Bast fibers, also commonly referred to as skin fibers, are natural plant-based fibers that grow within the stems of certain plants. Located in the inner bark, or phloem layer, of the stalk, these fibers can reach several feet in length. As one of the major natural vegetable fiber resources in the world, bast fiber plays an important role in the textile industry.
Most of the important bast fibers are obtained from plants cultivated in agriculture, including flax, ramie, jute, kenaf, and hemp. Because the valuable fibers are located in the phloem, it is necessary to separate them from the xylem and sometimes also from the epidermis. Minor fibers of historical interest but of little or no commercial importance include urena and nettle.
Bast fibers are generally thick and boast high tensile strength. They are usually processed for use in coarse textiles such as ropes, carpet yarn, traditional carpets, geotextiles, and hessian or burlap sacks. Beyond traditional textiles, they can also be used in composite technology industries manufacturing nonwoven mats, carpets, and composite boards for applications such as furniture materials and car door panels.
How Are Bast Fibers Processed?
Harvesting
Bast fibers come from the stem of the plant, positioned near the outer edge. Hand labor may be used to process bast fibers, and production has flourished in countries where labor is cheap. Since the fiber extends into the root, harvesting is done by pulling up the plant with mechanical pullers or cutting it close to the ground to keep the fiber as long as possible. Cut fibers are approximately 10% shorter than pulled fibers. After harvesting, the seeds are removed by pulling the plant through a machine in a process called rippling.
Retting
Bast fibers lie in bundles in the stem of the plant, just under the outer covering or bark. They are sealed together by a substance composed of pectins, waxes, and gums. To loosen the fibers so that they can be removed from the stalk, the pectin must be decomposed by a bacterial rotting process called retting.
Retting can be done in the fields through a method known as dew retting, or in stagnant ponds, pools, or tanks through water retting, where the temperature and bacterial count can be carefully controlled with special enzymes or with chemicals such as sodium hydroxide. Chemical retting is much faster than any other method; however, extra care must be taken during this process or the fiber can be irreversibly damaged. Retting can also create problems with water quality if the retting water is released directly into streams or lakes. Dew retting is preferred in many areas because of its minimal environmental impact. Fiber quality can be greatly impacted by whichever retting process is chosen.
Scutching and Hackling
After the stems have been rinsed and dried, the woody portion is removed by a mechanical process called scutching, which breaks or crushes the outer covering when the stalks are passed between fluted metal rollers. Most of the fibers are separated from one another, and the short and irregular fibers are then removed by hackling, or combing. This final step removes any remaining woody portion and arranges the fibers in a neat, parallel fashion.
Cottonizing
Because the processing of bast fibers is time-consuming and requires specialized machinery, researchers have developed ways of speeding up the process and minimizing the need for special equipment. Cottonizing reduces a bast fiber to a length similar to that of cotton, allowing these fibers to be processed on equipment designed for cotton. However, cottonized fibers may lack some of their more traditional characteristics related to hand, luster, and durability. Flax, ramie, and hemp are bast fibers that are frequently cottonized.
It is also worth noting that bast fibers characteristically have thick-and-thin variations in their appearance when processed into yarns and fabrics. This occurs because fiber bundles are never completely separated into individual or primary fibers.
Flax Fiber
Flax, or linen, was probably the first plant stem, or bast, fibre used by man for making textiles. It is one of the oldest textile fibres in the world, and the earliest trace of its use dates back to ancient times. Linen fabrics were discovered in Egyptian tombs wrapped around the bodies of the pharaohs. Flax is obtained from the outer cover of the stem of Linum usitatissimum, an annual plant grown in many temperate and subtropical regions of the world.
Cultivated flax is of two types: one is grown for seed and the other for fibre production. Fibre flax is grown mainly in cool, wet temperate climates and cultivated widely in Europe, China, and Egypt. Flax fibre is soft, lustrous, flexible, and stronger than cotton fibre, although it is less elastic. It is used to produce woven and knitted fabrics with excellent health, hygienic, and aesthetic qualities. Linen fabrics absorb sweat, cool the body in hot weather, and do not collect electrostatic charge.
Traditionally, linen was used for tablecloths, bed linen, and upholstery fabrics. Today, flax fibre is also used for garments, geotextiles, automotive products, ropes, twine, and high-quality paper products. The term linen refers to fabric made from flax, but it is sometimes used loosely for fabrics of other fibers made of thick-and-thin yarns with a heavy body and crisp hand. Irish linen always refers to fabrics made from flax.
