Natural Plant Fibers The - Yarns and fibers
Natural plant fibers, primarily made up of cellulose, come from a variety of sources. Some are derived from fruit, such as cotton or kapok. Bast fibers, on the other hand, are found in the stems of plants such as flax and hemp. Lastly, some fibers, less widely used on an industrial scale, are extracted from leaves, bark or the fibrous layers surrounding nuts.
Here is a list of natural plant fibers, classified by origin:
Fruit: cotton, kapok
Stem: flax, hemp, nettle, ramie, lotus
Nuts: coconut
Leaves: pineapple, sisal (agave), raffia, aloe vera
Bark: jute, baobab
Cotton
Origins
Cotton fiber comes from the seminal hairs that grow on the surface of the seeds of the cotton plant, a shrub in the Malvaceae family (Gossypium). Originally, this plant, which can be annual or perennial, was initially grown in India, Ethiopia and Sudan. Its cultivation then spread to tropical and subtropical zones. Today, five countries produce 75% of the world’s cotton: India, China, the United States, Brazil and Pakistan. Although between 40 to 50 botanical species of cotton plants have been identified, only four are used for fiber production (the Gossypium hirsutum variety accounts for 95% of world production). The oldest woven cotton garment, found in Pakistan, dates back to 3000 BC. Today, cotton is the most widely used natural fiber in the fashion industry.
Production & Transformation
Growing cotton requires very specific weather conditions. Above all, for the plant to grow it needs plenty of water and humidity, and then, to reach maturity, it needs a warm climate (between 21° and 37°). When the boll (fruit) opens, the cotton is harvested as “seed cotton”, which is a combination of fibers, linters (downy fuzz) and seed. Ginning separates the fibers from the seeds (around 38% of seed cotton). The ginned fiber is then assembled into bales (a unit of measurement ranging from 170 to 233 kg). These are then sorted by quality and sent to the spinning mill.
Classification
Fiber grading is determined by three factors: length, fineness and grade (color, brightness, impurities). Fiber length, the main criterion for determining quality, ranges from 1 cm to 3 cm on average, but some fibers are much longer. Fibers are considered short when they are under 20mm, medium between 20 and 30mm, and long when they exceed 30mm. Long-staple cotton varieties such as Giza (Egypt), Sea Island (Caribbean) and Pima (USA and Peru) are the most prestigious. Once spun, long-staple cotton is more durable, soft and lustrous.
Characteristics
Use advantages: Cotton is a soft, comfortable and lightweight fabric that can be worn year-round. It’s easy to dye, bleach and wash, and strong wet or dry. It is naturally breathable and promotes moisture transfer. It does not accumulate static electricity.
Use disadvantages: Cotton dries slowly, and is susceptible to mildew. It may shrink and wrinkle. Washing may cause discoloration.
Production impacts
During the growing season, cotton plants are vulnerable to disease, fungus and insects. Its intensive cultivation thus requires the use of inputs, fertilizers and pesticides. Conventionally grown cotton also requires large amounts of water for irrigation and treatment.
In some demographic zones, cotton is grown under social conditions that do not comply with international labor standards.
Gradually, initiatives are emerging to improve the environmental and social impacts of cotton, including organic and regenerative farming, “family farms” and other alternative, more sustainable models.
Read also: Natural Animal Fibers
Linen
Origins
Two types of flax are cultivated : flax seed, used to produce oil, and flax fiber, used by the textile industry to make linen. Flax fibers are known as “bast fibers”, meaning they are contained in the stem of the plant.
Europe is the world’s leading producer of flax fiber, with three-quarters of all long-fibers grown in France, Belgium and the Netherlands. Linen represents less than 0.5% of the world’s fiber production.
Nevertheless, this fiber has been experiencing renewed interest in recent years, thanks to its superior quality, environmentally-friendly cultivation and, for the European market, its local appeal.
Production & Transformation
Flax is planted every 7 years as a rotational crop. It requires little nitrogen, boosts the biological activity of the soil and improves the quality of subsequent crops by 20 to 30% (wheat, potatoes, rapeseed). Sowing takes place in March and April, and the plant reaches maturity after 100 days. The flowers live for just one day, opening in the morning and fading in the evening.
Once harvested, the flax is retted. This initial transformation phase consists of allowing the micro-organisms present in the soil to eliminate the pectose that binds the textile fibers to the woody part of the stem. Next comes the scutching phase, during which the fibers are separated from the wood present in the stem (shives). The entire plant is used: long and short fibers, shives and seeds. The fibers are then combed into long ribbons. Lastly, fibers from different harvests are blended to ensure uniform quality, before being sent to the spinning mill.
Classification
Linen fibers range in length from 25mm to 150mm. They are divided into two categories: long fiber and short fiber. Fiber length and color vary from crop to crop, depending on weather conditions.
Characteristics
Advantages: Linen is a heat-regulating, breathable fiber that facilitates moisture transfer. It has a lustrous appearance, a certain firmness and good dye affinity. Linen is also resistant to insects and high temperatures. It is an environmentally-responsible fiber because it is local (for the European market), traceable, biodegradable and helps conserve water and soils.
Disadvantages : Linen is not very elastic and known to wrinkle. It is hard to bleach, which makes it difficult to obtain pastel or bright colors. Over time, and with many washings, it can show signs of wear.
Hemp
Origins
Hemp, or cannabis sativa, is an annual herbaceous plant. As opposed to the subspecies cannabis indica, which is illegal to grow in France, European hemp is monitored to ensure that it contains no more than 0.3% THC (psychoactive substance).
Originally from Asia, hemp is one of the world’s oldest domesticated plants. Today, Europe is the world’s second largest producer after China. Hemp, like flax, is a bast fiber: the fiber is located in the stem.
Production & Transformation
Hemp is grown in mild climates. It is sown in April-May and harvested from late August to October. It’s a fast-growing crop, reaching 3 to 4 m depending on the variety. Processing stages vary depending on the desired end product.
Hemp is beaten during harvesting, to recover the seed, or hempseed. Then it is mowed and baled. Next comes the defibering process, which involves beating to separate the fibers (which surround the stalk) from the wood (the shives). The fiber can then undergo various treatments, such as degumming, carding and combing.
Classification
The lengths of the fibers, and how homogenous they are, determine their quality and use.
Two spinning processes exist. The most common is wet spinning, which makes it possible to obtain 100% hemp yarns. In dry spinning, the fibers are cottonized through a variety of mechanical and chemical processes. The combination of these processes makes it possible to achieve fibers of differing qualities. Using the dry spinning method, the maximum percentage of hemp per yarn is 40%.
Characteristics
Advantages: hemp is an extremely strong fiber (8 times stronger than cotton), and becomes even stronger when wet. Hemp is also resistant to UV rays, mildew and insects. Hemp is hypoallergenic, and softens with repeated washing. It is a breathable, climatic fiber.
Disadvantages: due to its high lignin content (25%), it has a rustic look and handle. Its low elasticity and irregular fiber size can make it difficult to spin.
Sources:
Le dictionnaire des textiles, Maggy Baum et Chantal Boyedieu, 2006
The textile manual, Fashionary, 2020
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