Wool Fibers

Wool production and use dates back approximately 10,000 years in Asia Minor. People living in the Mesopotamian Plain at that time used sheep for three basic human needs: food, clothing and shelter. As spinning and weaving skills developed woolens became a greater part of people's lives. The warmth of wool clothing and the mobility of sheep allowed people to spread civilization beyond the warm climate of the Mesopotamia. Between 3000-1000 BC the Persians, Greeks and Romans distributed sheep and wool throughout Europe. The Romans took sheep everywhere they built their Empire including the British Isles. From here the British took sheep to all their colonies.

Fiber Structure

Wool is different to other fibers because of its chemical structure. This chemical structure influences its texture, elasticity, staple and crimp formation. Wool is a protein fiber, composed of more than 20 amino acids. These amino acids form protein polymers. Wool also contains small amounts of fat, calcium and sodium. The crimps in wool let the fibers bunch together, which results in a bulkier material that also acts as a superior insulator. Fine wool, such as Merino, may have dozens of crimps per inch, while rougher wools may only have a handful. Wool fabric has the unique ability to stretch much further than silk, cotton, or other natural fibers and regains its original shape after being stretched. It has an extremely high absorbency rate and is flame retardant, which makes it useful in firefighters’ uniforms and carpeting in trains and airplanes. Wool also does not build up static cling; the fabric will not cling to the body or produce a spark. Wool is naturally absorbent, and can absorb almost 1/3 of its own weight.

Types of Wool Yarn

There are two types of wool yarn – woollen and worsteds.

Woolens: Woolens is a general term describing various fabrics woven from woollen yarn that is spun from the shorter wool fibers. These shorter fibers are not combed to lie flat as in the worsted yarn. This results in soft surface textures and finishes and the weave of individual yarns does not show as clearly as in worsted fabrics.

Worsteds: Worsted is a general term for fabrics woven from worsted yarns that contain longer fibers spun from combed wool. Worsted wool refers to tightly woven, smooth, clear finished goods in a variety of twill and other stronger weaves.

Processing of wool:

The processing of wool involves four major steps. First comes shearing, followed by sorting and grading, making yarn and lastly, making fabric.

In most parts of the world, sheep are sheared once a year, in early spring or early summer. The best wool comes from the shoulders and sides of the sheep.

This is followed by grading and sorting, where workers remove any stained, damaged or inferior wool from each fleece and sort the rest of the wool according to the quality of the fibers. Wool fibers are judged not only on the basis of their strength but also by their fineness (diameter), length, crimp (waviness) and color.

• Scouring: - The wool is then scoured with detergents to remove the yolkand such like dust, suint (sweat) and wool wax.

• Carding:-The carding process involves passing the wool through rollers that have thin wire teeth. Wool is rolled with a roller that is covered with teeth tease apart the staples of wool, laying the fibers nearly parallel to form a soft rope called a 'sliver'.

• Combing: - Combed to separate short from long fibers, ensuring that the long fibers are laid parallel to produce a combed sliver called a 'top'.

• Drawing: - Drawing out of tops into the thickness of one, to thoroughly blend the wool and ensure evenness or regularity of the resulting 'roving'.

• Finisher drawing: - Drawing to reduce the roving thickness to suit the spinning operation and further improve evenness.

• Spinning: -Inserting twist into the yarn to give strength to the finished yarn.

Worsted vs woollen fabrics

• Worsted fabrics are often more expensive than wool spun products due to the longer raw material to resultant yarn processing route used.
• Worsted fabric is stronger and wears better than a woollen spun fabric of equivalent weave construction and fabric weight.
• Worsted fabrics are preferred for trousers, suitings, other garments and upholstery fabrics where a smooth finish is required.
• Woollen spun fabrics are used for jackets, coats, skirts, upholstery fabrics, rugs and blankets where bulk and textured finishes are desirable.

Wool has many beneficial properties which have led to its long history of use.

• Insulation. Wool insulates against heat and cold. It is comfortable in both hot and cold weather because it absorbs moisture vapor. The crimp in the wool fibers makes them stand apart from each other trapping insulating air between the fibers. Still air is one of the best insulators found in nature. In hot weather the absorption/evaporation process works to help keep the body cooler.
• Fire resistant. Wool does not have to be specially treated to become non-flammable. A fabric made entirely of wool is difficult to ignite, burns slowly, and has limited ability to sustain a flame. Wool does not melt when burned and so cannot stick to the skin and cause serious burns.
• Water repellent. Although wool can absorb moisture, it repels liquids. It is naturally hydrophobic. The scales on the outside of the fiber cause liquid to roll off the surface of the fabric. Even if wool does eventually get wet it generates heat and keeps the body warm, not cold and clammy.
• Elastic. Wool has greater elasticity than any other plant or animal fiber. Wool can be twisted, turned and stretched and will still return to its natural shape.
• Durable. The interlocking protein molecules in the fibers of wool have the power to elongate, stretch and recover, creating an extremely robust fabric that will last. Each wool fiber is made up of millions of 'coiled springs' that stretch and give rather than break.
• Static resistant. Wool has very little tendency to collect static electricity because wool naturally absorbs moisture from the air. Wool garments are much less likely to 'spark' or cling to the body.
• Noise insulation. Wool absorbs noise and reduces noise levels.
• Dirt resistant. Wool's ability to absorb moisture and therefore its low build-up of static electricity means that wool does not attract lint and dust from the air. The crimp in the fiber and the scales on the outside of the fiber deep dirt from penetrating the fabric.
• Versatile. Different sheep breeds with their own unique fiber characteristics provide different wools for a wide range of products.
• Dye-ability. Wool is easy to dye. The scales on the surface of the wool fiber diffuse light giving less reflection and a softer color. The proteins in the core of the fiber absorb and combine with a wide variety of dyes and allow the wool to hold its color.
• Comfort. Wool is comfortable to wear because of its elasticity, and moisture absorbing qualities.
• Fashionable. Wool drapes well, is alive, flexible and tailors easily, making it sought after by fashion designers.

Despite the elastic properties and its fire resistance, wool garments and products are often chemically treated as follows:

• Shrink proofing
• Fire proofing
• Moth proofing.

It is important to look at how the fiber was produced, as some animal treatments can leave chemical residue in the fiber. Post shearing treatments are also a cause for concern. Organically grown fibers can still be treated with toxic chemicals for the 'proofing’ mentioned above, and these chemicals can cause health problems. Because of the scales on the wool fibers wool is often itchy and can cause an allergic reaction in some people.

Australia is the world's largest producer of wool.