Flax Properties
The unique and desirable characteristics of flax are its body, strength, durability, low pilling and linting tendencies, pleasant hand, and thick-and-thin texture. The main limitations of flax are low resiliency and lack of elasticity. Most flax is produced in Canada, Russia, Belgium, and the Netherlands. Some flax is also grown in India, Pakistan, China, and Africa. The majority of flax grown in the United States is in the Dakotas and Minnesota, because it is a crop that matures rapidly under cool, short-season growing conditions.
Individual fiber cells, called ultimates, are spindle-shaped with pointed ends and a center lumen. The primary fiber of flax is long and narrow. Flax fibers can be identified microscopically by crosswise markings called nodes or joints that contribute to its flexibility. The nodes may appear slightly swollen, resembling the joints in a stalk of corn or bamboo. The fibers have a small central canal similar to the lumen in cotton. The cross section is many-sided or polygonal with rounded edges. Immature fibers are more oval in cross-section with a larger lumen.
Flax is similar to cotton in its chemical composition. Compared to cotton, flax has a longer polymer, a higher degree of polymerization, and greater orientation and crystallinity. Flax fibers are slightly grayish when dew retted and more yellow when water retted. Because flax has a more highly oriented molecular structure than cotton, it is stronger than cotton.
Short flax fibers are called tow; the long, combed, better-quality fibers are called line. Line fibers are ready for wet spinning into yarn. The tow fibers must be carded before dry spinning into yarns for heavier fabrics for interior textiles.
Flax Performance, Care, and Sustainability
Flax has quite pleasing, excellent aesthetics. It has a high natural luster that is softened by its irregular fiber bundles. Its luster can be increased by flattening yarns with pressure during finishing. Because flax has a higher degree of orientation and crystallinity and a larger fiber diameter than cotton, linen fabrics are stiffer in drape and harsher in hand. Finishes that wash and air blow the fabric produce softer and more drapeable fabrics.
Flax is strong for a natural fiber. It has high breaking tenacity when dry, and its strength increases when wet. Flax also has very low elongation. Elasticity is poor, and it is a stiff fiber. With poor elongation, elasticity, and stiffness, repeatedly folding a linen item in the same place will cause the fabric to break. The nodes contribute greatly to flexibility, but they are also the weakest part of the fiber. Flax has good flat abrasion resistance for a natural fiber because of its high orientation and crystallinity.
Flax has excellent comfort. With a high moisture regain, it is a good conductor of electricity with no static buildup. Flax is also a good conductor of heat, so it makes an excellent fabric for warm-weather wear. Flax has the same high specific gravity as cotton.
Linen fabrics can be dry-cleaned or machine-washed and bleached with chlorine bleaches. It is resistant to alkalis, organic solvents, and high temperatures. For upholstery and wall coverings, careful hot-water extraction cleaning is recommended to avoid shrinkage. Linen fabrics have low resiliency and often require pressing. They are more sunlight-resistant than cotton. Crease-resistant finishes are used on linen, but the resins may decrease fiber strength and abrasion resistance. The poor appearance retention, or wrinkling characteristics of linen, makes it easy to recognize. Linen fabrics must be stored dry; otherwise mildew will become a problem.
Flax has less of an environmental impact than cotton. The production of flax requires fewer agricultural chemicals like fertilizer and pesticides, and irrigation is seldom required. But the practice of pulling the plants during harvest in order to get longer fibers contributes to soil erosion. Removing the fiber from the stem requires significant amounts of water, but recycling is often used. Depending on the type of retting used, disposal of chemicals and contaminated water are other areas of concern. Changes in retting practices have occurred because of environmental issues. Dew and enzyme retting are more sustainable practices than water retting. Hand labor used in some areas where flax is produced needs to be monitored to avoid exploitation of workers.
Flax burns readily in a manner very similar to that of cotton. Fiber length is an easy way to differentiate between these two cellulosic fibers. Cotton is seldom more than a short staple fiber, while flax is almost always longer than that. However, cottonized flax will be more difficult to identify. Flax is also soluble in strong acids.
Uses of Linen
Linen is used in bed, table, and bath items, in other interior items for home and commercial use, in apparel, and in technical products. Linen fabrics are ideal for wallpaper and wall coverings because their irregular texture adds interest, hides nail holes or wall damage, and muffles noise. Linen fabrics are used in upholstery and window treatments because of their durability, interesting and soil-hiding textures, and versatility in fabrication and design.
Linen apparel includes items for warm-weather use, high fashion, casual, and professional wear. Technical products include luggage, bags, purses, and sewing thread.
Ramie Fiber
Ramie fiber, or China grass, comes from a plant in the nettle family. Like flax, the fibers are found in the outer layer of the stalk. A perennial shrub, the ramie plant grows in semitropical regions. At present, ramie growth and processing are concentrated in the Philippines, Brazil, and China. Hong Kong, Taiwan, Korea, and Japan process but do not grow ramie.
