Wool - Diff Types of Wool Fabrics and Its Behavior

7/30/2019 Wool - Diff Types of Wool Fabrics and Its Behavior

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Wool

Introduction to Wool and Different

Types of wool fabrics-Prepared by

-P.Lakshmana kanth, Senior Faculty IFTK


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Introduction

Wool is the fiber derived from the fur of animals of theCaprinae family; principally sheep. Wool was probablythe first animal fiber to be made into cloth. The art of

spinning wool into yarn developed about 4000 B.C.

No one knows when man started using wool as a textilefibre. The dense, soft, often curly hair forming the coatof sheep and certain other mammals, such as the goatand alpaca, consisting of cylindrical fibers of keratincovered by minute overlapping scales and much valuedas a textile fabric.


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What is a wool fibre? Wool is a protein fiber and it is

produced by the animals known as

sheep. It is unique fire with scales onits surface.

Wool, is a multi-cellular fiber and very

expensive in price.


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Wool Producers in the World. Australia

Russia New-Zealand

USA

UK

South-Africa

France Turkey

Brazil

China etc.,


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Raw materials In scientific terms, wool is considered to

be a protein called keratin. Its length

usually ranges from 1.5 to 15 inches(3.8 to 38 centimeters) depending onthe breed of sheep. Each piece is made

up of three essential components: the cuticle,

the cortex, and

the medulla.


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The cuticle is the outer layer. It is a protective layer of scales arranged like

shingles or fish scales. When two fibers come in contact with each

other, these scales tend to cling and stick toeach other.

It's this physical clinging and sticking thatallows wool fibers to be spun into thread soeasily.


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The cortex is the inner structure made up ofmillions of cigar-shaped cortical cells.

In natural-colored wool, these cells containmelanin. The arrangement of these cells is also

responsible for the natural crimp unique to

wool fiber.


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Rarely found in fine wools, the medullacomprises a series of cells (similar to

honeycombs) that provide air spaces, givingwool its thermal insulation value.

Wool, like residential insulation, is effective inreducing heat transfer.


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The manufacturing Process The major steps necessary to process

wool from the sheep to the fabric are:

shearing,

cleaning and scouring,

grading and sorting,

carding, spinning,

weaving, and finishing.


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Shearing Sheep are sheared once a year usually in the

springtime.

A veteran shearer can shear up to two hundredsheep per day.

The fleece recovered from a sheep can weighbetween 6 and 18 pounds (2.7 and 8.1 kilograms);as much as possible, the fleece is kept in one piece.

While most sheep are still sheared by hand, newtechnologies have been developed that usecomputers and sensitive, robot-controlled arms to dothe clipping.


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Grading and Sorting Grading is the breaking up of the fleece based on

overall quality.

In sorting, the wool is broken up into sections ofdifferent quality fibers, from different parts of thebody.

The best quality of wool comes from the shouldersand sides of the sheep and is used for clothing; thelesser quality comes from the lower legs and is usedto make rugs.

In wool grading, high quality does not always meanhigh durability.


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Wool is also separated into grades based on the measurementof the wool's diameter in microns. These grades may varydepending on the breed or purpose of the wool.

For example:

< 17.5 - Ultra fine merino 17.6-18.5 - Superfine merino

< 19.5 - Fine merino 19.6-20.5 - Fine medium merino 20.6-22.5 - Medium merino 22.6 < - Strong merino

[Or] < 24.5 - Fine 24.5-31.4 - Medium 31.5-35.4 - Fine crossbred 35.5 < - coarse crossbred


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Breeds of sheep are grouped according to

the type of wool they grow Fine

Rambouillet, Merino Crossbred (fine x medium)

Targhee, Corriedale, Columbia Medium (fine x long)

Suffolk, Hampshire, Dorset,Cheviot, Montadale, Southdown,Shropshire, Tunis, Polypay

Long (coarse)

Romney, Border Leicester,Lincoln, Cotswold Carpet (double-coated)

Scottish Blackface, Karakul,Icelandic

Hair (shedding) - not shearedKatahdin, Dorper, Barbado


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Fleece

Sheared off in one piece

Grease or raw wool is wool asit is shorn from the sheep.


