Natural Wool: Its Characteristics, Manufacturing Process, and Good Washing of Woolen Fabrics
Natural wool is the fiber obtained from sheep and other animals. For example cashmere and the mohair of goats, Qiviut of muskoxen, angora of rabbits, and Camelid wool. Sheep wool is the most preferred because it has important physical properties distinguish it from camel hair, goat hair, and others.
The wool is consists of protein with a low proportion of fat. So it is quite different from cotton which is mainly cellulose.
Global raw wool production is approximately 3.1 million tons per year. The most important producing countries of wool are Australia, New Zealand, China, Russia, Uruguay, Argentina, Turkey, Iran, United Kingdom, India, Sudan, and South Africa.
There is currently a global interest in reviving the use of organic wool, an initiative that is funded by wool producers from Australia, Britain and New Zealand in an effort to encourage more producers to use wool in the carpet and clothing industry instead of other synthetic fibers.
History of Wool
Wool fibers have been important to the primitive human tribes since more than 10,000 BC. Wool was woven and coordinated by the Babylonians as well as in northern European tribes. Textile tools were relatively basic.
The Persians, the Greeks, and the Romans were interested in raising sheep and weaving wool.
The Romans built a wool factory in Winchester, England, in 50 AD.
After Norman's invasion of Greece in the 12th century, Greek weavers were sent to Italy as slaves who stimulated the Italian textile industry into extraordinary works. In the 14th century, the Flemish Weavers escaped from the Spanish invasion into England, leading to the flourishing of the wool industry.
Moroccan Arabs used to breed sheep and produce fine wool. They invented many wool weaving processes and transported them to Andalusia (Spain).
During the fifteenth and eighteenth centuries, sheep and wool were an important economic force. For example, countries such as England and Spain prohibited the export of sheep and raw wool. In 1660, two-thirds of England's foreign trade was based on exports of woolen textiles.
In 1789, two Spanish Merino Rams and six Spanish Merino Ewes arrived in South Africa after they were granted by the Spanish king to the Royal Dutch Orange House where they could not cope with the cold and rainy weather. The Spanish sheep Merino flourished in South Africa. Later some descendants of the Spanish Merino sheep were sent to Australia.
The first Merino sheep arrived in Australia in 1797. The sheep were descendants of the Royal Merino herd of Spain. After selective breeding Australian farmers produced soft Australian Merino wool and then shipped to England for industrialization.
The Arabs of the Levant also cared about raising sheep and wool yarn.
In 1941, the United States Congress passed the Wool Products Classification Act. This act was to protect producers and consumers from the unknown existence of substitutes and mixtures in wool products. This law required that all products containing wool (except for upholstery and floor coverings) bear a mark indicating the content and proportions of materials in the fabric.
The fall in the price of wool began in late 1966 due to the decline in demand for natural wool with increased use of synthetic fibers resulting in a sharp decline in production.
In the early 1970s, for the first time, a wool washable machine appeared.
During June 2008, the finest bale of wool was sold at an auction for a seasonal record of US $ 2690 per kilo. Hillcreston Pinehill Partnership produced this bale, which measured 72.1% yield, 11.6 microns, and had 43 Newton per kilotex strength. The bale achieved $ 247,480 and was exported to India.
The United Nations General Assembly declared 2009 the International Year of Natural Fibers, including wool.
Characteristics of Wool Fibers
The wool fibers have three-dimensional crimps, 25 waves per 10 cm in fine fiber, and 4 waves per 10 cm for coarse fibers. The fiber length ranges from 3.8-38 cm. The fiber length of 5-12 cm is used in the garment industry because this length allows the yarn to be manufactured with greater precision. The diameter of the fiber varies from 14 micrometers to more than 45 micrometers. The fibers of some sheep may reach a diameter of 70 μm, these fibers are used in the carpet industry. The higher price is paid for fibers with the fine diameter, especially if they are identical in diameter. The color of sheep's wool varies from white to brown and black. White is more desirable than other colors. The dark fibers cannot be successfully dyed for the difficulty of removing or hiding the natural color.
Wool fibers absorb water from the surrounding atmosphere better than other fabric fibers because they have pores and interstitial spaces in their composition. Wool fibers absorb about 18% of their weight in moisture, but the human does not feel this moisture, and this is a very important health factor must be provided in clothes.
Fabric made from woolen fibers gives a warmer feel than other plant or industrial fibers.
Wool is a good insulation for heat, preventing heat from leaking out, and cold air from leakage inside. Therefore, woolen textiles are used as a protective cover for heat in hot places as well as cold in the cold winter.
Wool fibers are very flexible, they increase about 30% of their length at the simple tensile strength, and return to normal condition when removing tensile strength.
Woolen fabrics are non-flammable and stop burning when the fire source is removed.
Wool transfers ultraviolet rays to the body.
Wool fibers dissolve in base (alkaline) solutions and are fixed in acidic solutions.
Wool fiber shape
Wool Fiber Micro Structure
Wool Fiber Micro Structure
Through microscopic examination of wool fibers, we find that they are made from protein molecules. Keratin protein is a crystalline copolymer; the repeated units are amino acids.
Wool fibers are also cross-linked through the disulfide bonds present in amino acids Cysteine.
The microstructure of wool fibers consists of three basic parts: the cuticle, cortex, and medulla.
The cuticle (epidermis) is a layer of overlapping cells surrounding wool fibers. There are three cuticles ( epicuticle, exocuticle, and endocuticle).