Ramie stalks are planted, and the fiber is harvested after the plant has matured. Several crops may be cut each year in suitable climates. After cutting the stems, the leaves of the plant are beaten off, the stems are split lengthwise, and the bark is stripped from them. This yields ribbons of bast that are soaked in water until the green outer layer can be scraped off. After drying, this substance, sometimes called China grass, is bundled and shipped.
Before spinning, the fiber must be retted out of the ribbons. Both dew and wet retting, similar to that used with flax, can be done. A chemical retting process that uses sodium hydroxide and an acid rinse has also been developed and is used in industrially developed countries.
Ramie has properties similar to flax but is stronger and more lustrous. It is the strongest of the natural fibers and the most crystalline. Like flax, it has fairly low resilience and flexibility and a high modulus. It is white in color, its absorbency is excellent, it dyes rapidly, and it has good resistance to attack by microorganisms. The commercial use of ramie had been limited by processing difficulties that made it expensive to produce. Until chemical retting became available, only hand methods could be employed to remove the fiber from the stem. Controlling fiber quality was also difficult. Researchers have developed controls for growth and processing that have made possible the production of uniform quality fibers.
Ramie is used alone or in blends. It is most frequently blended with cotton, linen, or polyester. Ramie fabrics are machine washable but require ironing and may shrink. If blended with adequate quantities of polyester or other synthetics, these fabrics will have easy-care characteristics and little shrinkage. The major use of ramie fabrics, especially ramie blends, in wearing apparel is in sweaters, suits, and pants. It is also used in table linens and fabrics for home furnishings. Ramie also shows how trade policies can influence fiber markets and change production patterns.
Jute Fiber
Jute fiber is taken from the stem of the jute plant. Successful cultivation of the plant requires fertile soil and a hot, moist climate. Jute is grown in India and Bangladesh and, to a lesser extent, in Thailand and other Southeast Asian countries. It is the most commercially important of the bast fibers.
Jute plants grow tall, and the stalks are cut just after the flowers begin to fade. Like other bast fibers, separation of the fiber requires retting. Many jute producers use chemical retting processes with chlorine compounds. After retting, the stems are broken and the fiber is removed.
Jute and other bast fibers such as kenaf and hemp are shorter than flax. The actual fibers in the plant stalk, called ultimate fibers, have aspect ratios that make them difficult to spin. Because the ultimate fibers are so short, jute is not processed to separate out individual fibers, but only to separate fiber bundles, which can be quite long. The fibers in the bundles are held together by lignin and other substances that act as glues.
Jute ranges in color from light to dark brown. Its strength is somewhat lower than that of other bast fibers, but it has similar bending properties. On exposure to air, jute becomes somewhat brittle. It absorbs moisture readily, resists deterioration by microorganisms more than some cellulosic fibers, and is weakened by exposure to sunlight.
Jute has long been in demand as a cheap, useful packaging material. Burlap is one of the major jute bagging fabrics. Jute has also traditionally been used for carpet backings and cordage. In recent years polypropylene, a manufactured fiber, has become a major competitor for jute in many of these uses. As a result, jute-producing countries have been looking for additional and innovative applications.
Some of these have been as geotextiles in erosion control, as a cheap replacement for cotton filling yarns in handwoven fabrics in India, and as reinforcement fiber in composite plastic structures. Continued competitive success for jute will depend on economical production to keep costs down and on marketing strategies. Recently, efforts have been made to promote jute for apparel and decorative household fabrics. One advantage jute enjoys is that spinning processes for the fiber are more developed than those for other bast fibers such as kenaf and hemp.
Kenaf Fiber
Kenaf fiber is also a bast fiber, similar to jute in that it is composed of short ultimate fibers that are separated from the stalk as fiber bundles. Botanically, it is related to both cotton and okra. Grown predominantly in Africa and India, kenaf has sparked renewed interest as an alternative crop in the South and West of the United States.
When harvested, the plant stems are decorticated to remove the inner part of the stalk, then retted to obtain the fiber bundles. Mechanical fiber properties are similar to those of jute, but kenaf is stronger. It is also whiter, more lustrous, and can be bleached and dyed more easily. While kenaf has a high moisture regain, it is not wet as quickly as cotton.
Traditionally, kenaf was used in making rope and twine, for which its high strength was important. Recent developments have focused on the use of these fibers in paper making because paper of kenaf fibers is smoother and whiter than that made from wood pulp. New methods for processing the kenaf stalks to obtain longer fibers have led to the production of nonwoven and woven textiles. For example, a nonwoven mat of kenaf fibers containing grass seeds is now marketed as a lawn starter. Apparel, wall coverings, and awning and tent fabrics have been constructed of kenaf and kenaf blends.
