Wool

The Wool Fiber

1.

Growth A. Wool fibers grow from follicles in the skin.

B. Growth and elongation occurs at the base of the fiber and not at the tip.

C. The processes of growth are continuous.

D. Shearing apparently does not particularly stimulate growth of wool fibers.

The Wool Fiber

2. Feature of Wool Fiber A. Diameter may vary from .0003 to .002 inch.

B. Number of fibers per square inch may vary form 5000 to 50,000.

C. Length may vary form 1 to 20 inches.

D. Practically all wool has crimp. Crimp is the natural indentation of waviness in the fibers. The number of crimp per inch of fiber ranges form 10-36. Crimp affects the length of wool may increase length by 30%. In general, the more crimp per inch, the finer the fiber.

E. Wool has a high tensile strength, 17 tons per square inch of fiber.

F. Elasticity due primarily to the cystine content of the fiber partly to the crimp.

The Wool Fiber

3. Chemical Composition —Considerable variation.

A. Pure wool is composed mainly of Keratin, an insoluble protein, which is the chief constituent of hair, feathers, horns, and hooves. B. Cystine is the main constituent of Keratin (about 13%). It is in the cystine that sulfur is present in the wool. (sulfur content of clean wool is about 3.4%).

The Fleece or Grease Wool

1.

Variation of wool fibers on the body.

A. The finest and dense wool fibers are found on the shoulders about midway between the top of the shoulder and the floor of the chest.

B. The shortest wool is on the belly.

2. General characteristics of wool.

A. Wool is not quickly inflammable, but it will burn and give off a very disagreeable odor. B. Electricity and heat transfer through wool slow.

C. Softness of the wool is the opposite to harshness it wiry; sometimes dues to lack of yolk.

D. Purity- purity is related to the kind and color of the fiber of which the fleece is composed. Kemp is the most important of the purity defects. Black fibers may also be called an impurity.

E. Color- color is partly tint ,luster or brightness. White is preferred.

F. Uniformity- Fibers of uniform grade over the badly. Sought but never completely achieved.

3. Adhering material in raw wool.

Some of these are not necessarily disadvantages as they may be essential to the proper preservation of the fiber while it is being developed to a length suitable for use.

A. Yolk- Primarily cholesterol and is secreted for the preservation of the fiber. More yolk is secreted by fine, dense fleeced sheep.

B. Suint-(pronounced swint) A potassium salt produced by the sweat gland. It is usually mixed with yolk. It may be the source of odor associated with sheep.

C. vegetable Matter - such burns, chaff, seed, etc.

D. Dirt- varies from one part of the country to the other.

E. Moisture-gives a certain character to wool which makes it easier to work. I some cases these materials make up a greater percentage of the entire weight than does the wool fiber.

4. Shrinkage

The percentage loss in weight of grease wool due to scouring. Shrinkage varies widely in different fleeces from 20-80%.

A. Estimated shrinkage according to grade Fine Wool Half-blood Three-eights blood Quarter Blood low Medium High 60 61-67 68 56 57-64 65 52 53-59 60 45 46-54 55 Low quarter 40 41-49 50

Shrinkage Con.

B. Range wool shrinks more than farm wool generally because farm wools are coarser.

C. Yield 100% minus shrinkage (in %) = yield D. Grease price = clean wool price x yield E. Clean Price = Grease price x 100 Yield F. Most shrinkage is estimated G. Shrinkage is influenced primarily by dirt and yolk.

5. Classes of wool

Two general classes of apparel wool are combing and clothing wool. This classification is based on length of fiber. Sometimes an intermediate class is used which is called French combing.

– Combing wool—tops worst cloth – Clothing wool –noils As wool increases in coarseness it must also increase in length to be combed.

– Grade Length of necessary for combing Fine 2 ¾” Half blood Three-eights blood Quarter blood Low quarter blood 3” 3 ¼” 3 ½” 4” Clothing wool, 1 ½” shorter: French combing in between

6. Grades of Wool

Grades of wool are based primarily on fineness (diameter of fiber) and variation in fiber diameter. Fine wool makes finer fabrics than coarse wool and usually sell for a higher price per pound, however in the grease, fine wool may sell for less per pound, due to shrinkage.

Grades of wool may be given in either the American or Bradford (English) system. These systems have different terminology, but are based on the relative fineness of fiber.

Grades of Wool Con.

Wool Class Fine American Bradford Fine 80-70-64 Half-blood 62-60 Breed Merino, Ranbouillet, Debouillet Targhee,Southdown Three-eights blood 58-56 Medium Quarter Blood 54-50 Cheviot Corriedale, Columbia, Hampshire Shropshire, Dorset, Low quarter blood 48-46 Romney and coarse crossbreds Common 44-40 Lincoln, Cotswold, Leicester Long Braid 36

7. Factors affecting the value of wool

Clean Wool A.

Grade B.

C.

Grease Wool A. Grade Length B. Length Strength, purity, etc. C. Shrinkage

8. Manufactures of wool

A.

B.

C.

D.

Sorting separating various parts of the fleece according to fineness.

Scouring- a cleaning process- warm water and dilute alkali- which removes dirt, grease, and some vegetable matter.

Carding- clean wool is passed through a machine, which tends to straighten out the fibers. This yarn is usually used for woolen cloth.

Combing- a machine process which draws the fiber out in a parallel direction. Wool must be certain length to comb.

Biological Development of the Wool Fiber

1.

Structure of the skin A. wool fibers are outgrowths of the skin B. skin consists of an outer layer, the epidermis and a much thicker layer, the dermis or corium C. the loose layer of connective tissue beneath the skin is know as the tela subcutanea D. underlying this layer is the panniculus adiposous or subcutaneous fatty tissue

2. General Development of the Individual Skin Follicles

A.

Two types of follicles 1. primary- usually the largest and arranged in rows in the skin in groups of three 2. Secondary-are the most numerous and lie to one side of the primaries B. The primary trio with its associate secondary follicles constitute the follicle group and is known as the basic unit of wool production.

3. Structure of the Fiber

A.

B.

C.

D.

Epicuticle- a thin outer membrane covering the cuticle Cuticle- makes up a protective layer of overlapping, flattened cells, called scales.

1.

2.

Cortex- the major component of the wool fiber and imparts many special properties including elasticity, resiliency, and durability.

Orthocortex- referred to a soft and has a higher affinity for dyes and is found at the outside of the curve of the fiber.

Paracortex-found on the inside of the curve of the fiber and is referred to a the hard and maintains less affinity for dyes.

Medulla- central core-is found primarily in the medium and coarse wools. Medulation is considered to be caused form incomplete keratinization. Basically, the fiber is wider than the follicle’s ability to produce kertain and hollow or spongy core results.

A.

B.

C.

4. Three types of fibers produces by sheep

Wool fibers-true fibers and referred to as crimp or waviness found on the fiber Med- hair or heterotype- medullated and tend to be finer than kemp fibers as well as true fibers , yet generally lack crimp.

Kemp-coarsest fibers grown by sheep and are shed seasonally. Tend s top be short, chalky white, brittle, and do not appear to accept dyes well. They are harsh handling, yet important in the manufacturing of weeds.