- Fibre fineness or diameter
- Length
- Age of the animal
- Location of the fibre
- Natural colour
- Sheep breed
- Conditions under which animal lived
An average of 8 pounds of wool is clipped from a sheep in a year and after cleaning and scouring it reduces 5 kgs of wool.
Lamb’s wool It refers to the first fleece sheared from a lamb of six to eight months old. This fibre is fine and soft due to the age of the lamb and tapered ends of hair that are not shorn earlier. Lamb’s wool is generally used for children’s clothing.
Hogget wool Refers to the fleece obtained from sheep of 12 to 14 months old that have not been shorn previously. The fiber is fine, soft, matured, strong, resilient.
Wether wool Refers to any fleece clipped after the first shearing from matured animal. It lacks the softness of hogget wool and is soiled.
Pulled wool Refers to the hair pulled from the sheep after slaughtering the animal for meat. This wool is considered as inferior wool as the animal raised for slaughtering will not have good quality wool and also the use of chemicals for pulling damages the roots.
Dead wool Refers to wool that has been recovered from sheep that have died on the range or killed accidently. This grade is considered inferior.
Cotty wool It is obtained from the sheep that are exposed to severe weather conditions or malnourished. The fiber is hard and brittle and resembles cotton, hence the name.
Taglocks This refers to an inferior grade of wool fleece that has been torn, ragged or discoloured. Taglocks are marketed separately.
Irrespective of the breed of the sheep, superior wool is found to grow longer, finer and softer on sides and shoulder of the animal. Wool obtained from the head, chest, belly and shanks is considered little inferior and treated as a second fleece.
Manufacture The weight of the fleece varies one animal to other and an average of 3.5 kgs is obtained from each healthy sheep. The fleece after shearing is trimmed and packed in bales and sent to scouring and spinning centers. In the scouring and spinning centers wool obtained from different bales is processed as follows:
Sorting and grading Wool is obtained from different sheep farms is opened and sorted as per the grade. Skilled workers are capable of sorting wool by sight and touch upto 20 grades if required. The grade is determined by type length, fineness, elasticity and strength of the wool fibers.
Garnetting It is common to use recycled wool obtained from used and unused wool materials. Garnetting is a picking and shredding process thereby reducing these materials into a fibrous mass. The fibers are put through a carbonizing bath (dil solution of HCl/H2SO4) in order to burn any vegetable matter present. The quality of the extracted fibre depends on the quality of its original stock. Sometimes it may be 4 to 5times costlier than new/virgin wool.
Scouring The raw wool contains impurities such as dirt, grease, other vegetable matter etc which needs to be removed before it is carded and spun. Therefore the raw wool is subjected to scouring which is thorough washing in an alkaline solution. The scouring liquor contains warm water, soap and a mild solution of soda ash or other mild alkali. The scouring is carried out in machines or vats equipped with automatic stirrers which stir the wool continuously and remove the impurities. Thorough washing and squeezing is done with roller between the vats. If the wool is heavily soiled, raw wool will also be put through carbonizing.
Drying After scouring, wool is allowed to dry but not completely as it becomes unmanageable. Hence 12-16 % of moisture will be left in the fibre.
Oiling To manage the dried wool by making it soft and lubricant, oil will be sprayed.
Dyeing It is uncommon to find wool dyed in stock. This is the stage at which dyeing take place if the dyed fibre is required. The stock dyed fibers absorb maximum colour and show superior colour fastness properties.
Blending Different grades of wool will be blended at this point of manufacture. Depending upon the quality of the final product required, fine and superior wool may also be blended with coarser and inferior wool to make it inexpensive. To produce blended fabrics, wool is blended with other fibers also.
Carding Carding is an essential process of disentangling the fibers and making them parallel to each other to facilitate spinning. Wool carding introduces the classification of woolen and worsted yarns based on the end use. Woolen yarns are used for making woolen fabrics that are soft, fuzzy and thick in nature and utilized for warm textiles. Worsted fabrics are fine in nature and used for making durable clothing.
For production of fuzzy woolen yarns, carding is carried out to disentangle the fibbers, but it is not desirable to make them parallel to each other. Another and thin films of fibers or sliver is placed diagonally and overlaps the other sliver by an oscillating device to produce criss cross effect reducing the parallelism. After carding, the sliver becomes fuzzy and it will be directly taken to the spinning frame for further processing.
Wool fibers intended for manufacture of worsted yarns undergo carding for the purpose of disentangling the fibers and also make them parallel to each other, so that fine and smooth yams are produced after spinning. These slivers undergo further processing to make them strong.
Gilling and combing The carded wool intended for worsted stream is subjected to extra processing such as grilling and combing. The essential purpose of both the processes is to remove short fibers and make the long fibers parallel to each other. This process is continued after gilling as combing operation wherein short fibers of 1-4 inch(called combing noils) are removed and fibers over 4 inch (called wool tops) are thoroughly combed to make them assume high degree of parallelism needed for producing strong yarns suitable for suiting fabrics. Wool tops excel in colour, feel and strength as compared to short wool noils. However, wool noils may also exhibit good quality based on the origin and may be employed as filler in other fabrics as recycled wool.
Drawing Worsted yarns alone undergo drawing operation wherein the carded slivers are doubled and redoubled to produce uniform sliver. The process is continued by drawing the sliver, drafting and giving first twist to hold the fibers during spinning and winding them on spools.
Roving Light twisting of the sliver is continued and roving is the final stage before spinning. However roving has no tensile strength and if pulled the fibre separate.
Spinning
The spinning frames finally make the wool yarn by attenuating the roving to the required size and twist based on the end use of the final yarn. Woolen yarns are given slack twist mainly on mule frame. Worsted yarns may be spun using any type of spinning frame such as mule, ring, cap, and flyer. Based on the end use of worsteds, the fibers may be oiled before combining and inserted tight twist or very light twist is inserted without oiling.
The differences between woolen and worsted yarns are
| Woolen yarn
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Worsted yarn
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Consists of short stable fibers
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Consists of long staple fibers
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Carded only
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Carded and combed
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Slack twisted
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Tightly twisted
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Bulky fabrics
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Fine, smooth, sturdy fabrics
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Weaker fabrics
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Stronger fabrics
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Mainly providing for warmth
Ex. Jackets, sweaters, blankets etc.
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Besides being warmth, provides durability Ex. Coats, suits, business wear etc.
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