The woody core of the kenaf plant can be used for animal bedding, packing, and as an absorptive material for oil spill cleanup.
Hemp Fiber
The hemp plant, Cannabis sativa, is a member of the mulberry family and a type of marijuana plant. The fiber bundles come from the bast layer of the stem. Mature plants are cut off and spread on the ground, where they are left to dry for several days. Leaves and seeds are beaten off, and bundles or sheaves of hemp are formed after additional drying. Retting, breaking, and scutching complete the fiber extraction process.
Hemp fiber has high tensile strength comparable to that of linen. It has good absorbency but poor elasticity. In its chemical properties, hemp is similar to cotton and flax. The major uses of hemp are in the production of industrial fabrics, twine, and ropes because of its good tensile strength and high modulus that provide initial resistance to force.
Interest in apparel and household fabrics made from hemp, as well as craft items, has increased over the past decade. Designers have added fabrics containing hemp fibers to their lines, and it continues to appear in novelty uses. Legal status varies by country, but industrial hemp is often discussed as a fiber crop because it contains very little of the psychoactive substance found in drug-type cannabis.
Hibiscus Fiber
Hibiscus is from the same general botanical family as cotton, the Malvaceae family. The plant grows as a tall shrub in tropical and subtropical regions. While it is commercially grown and used for clarifying sugarcane juice, the waste material has been studied for its fiber potential.
As with other bast fibers, retting is required to extract the fiber from the plant stem. Hibiscus fiber can be bleached and has good fastness when dyed with direct dyes. The fiber is stronger than jute, with potential uses in bags, rugs, and some apparel items when used in blends.
Nettle Fiber
Nettle fiber, known as aloo or allo, is removed from the plant stem of the Himalayan giant nettle plant. The fiber is stripped from the stem, boiled for several hours, air dried, and handspun into yarns. The hollow fiber looks and feels similar to raw flax.
The nettle plant is a perennial that grows without the use of fertilizers or pesticides. The fiber is used for technical products like bags and ropes as well as for apparel and interior textiles. Because the fiber is hollow, it has good insulating characteristics.
Another nettle fiber from the stinging nettle plant was widely used in Europe until cotton began to replace it because of easier processing. Stinging nettle is being investigated in Europe as a potentially sustainable fiber. The plant can be grown in areas where the soil or climate is not suitable for cotton production.
Nettle must be pond retted for a few weeks and mechanically separated from the plant stem. Degumming in an acidic water bath is required. Nettle is rich in cellulose. It is similar in shape to ramie, coarser than jute, and stronger than ramie. Current plant breeding programs are attempting to improve fiber characteristics.
Several nettle species are used for fiber production, and blended yarns with cotton or lyocell, along with nonwovens, are produced in small quantities. Nettle fibers are also suitable in principle for fiber composites. The roots, stems, and leaves can also provide natural dyes, giving the plant additional value in traditional and sustainable processing.
Bamboo Fiber
There are two types of bamboo fiber on the market. The type that is removed from the bamboo culms, the above-ground stems of the plant, is the natural fiber discussed here. The other bamboo fiber is regenerated from bamboo pulp and is treated with chemicals to form a viscose solution, so it is more commonly found in the market.
The natural bamboo fiber maintains its natural resistance to insects and microbes. It is also absorbent, but it has a somewhat coarse hand, and it is not usually found in the apparel or interiors market. Bamboo is a type of woody grass that grows quickly without the use of pesticides, herbicides, or fertilizers.
Most bamboo is harvested on farmed plantations, so natural bamboo does not threaten wild bamboo forests or natural habitats. Most bamboo is processed in China. As a result, bamboo remains important both as a natural plant resource and as a raw material linked to modern fiber innovation.
Why Bast Fibers Matter Today
Bast fibers remain important because they offer strength, versatility, and a renewable plant-based source for both traditional and modern products. From linen and ramie to jute, kenaf, hemp, hibiscus, nettle, and bamboo, these fibers continue to support textiles, packaging, composites, paper, and sustainable material innovation.
They are also valued because they can be adapted to different processing systems, including cottonized routes, blended yarns, and nonwoven applications. For global buyers, designers, and manufacturers, bast fibers offer a practical balance of natural performance and broad commercial use.
Conclusion
Bast fibers have stayed relevant because they are strong, useful, and closely connected to sustainable material trends. Each fiber has its own character, from flax’s smooth, durable linen quality to jute’s packaging strength, ramie’s brightness, kenaf’s paper potential, hemp’s versatility, and the emerging value of nettle and bamboo. As demand grows for natural fibers with lower environmental impact, bast fibers are likely to remain an important part of textile and industrial supply chains.
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
