and bell-shaped flowers and it is this stem that produces the fibers used to make linen. Two types of flax are grown commercially: one for its seed (linseed oil) and one for its fiber.
Flax is harvested after 100 days when the stems are a golden color by pulling the plant up by the roots from the ground, either by hand or machine. Gathered into bundles, the harvested stems are stood upright in the field to dry. Next, the seed heads are removed in a process called rippling by pulling the plants through a comb or special threshing machine.
The fibers are then retted (from the Dutch word roten, meaning to “rot”.) by employing microbial action to digest away the outer part of the stem. After retting, the fibers are dried in the sun or a kiln and then sent through machines that crush the dried flax. The freed fibers are hackled (combed) to separate the short fibers (known as tow) from the longer fibers (known as line).
Ramie: A Useful Member of the Nettle Family. Ramie is a perennial shrub and a member of the nettle family (known for their prickly and irritating leaves). Also called China grass, it has been cultivated for centuries in several Asian countries.
Ramie stalks are first cut and then the bark is beaten or peeled away. After bleaching by sun drying, a bath of caustic soda removes pectins and waxes freeing the long but brittle fibers.
Jute: Best Left Natural. Jute fibers, obtained from a species in the linden family native to Asia where it thrives in the monsoon conditions of the wet tropics, are used to make burlap, ropes, wall coverings, carpet backing, upholstery lining, and inexpensive clothing.
The fibers vary in color from yellow to brown and are difficult to bleach. For that reason, many jute fabrics are in natural colors.
Hemp: A Better Use. Hemp comes from the marijuana plant, more often associated with drugs than fabrics. Hemp fibers are used primarily to make industrial fabrics like canvas (the word is derived from part of the scientific name for marijuana, Cannabis.), ropes, and twines.
Sisal: Fiber from the Desert. Sisal comes from the desert Agave plant. Native to Central America, the fibers of this plant are used to make rope, string, and floor mats.
From cloth to ropes and paper to drapes, plant fibers impact the daily existence of every person on the planet.
 |
