Wool

Wool is a versatile textile fiber made primarily of protein.

While most people associate it with sheep, wool can also come from goats, rabbits, and camelids. It is chemically distinct from plant fibers like cotton, which are made of cellulose. Instead, wool is more similar to silk because both are animal-based proteins. This unique chemical makeup gives wool special properties that make it highly valuable for clothing and industry.

It is used for everything from everyday apparel to specialized safety gear.

Inside the skin of an animal, wool grows from tiny cells called follicles. These follicles are located in the epidermis, the top layer of skin, and push down into the dermis. There are two main types of follicles: primary and secondary. Primary follicles produce three different types of fiber: kemp, medullated fibers, and true wool. Kemp is a coarse hair found on sheep. Medullated fibers look like hair but lack the elasticity found in true wool. Secondary follicles are important because they produce only true wool fibers. True wool is characterized by its crimp and its elasticity.

Crimp refers to the natural wave found in each individual wool fiber. This wave is essential because it helps fibers attach to one another during spinning. Without crimp, fibers would not bind well into yarn. Crimp also creates bulk in fabrics, which allows them to trap air and retain heat. The amount of crimp often indicates how fine the wool is. For instance, fine Merino wool may have up to 40 crimps per centimeter. In contrast, coarse wool like karakul may have less than one crimp per centimeter.

To turn a fleece into a product, it must undergo several processing stages. First, a shearer cuts the fleece from the sheep.

Next, a wool classer inspects the wool to group it by quality. They sort it into categories like fleece, which is the highest value, or bellies and locks, which are lower value. After sorting, the "greasy wool" must undergo scouring. Scouring is a cleaning process that removes dirt, sweat, and vegetable matter. This can be done with simple warm water or complex industrial machines using detergents.

Some producers leave a small amount of lanolin, a natural grease, to create water-resistant garments.

Quality is often measured by fiber diameter, which is expressed in microns. A micron is a very tiny unit of measurement. The finer the diameter, the higher the value of the wool. Merino sheep produce some of the most valuable wool in the world. For example, "Ultrafine Merino" has a diameter of less than 15.5 microns. The industry benchmark for excellence in Australia and New Zealand is called 1PP, which represents wool that is 16.9 microns or finer.

Other sheep, such as those raised for meat, produce much coarser wool with diameters between 40 and 150 microns.

Wool also possesses remarkable physical properties, particularly regarding fire safety. Wool ignites at a higher temperature than cotton or many synthetic fibers. It has a lower rate of flame spread and does not melt or drip when exposed to heat. Instead, it forms a char that acts as an insulator. Because of these traits, wool is often used for high-safety environments. It is frequently specified for carpets on trains and aircraft. It is also used for the clothing of firefighters and soldiers who may face fire risks.

Humans have relied on wool for thousands of years. Archaeological evidence suggests that people began selecting for woolly sheep around 6000 BC.

In ancient Roman times, wool was a primary clothing material alongside linen and leather. By the 12th and 13th centuries, wool trade became a massive economic driver. Large quantities of raw wool were baled and shipped to textile cities like Ypres and Ghent. Today, the industry continues to evolve through the use of both virgin wool and recycled fibers. This long history shows how a single biological fiber can shape global economies and cultures.