Wool: production, properties and uses
Wool is the protein (keratin) hair of sheep. Its scales and crimp make it warm, springy and absorbent, but also make it felt and shrink with heat, water and rubbing.
From fleece to yarn
- 1Shearing: the fleece is clipped from the live sheep, usually once or twice a year, often in one piece.
- 2★Sorting and grading: the fleece is split by quality; shoulders and sides give the best wool, the legs the coarsest. Grades depend on fineness, length, colour and crimp.
- 3★Scouring: washing in warm water with soap and mild alkali (soda ash) removes grease, dried sweat (suint) and dirt. The grease is recovered as lanolin for creams and ointments.
- 4Carbonising: dilute sulphuric acid destroys burrs and plant bits; wool resists acid, so the fibre is unharmed. The charred bits are crushed and dusted out.
- 5Drying and oiling: a little oil is added so fibres do not break in carding.
- 6Carding: fibres are opened into a web and gathered into a soft rope (sliver). Woollen yarn is spun straight from carded sliver.
- 7Combing (for worsted only): short fibres (noils) are removed and long fibres laid parallel; drawing and spinning then give smooth worsted yarn.
★ one-way, controls the pace
Woollen and worsted yarns
Properties of wool
| Property | Wool | So in use |
|---|---|---|
| Structure | Overlapping surface scales; natural crimp; a cortex, with a hollow medulla in coarse wool | Scales cause felting; crimp traps air |
| Warmth | The best insulator of the natural fibres: crimp holds still air | Sweaters, shawls, blankets |
| Absorbency | Highest regain (about 13-16%); still feels dry when damp | Comfortable in cold, damp weather |
| Strength | Weakest common natural fibre; weaker still when wet | Never wring or rub wet wool |
| Elasticity and resiliency | Excellent; springs back | Resists wrinkles; creases hang out overnight |
| Felting shrinkage | Scales lock together with heat, moisture, rubbing and alkali | Wash in lukewarm water with mild detergent; squeeze, do not rub |
| Chemicals | Dissolves in hot caustic soda; damaged by chlorine bleach; resists dilute acids | Use mild, neutral soap |
| Insects and flame | Eaten by moth and carpet-beetle larvae; burns slowly and goes out on its own | Store clean with neem leaves or naphthalene balls |
Uses and Indian wools
- Clothing: sweaters, cardigans, shawls, suits, socks, caps and uniforms for cold regions.
- Household: blankets, carpets and rugs (Bhadohi in Uttar Pradesh is a carpet hub), upholstery.
- Felts: hats, slippers, pads and Kashmiri namda rugs.
- Specialty hair: pashmina (cashmere) from the Changthangi goats of Ladakh; Kullu shawls from Himachal Pradesh.
- Label terms: virgin (new) wool; reprocessed wool (from unused scraps); reused wool (from old garments). Panipat in Haryana is a large centre for re-spinning woollen waste into blankets.
Wool keeps elderly people and babies warm in cold weather, but wash it in lukewarm water without rubbing to avoid felting. Wool burns slowly and goes out on its own, so it is safer near heaters and stoves than acrylic, which melts and keeps burning.
2 marks: “Differentiate woollen and worsted yarn.” Woollen yarn is carded only, soft, fuzzy and bulky; worsted yarn is carded and combed, smooth, strong and fine.
5 marks: “Explain why wool shrinks and felts. How can it be prevented?” Surface scales lock under heat, moisture, agitation, pressure and alkali, and fibres cannot move back. Prevent: lukewarm water, mild soap, no rubbing; shrink-resist (chlorine or resin) finishes.
10 marks: “Describe the processing of wool from fleece to yarn, with its properties and uses.” Shearing, sorting, scouring (lanolin), carbonising, oiling, carding, combing (worsted); properties table; uses and Indian examples.
Wool steps start with S-S-S-C: Shear, Sort, Scour, Carbonise. Felting needs H-M-A-P: heat, moisture, agitation, pressure.