Natural Animal Fibers

October 26, 2023

Fabrics

Textile Glossary

Natural animal fibers, which consist mainly of keratin, take two forms: continuous fibers (filaments) and staple fibers.

Staple animal fibers are animal hairs which are commonly known as wool.
Four main species supply wool suitable for textile use:

Ovine: different breeds of sheep. They produce most of the wool sold on the market.
Goats: different breeds of goat. Depending on their specific characteristics, they produce mohair, cashmere and angora. (Rabbit hair is sometimes referred to as angora. However, rabbit farming is becoming increasingly rare following animal welfare concerns.)
Cattle: yaks
Camelids: camels, llamas, alpaca, guanacos, vicuñas, etc.

The only natural continuous fiber is silk.
This filament forms the cocoon of certain butterflies (notably the Bombyx of the mulberry tree).

Wool

Origins

Wool is a special kind of mammalian hair. Consisting essentially of keratin, it protects Bovidae from bad weather.

An animal fleece is all the usable hair of an animal. Traditionally, wool refers to sheep fleece. However, fleeces from other animals, such as mohair wool (Angora goat) or cashmere wool (cashmere goat), are also known as wool.

This article focuses on sheep’s wool, which accounts for most of the world’s wool production.

Sheep are thought to be one of the first domesticated species; humans have been working with wool for around 10,000 years. Until the end of the 18th century, wool production was confined to European and Mediterranean regions. It then spread to the Southern Hemisphere, notably to Cape Town, Australia, New Zealand and La Plata which subsequently became the world’s leading producers.

The Merino breed of sheep, which produces the wool of the same name, has been developed through selection and cross-breeding to obtain the highest quality wool. The qualities of Merino wool include softness, fineness, evenness, elasticity, crimp and whiteness. The first Merino sheep were introduced to Australia in 1797. The country is now the world’s leading exporter, with wool production made up of 70% Merino wool.

Production and Processing

Intensive sheep farming is mainly practiced in countries in the Southern Hemisphere. A flock, which can be on average 15,000 to 20,000 heads, is made up mainly of females and castrated males. Breeding is carried out by rams selected for the quality of their wool.

A sheep is shorn annually in spring and produces a fleece weighing 3-6kgs. The climate has a major influence on the quality of the wool. In dry regions, it will often be finer but more fragile (tender) and in wet areas, thicker and more resilient (sound).The fleece is made up of two types of hair: guard hair (coarse surface hair) and down (fine, short, wavy hair). The latter is used as a textile fiber. The entire fleece after shearing retains its wax-like coating. This “wool grease” is a mixture of sweat, waxy ester (a protective greasy substance called lanolin) and various impurities (staining, vegetable matter, etc.).

Once the wool has been sorted and washed, it is delivered in bales (weighing 190kg in Australia) to brokers for initial classification. The aim is to create homogenous batches using batches from a large number of farms. Additional laboratory tests are carried out to provide certificates. With a certificate and sample of the wool, a buyer can gauge the quality of bales (the visual aspect, feel, fiber length and tenacity – tender or sound).

Classification and Characteristics

Sheep’s wool is divided into two categories: short-fiber (carded) wool and long-fiber (combed) wool, destined to be combed for long-fiber spinning. It can be divided into five main groups based on micron:

Extra-fine wool (less than 18.5 microns): Garments worn close to the skin, such as shawls, scarves, hats, baby clothing, gloves, and underwear.
Fine wool (18.5 to 20.5 microns): High-quality garments, fabrics, and knitting yarns that are soft to the touch.
Medium (20.6 to 22.5 microns) and broad wool (22.6 to 25 microns): A variety of woven apparel fabrics, knitting yarns, and home furnishing products, such as heavy sweaters, socks, blankets, carpets, and industrial felts.
Coarse wool (26 to 32 microns): Rugs and upholstery fabrics.
Very coarse wool (32 to 48 microns): Carpets

The finest (highest quality) fibers are used for clothing, the medium fibers for household linen, and the thickest for carpets.
In addition to the type of wool (carded or combed) and the breed of sheep, fibers are classified by style (the area of the body from which they come, such as the fleece or the belly) and color (whiteness is traditionally favored).

Properties

The fineness and length of the fibers depend on the species. Thermoregulatory properties of the different wools relate to the altitude and temperature, for example, of the environment of the species. They also depend on the area of the body on which they have grown.

Advantages

Wool is the only naturally curly fiber with a consistent elasticity and ability to be smoothed out. The fiber has shape memory when subjected to heat, steam, pressing or felting.

It is an extremely versatile fiber which, depending on how it is spun, woven, knitted and finished, can take on a wide variety of aspects: fine and fluid, soft, lustrous (after calendering), fluffy (after brushing), etc.

It is hydrophilic (it can retain 33% of its weight in water vapor), insulating and thermoregulating. Another advantage of wool is its easy-care attributes: it requires fewer washes than other fibers. Odors (from perspiration or other sources) are simply removed by airing the garment.

It is also anti-static, resistant to noise and vibrations, and flame retardant. Its long fibers make it easy to recycle, and it is naturally biodegradable.

Disadvantages

The scaly structure of wool fiber makes it susceptible to felting. Felting is caused by a combination of four factors: water, heat, soap and mechanical movement. If left unchecked, felting can become a major drawback in the caring of finished products. If exposed to a lot of sunlight, wool discolors and can weaken. When wet, its strength decreases and it is prone to shrinkage. Rustic wools can also irritate the skin.

An overview of the properties of other animal hairs:

Cashmere (cashmere goat): a supple, notably soft and light fiber with excellent thermoregulatory properties.
Mohair (Angora goat): a fiber that is ultra-soft, shiny, light, fluffy and bulky.
Yak: a fiber that is ultra-soft, resistant, light and thermoregulating
Dromedary (domesticated): a fine, silky fiber. It is anti-static, repels dust and is a very good thermal insulator.
Came: Soft and flexible fiber with excellent thermal properties.
Llama (domesticated): a particularly soft, warm fiber (warmer than alpaca).
Alpaca (domesticated): a particularly warm and soft fiber (softer than llama).
Guanaco (wild ancestor of the llama): a fiber that is finer than that of the llama.
Vicuña (wild ancestor of the alpaca): a luxurious fiber, superior in quality to that of the alpaca.

Impacts of production

Conventional wool production can be, in certain cases, also criticized for not respecting animal welfare, in particular the practice of mulesing. Now banned in several countries, the aim of this practice is to prevent the development of parasites that damage the animal’s health and wool production. ‘Mulesing free’ labels guarantee that the wool does not come from herds that have undergone this operation.

Silk

Origins

Silk is a filament produced (or ‘spun’) by butterfly caterpillars to form their cocoons.Two main types of butterflies produce silk that can be used in industrial spinning. The Bombyx mori worm produces the silk filament used mainly in the textile industry, and the Antheraea pernyi butterfly, whose caterpillars produce wildtussah silk. The oldest fragments of silk date from around 2570 BC. Synonymous with luxury, its production was exclusively Chinese for centuries. It was exported throughout Asia and from the 2nd century BC, Persian merchants used the Silk Road to spread trade in silk across Europe.

European production became industrialized in the 19th century, with Lyon becoming a hub of the silk trade. However, the European silk industry suffered a major decline due to several factors: silkworm epidemics, shortages, increasingly efficient Asian production and the arrival of artificial fibers.

Today, silk production represents a tiny proportion of global textile fiber production. Nevertheless, its unique status makes this exceptional fiber a market worth several billion U.S. dollars.

China remains the world’s leading producer, accounting for over 60% of the market. It is followed by India.