Wool is a natural textile fiber derived from the protective coats of various animals, primarily domesticated livestock. This animal fiber is composed mainly of keratin, a protein also found in human hair and nails. The unique structure of wool fibers allows them to be spun into yarn, creating textiles prized for their warmth, durability, and ability to manage moisture.
The Primary Source: Wool from Sheep
The vast majority of commercial wool originates from the domestic sheep, known scientifically as Ovis aries. Sheep wool is a complex biological material, with each fiber composed of a cuticle, cortex, and medulla, though the medulla is often absent in finer wools. The cortex, which makes up the bulk of the fiber, consists of long chains of keratin protein that contain small, air-filled spaces, which are instrumental in trapping heat and providing insulation.
A defining characteristic of sheep wool is its natural waviness, or crimp, which is the result of two types of cortical cells expanding at different rates when they absorb moisture. This crimp adds bulk and elasticity to the wool, allowing fabrics to resist compression and maintain their shape while trapping a significant volume of air for thermal regulation. Wool is harvested through a process called shearing, where the entire fleece is removed, typically once per year, using specialized electric clippers.
Certain sheep breeds are selectively raised to produce the finest quality wool, with the Merino sheep being the most well-known example. Merino wool fibers are exceptionally fine, often measuring less than 22 microns in diameter, allowing them to feel soft against the skin. Since the fleece of a Merino sheep never stops growing, regular shearing is necessary for the animal’s welfare.
Specialty Fibers and Other Animal Sources
While sheep are the most prolific source, a range of other animals provides specialty fibers that offer distinct properties like superior softness or sheen.
Goat Fibers (Cashmere and Mohair)
Goats are a source of two highly valued fibers, Cashmere and Mohair, which come from different breeds. Cashmere is the soft, downy undercoat fiber from the Cashmere goat, typically measuring between 12 and 18 microns. Cashmere is noted for its lightweight feel and exceptional insulation, being considerably warmer than standard sheep’s wool. Mohair, by contrast, is derived from the Angora goat and is recognized for its high luster and sheen, often called the “diamond fiber.” Mohair fibers are generally thicker than cashmere, ranging from 25 to 45 microns, but they possess great strength and durability.
Camelid and Rabbit Fibers
Camelid species from South America, such as the Alpaca and Llama, also contribute unique fibers. Alpaca fiber is prized for being soft, luxurious, and naturally free of lanolin, making it hypoallergenic and easier to process. The fiber’s hollow core traps heat efficiently, providing warmth without excessive weight. Llama fiber tends to be coarser and is frequently used for durable outer garments or rugs. The Angora rabbit produces Angora wool, an extremely fine and fluffy fiber, which is often blended with other wools to increase elasticity.
Preparing the Raw Fiber for Use
Once the animal’s fleece is harvested, it begins a multi-step process to prepare it for spinning into yarn. The first step is skirting, which involves laying the raw fleece flat and removing the heavily soiled or matted edges, such as the belly wool and any areas contaminated with vegetable matter. This initial cleaning ensures that only the best quality fiber moves forward in the process.
The next significant step is scouring, a thorough washing process using hot water and a detergent to remove the natural grease, or lanolin, and accumulated dirt. Scouring must be done carefully without excessive agitation to prevent the fibers from tangling and shrinking, a process known as felting. The raw wool is then dried and prepared for mechanical processing.
The clean, scoured fiber is then subjected to carding, where it is passed through rollers or brushes with fine wire teeth to untangle and align the fibers parallel to one another. This step creates a continuous, fluffy strand called a roving or batt. The final preparation is spinning, where the aligned fibers are drawn out and twisted together to create a continuous strand of yarn for weaving or knitting textiles.