The cortex is the internal cells form 90% of the wool fiber. There are two basic types of cortical cells; ortho cortical, and paracortical, each with a different chemical composition. In superior fibers, these two types of cells are of distinct halves. The cells expand differently when the moisture absorbed, making the fiber curve, this creates a crease in the wool. In rough fibers, ortho and para cortical-chemical cells are more random so there is less curl. Also, fiber crease makes wool an insulator for air.
The medulla is a mass of degenerated cells in the central part of the fiber. This layer may disappear or be difficult to see in the fine wool.
Wool Sheep breeds
Wool Sheep Types
Fine (Soft wool): In this type, the fiber diameter does not exceed 25 microns and the average length of wool is 9-6 cm. Wool fibers here are very wavy, the fiber density is large, the fat ratio is high, and the wool is white. This type of wool can be obtained from the Merino sheep breeds.
Medium (Semi-soft wool): Wool is white in color and average fat. The thickness of wool fiber ranges from 25-55 microns and wool length ranges from 8-10 cm. This type of wool can be obtained from the Tsigai, Suffolk, Hampshire, and Tunis sheep breeds.
Long wool: This type of wool is white, has a coarse and dry feel. This wool can be obtained from the Awassi and Lincoln sheep breeds.
Carpet wool: This type of wool contains more fats than coarse wool as well as more softness. This wool can be obtained from Tajikistan (Marco Polo sheep) and Karakul sheep. This kind of wool is more suitable for the carpet industry.
Wool Manufacturing Processes
The Manufacturing Process of Wool
- Shearing: Sheep shearing is the process of cutting wool fleece from Sheep. Each sheep is sheared once a year. Sheep are sheared in all seasons but spring is always preferred for this process. There are two ways to shear:
Hand shearing: In this method, different types of scissors are used, requiring a long time and a large number of workers, and may cause injury to the animals, as well as irregular shearing wool.
Automatic shearing: It is made by electric machines, and spread in many countries because of the saving of time and effort, in addition, to get good quality shearing, and do not cause any injuries to sheep when carried out by trained shearers.
- Sorting: In sorting, wool is divided into four sections of different quality fibers (fleece, broken, bellies, and locks). The best quality of wool comes from the shoulders and side of the sheep which are used for clothing. The lower quality comes from the bottom legs and used for carpet making.
- Scouring: Is a process of cleaning the greasy wool because it contains a high level of lanolin, the sheep's dead skin, sweat residue, pesticides and vegetable matter from the animal's environment. It is a water bath contains alkaline, soda ash, and soap. The rollers of the cleaning machines press the excess water from the wool, but the wool is not allowed to dry completely. After this process, wool is processed with oil to make it easier to manage.
- Carding wool: At this stage, the fibers are separated and then assembled again into a loose rope (sliver) by removing short fibers and replacing them with long parallel fibers. The combing machine consists of one large roller and smaller ones surrounding it. All cylinders are covered with small metal teeth, and when the wool reaches more on the teeth become finer.
- Spinning: The thread is formed by spinning the fibers together to form the strand. The plexus is woven with two or three other threads. Because the wool fibers cling to each other, it is easy to expand and spindle the wool into yarns. Woolen yarns can be spun on any number of spinning machines. After this stage, spun threads are wrapped around rollers or commercial drums.
- Weaving: The woolen threads are woven into the fabric. In this industry, two basic types of weaves are used, the plain and the twill weaves. The most common method is the plain weaving which gives soft surface textiles. The twill method gives more beautiful and more precise wool textiles, but in turn is more expensive.
- Finishing: After weaving, wool fabrics are subjected to a series of final processing including Fulling or tucking is a step in the woolen clothing industry that involves cleaning the cloth to eliminate oils, dirt, and other impurities, and make them thicker. Crabbing is a process that ensures that the fabric expands or is relaxed as necessary and equips the thickness of the fabric. Cribbing prevents the formation of wrinkles or uneven contraction. Although wool fibers can be dyed before carding (combing) process, dyeing can also be done after weaving the wool into the fabric.
The Manufacturing Process of Wool
Uses of Natural Wool
Wool is used in the manufacture of clothing, blankets, insulation, upholstery, and saddle cloth.
Merino wool has been used in children's products such as baby blankets and infant sleeping bags.
Preliminary studies of woolen underwear have found that they prevent heat and rashes because they absorb moisture more than other fibers.
A blend of wool and Kevlar (a synthetic fiber used in body armor) were discovered by researchers at the Royal Melbourne School of Technology of Fashion and Textiles. The wet Kevlar loses about 20% of its effectiveness, so it requires expensive waterproofing. Mixing wool with Kevlar reduced the cost of using Kevlar alone.
Good Laundry of Wool
Hand washing is the best way for natural woolen fabrics. Wash the wool with a large amount of warm water, just by pressing it. Do not use hot water as it changes the properties of wool. When wool is rubbed with soap, it causes shrinkage of the wool and increases wrinkles. It is also not necessary to increase the amount of soap used because when the soap dissolves in the water gives an alkaline effect and if the quantity increased, it will increase its bad effect in the wool fabric. Also, it is best to change the washing water two or three times, and water temperature is equal at all times.
- Technology in Australia 1788-1988, Chapter 5, page 267. Technology in Australia 1788-1988, Chapter 5, page 267, Bicentenary study by distinguished Fellows of the Australian Academy of Technological Sciences and Engineering of development of technology over two hundred years.