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Wool classing is the production of uniform, predictable, low-risk lines of
wool Wool is the textile fibre obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have properties similar to animal wool. ...
, carried out by examining the characteristics of the wool in its raw state and classing (grading) it accordingly. Wool classing is done by a wool classer.


Basis for classification

Some of the qualities a wool classer examines when classing wool are:Wool Classification Manual
by the National Wool Growers Association, of Southafrica
* '' Breed of the sheep'': Shedding breeds will increase the risk of medullated or pigmented fibers. Any sheep likely to have dark fibers should be shorn last to avoid contamination. The age of the sheep will have a bearing on the diameter and value of the fibers of wool, too. * ''Usage of chemicals'': Ensure that all rules are followed. * ''Brands'', ''seedy jowls,'' and ''shanks'': Must be removed from fleeces and broken. * ''Stains'': Must be removed from bellies and fleeces and identified in a separate line. * ''Spinning capacity'': The number of bends per unit length along the wool fiber approximately indicates the spinning capacity of the wool.
Fiber Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...
s with a fine crimp have many bends and usually have a small diameter. Such fibers can be spun into fine
yarn Yarn is a long continuous length of interlocked fibres, used in sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the production of textiles. Thread is a type of yarn intended for sewing by hand or machine. Modern manu ...
s, with great lengths of yarn for a given weight of wool, and higher market value. Fine fibers may be utilized in the production of fine garments such as men's suits whereas the coarser fibers may be used for the manufacture of
carpet A carpet is a textile floor covering typically consisting of an upper layer of pile attached to a backing. The pile was traditionally made from wool, but since the 20th century synthetic fibers such as polypropylene, nylon, or polyester ...
and other sturdy products. The unit of measurement is crimps per inch or crimps per centimeter. The average diameter or mean fiber diameter is measured in micrometers (
micron The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Un ...
s). Before the advent of technology to measure crimps and diameter, English wool-handlers categorized wool based on their fineness by estimating spinning capacity using vision and touch, which is known as the Bradford system. * ''Strength'' (also known as ''
tensile strength Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials ...
''): Determines the wool's ability to withstand processing. Weaker wool produces more waste in carding and spinning, and may be used for the production of
felt Felt is a textile material that is produced by matting, condensing and pressing fibers together. Felt can be made of natural fibers such as wool or animal fur, or from synthetic fibers such as petroleum-based acrylic or acrylonitrile or wood ...
or combined with other fibers,. * ''
Color Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...
'': Indicates whether wool can be
dye A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and ...
d in light shades. Color may be graded depending upon the natural color, impurities and various stains present. Severely stained wool decreases prices dramatically. However, it is hard to assess color accurately without proper measurement, since some stains will wash out in the processing, whereas others are quite persistent.


Procedure

The fleece is skirted to remove excess fibres, seeds, burrs, etc. to leave the fleece as reasonably even as possible. The wool taken from different parts of a
sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to domesticate ...
are graded separately. The fleece forming the bulk of the yield is placed with other fleece wool as the main line, while other pieces such as the neck, belly, and skirting (inferior wool from edges) are sold for such purposes where the shorter wools are required (for example fillings, carpets, insulation). While in some places, crimp may determine which grade the fleece will be put into, this subjective assessment is not always reliable, and processors prefer that wools are measured objectively by qualified laboratories. Some of the superfine wool growers do in-shed wool testing, but this can only be used as a guide. This enables wool classers to place wool into lines of a consistent quality. A shed hand, known as a wool presser, places the wool into approved wool packs in a wool press to produce a bale of wool that must meet regulations concerning its fastenings, length, weight, and branding if it is to be sold at auction in
Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologic ...
. All Merino fleece wool sold at auction in Australia is objectively measured for fiber diameter, yield (including the amount of vegetable matter), staple length, staple strength and sometimes color. A classer is also responsible for a pre-shearing check to be made to ensure that the wool and sheep areas are free of possible contaminants. A classer supervises shed staff during shearing, and trains any inexperienced hands. At the end of shearing, classers have to provide full documentation concerning the clip.


Other systems of wool grading

"Blood" or "Blood system" was one of the old ways to grade wool. It was a term that is used with different fractions to show how much merino blood a sheep has. Each blood grade corresponds to a numerical grading system based on the yarn's fineness or count.{{Cite book, last=Christie, first=James Wiley, url=https://books.google.com/books?id=2f8Mi_APWxkC&dq=blood+system+wool&pg=PA11, title=Grading Wool, date=1945, publisher=U.S. Department of Agriculture, pages=11, language=en


See also

*
Sheep shearing Sheep shearing is the process by which the woollen fleece of a sheep is cut off. The person who removes the sheep's wool is called a '' shearer''. Typically each adult sheep is shorn once each year (a sheep may be said to have been "shorn" or ...
* Staple (wool) *
Wool Wool is the textile fibre obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have properties similar to animal wool. ...
* Wool bale *
Wool measurement A micron ( micrometre) is the measurement used to express the diameter of wool fibre. Fine wool fibers have a low micron value. Fibre diameter is the most important characteristic of wool in determining its value. Every fleece comprises a very ...
*Wool-sorter's disease, a historical name for
anthrax Anthrax is an infection caused by the bacterium '' Bacillus anthracis''. It can occur in four forms: skin, lungs, intestinal, and injection. Symptom onset occurs between one day and more than two months after the infection is contracted. The s ...


References

Sheep wool Animal husbandry occupations