Pulling out woolen garments: Perm scientists revealed the remarkable properties of this material.

What is wool?

Wool is the hair covering of animals, comprised of guard hairs (longer, coarser, thicker) and down hairs (softer, finer, and wavy). The primary role of the guard hairs is to create structure, protection, and volume for the wool, while the down hairs, or undercoat, help maintain optimal body temperature.

In a cross-section of a guard hair shaft, three layers can be identified: the cuticle made of scale-like plates; the cortex made of spindle-shaped keratinized cells; and the medulla composed of cuboidal and cylindrical keratinized cells. The medulla, when viewed under a microscope, reveals a channel-like structure inside.

Unlike guard hairs, down hairs often lack or have a very poorly developed central part—the medulla. This makes them more flexible and lighter. Down hairs are generally more curled (wavy), which helps create an air layer that aids in thermoregulation. They are shorter than guard hairs and serve to create the undercoat that retains heat and protects the animal's skin from the cold.

— Wool is excellent for warmth due to its structure. Its fibers have a scaly surface that creates air pockets. These pockets trap air, which is a poor conductor of heat, thereby reducing the body's heat loss. Additionally, wool can absorb up to 30% of moisture relative to its own weight while remaining dry to the touch. When moisture is absorbed, it releases a small amount of heat (an exothermic reaction), adding to the feeling of comfort, — explains Ksenia Roman, a junior researcher at the Department of "Mechanics of Composite Materials and Structures" at Perm Polytechnic.

Which type of wool to choose?

Sheep wool is known for its availability, strength, durability, and excellent thermal insulation properties. The diversity of sheep breeds allows for the production of wool with various characteristics—ranging from fine merino to coarser types. Camel wool, on the other hand, is lightweight and very warm, has high hygroscopicity, and possesses healing properties due to its lanolin content. It is also hypoallergenic, though it tends to be more expensive than sheep wool.

— Goat wool comes in two valuable varieties: incredibly soft and fine cashmere, obtained from the undercoat of cashmere goats, and mohair—stronger and shinier wool from Angora goats. Both types are known for their high thermal insulation, but cashmere is more prized. Llama wool has good water-repellent properties; it is less elastic than sheep wool but is ideal for making outerwear, — explains Ksenia Roman.

Alpaca wool is distinguished by its variety of natural shades, hypoallergenic properties, and resistance to pilling. The most expensive and rarest wool comes from the vicuña, a species of even-toed ungulates from the camel family. They inhabit Peru, Bolivia, Chile, and Argentina. This material is known for its exceptional softness, fineness, and warmth.

Natural lanolin soothes human skin

Lanolin is a wax secreted by the sebaceous glands of wool-bearing animals. It was once considered a fat, but since it does not contain glycerides (complex esters of glycerin), it cannot be classified as true fat. This substance mainly contains complex esters of sterols.

Lanolin in wool, especially in sheep wool, is an excellent emollient—it forms a thin film on the skin's surface that prevents moisture evaporation, keeping the skin hydrated. This makes the skin soft, smooth, and moisturized, preventing dryness and flaking.

— The lanolin film also acts as a protective barrier, shielding the skin from adverse environmental effects, such as wind, cold, dry air, and irritants. Additionally, natural lanolin has mild anti-inflammatory properties. It may help soothe irritated and inflamed skin, such as in cases of dermatitis or eczema, — notes Ksenia Roman, a junior researcher at the Department of "Mechanics of Composite Materials and Structures" at Perm Polytechnic.

When washing wool in hot water or with alkaline detergents, lanolin is washed away. There are special liquid gels and detergents available to replenish it.

Wool hinders the adhesion of bacteria and dirt

According to the expert, synthetic fibers with polymer chains containing polar groups can accumulate a positive electric charge due to friction and dielectric properties. This creates a favorable environment for the adhesion and proliferation of bacteria, many of which carry a negative charge. As bacteria break down organic substances in sweat, they release volatile compounds that cause unpleasant odors.

— In contrast to synthetic fibers, natural wool, composed of keratin, has a more complex structure and amphoteric properties. Its surface does not accumulate static charge as actively as synthetic fibers do, and the scaly structure makes it difficult for bacteria to adhere. Furthermore, wool fibers have good hygroscopicity—the ability to absorb moisture. Thus, sweat absorbed by the material evaporates slowly, preventing the buildup of a moist environment conducive to microbial growth, — states Ksenia Roman.

Thanks to the scales, wool can easily be felted into dense felt

— Wool felts into felt due to its unique structure. The scales on the surface of the fibers interlock with each other under mechanical action (thermal treatment, friction, moisture) similar to Velcro. Moisture helps soften keratin, making the fibers more pliable and enhancing their adhesion. As a result of their interweaving, a dense, unbreakable felt is formed, — reports the expert from Perm Polytechnic.

To reduce pilling while increasing tensile strength and abrasion resistance, synthetic fibers like nylon and polyester or natural fibers such as linen and cotton are added to the wool fabric.

Another feature of the scales is that they repel water, so droplets do not absorb immediately, and the air spaces between the fibers create an additional barrier against moisture. This is why woolen items do not get wet instantly in the rain.

Caring for woolen items

The advantage of wool over synthetic fabrics begins with its biodegradability. The natural material decomposes easily by microorganisms in the soil. Moreover, wool is a renewable resource that regularly regrows in animals, and its production requires less water and energy compared to creating fabrics through chemical synthesis.

According to Ksenia Roman, such clothing has self-cleaning properties, allowing for less frequent washing. It is characterized by strength and durability, and with proper care, can last for many years, reducing consumption and waste.

Often, dry cleaning or airing is sufficient for them. When washing items, it is important to follow the care instructions on the label, using special products and cool water. It is crucial to remember that these items should be dried flat and naturally. Never in a tumble dryer, on a radiator, or in direct sunlight.

Gentle handling of woolen items is the key to their longevity and protection from "uninvited guests," including moths.

— Moths, which feed on keratin, the main protein in wool, can damage the item, so it is essential to wash or clean them thoroughly before storing. This insect is attracted to the smell of dirt, sweat, and food, so it is important that items are clean before long-term storage. Next, care should be taken for airtight packaging, placing them in bags, containers, or covers made of dense fabric to create a physical barrier.

Protection can be enhanced with natural repellents, such as sachets with lavender, cedar shavings, or herbs that deter insects. Chemical agents like mothballs or paradichlorobenzene are also effective but require careful use and have an unpleasant scent for humans, — says Ksenia Roman, a junior researcher at the Department of "Mechanics of Composite Materials and Structures" at Perm Polytechnic.