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Cleaning and Scouring Wool taken directly from the sheep is called "raw" or "grease

wool."

It contains sand, dirt, grease, and dried sweat (called suint); the

weight of contaminants accounts for about 30 to 70 percent ofthe fleece's total weight.

To remove these contaminants, the wool is scoured in a seriesof alkaline baths containing water, soap, and soda ash or asimilar alkali.

The byproducts from this process (such as lanolin) are savedand used in a variety of household products.

Rollers in the scouring machines squeeze excess water from thefleece, but the fleece is not allowed to dry completely.

Following this process, the wool is often treated with oil to give

it increased manageability.


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Differences between woolenand Worsted

In the spinning operation, the wool roving is drawn outanti twisted into yarn. Woolen are chiefly spun on themule spinning machine. Worsted yarns are spun on any

kind of spinning machine mule, ring cap or flyer. The differences between woolen and worsted yarns are as

follows:Woolen WorstedShort staple

Carded onlySlack twistedWeakerBulkierSofter

Lang staple

Carded and combedTightly twistedStrongerFiner, smoother, even fibresHarder


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Physical & Chemical Propertiesof Wool


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Fineness fiber diameter

Thickness of the wool fiberMeasured in microns (one millionth of a meter - )


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Fiber diameter

Coarser

C

oarser

BritchBreech(hairy)

Short, dirty, kinky

Short, dirty

Polypay


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Crimp

The natural curl or waviness in the wool fiber.

Fine wool usually has more crimp per inch than coarse (long) wool.


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StapleRefers to the length of a (un-stretched) lock of shornwool.

Coarse woolsare usuallylonger than finerwools.

Fine

Long, coarse

Medium


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Vegetable matter (VM)Any material of plant origin found in

the fleece (hay, grass, seeds, etc.)

High VM lowers yield.


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Tag

Wool that has manure attached to it.


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LanolinA natural oil extracted from sheeps wool.

Also called wool wax, wool fat, or wool grease.

Used to makeointments and

cosmetics.


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SkirtingRemoving the stained, unusable, or undesirable

portions of a fleece (bellies, top knots, tags).

Show fleeces andother high valuefleeces should beskirted at the time ofshearing.

Yi ld


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YieldThe amount of clean wool that remains afterscouring. Expressed as a percentage.

Wool yield is quitevariable: 40 to 70%.

Long wools have higheryields than fine wools,

due to less grease.

Bulky fleeces havehigher yields.

Clean wool yield = Raw wool shrinkage (VM, grease, impurities)


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Vegetable matter affects yield

Other contaminants: soil, dust, polypropylene from tarps, feed sacks,and hay baling twine, paint, skin, external parasites, and foreign objects.


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Length

Look for uniformity of length

Staple length adds weight to the fleecemore than any other characteristic.


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Quality or fineness

Appropriate grade for breed or type.

Look for uniformity of grade (fineness).

Finer wools are permitted less variability.


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Soundness (strength)Tender wool is wool that is weak and/or

breaks due to poor nutrition or sickness.

This wool does not have a break or tender spot.


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PurityFreedom from pigmented fibers, hair and kemp.

Black fiber/hairsHairKemp

The commercial woolmarket favors whitewool that can be dyedany color.

From a hair sheep


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CharacterGeneral appearance of a fleece:

crimp, handle, and color.


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Weathered tipsAffects dyeing

Tippy wool


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1. Strength

Wool fibres are weak but wool fabrics are verydurable.

The durability of wool is the result of the excellentelongation and elastic recovery of the fibres.

Fibre strength is not always an indication of durabilitysince flexibility of the fibre and its resistance toabrasion is also important.

The tear strength of wool is poor. Wool is fairabrasion resistance.

Flexibility of wool is excellent.

They can be bent back on themselves 20,000 timeswithout breaking.


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2. Resilience

Wool is a very resilient fibre. Its resiliency is greatestwhen it is dry and lowest when it is wet.

It a wool fabric is crushed in the hand, it tends tospring back to its original position when the hand isopened.

Because wool fibre has a high degree of resilience,wool fabric wrinkles less than some others; wrinkles

disappear when the garment or fabric is steamed.

Good wool is very soft and resilient, poor wool isharsh. When buying a wool fabric, grasp a handful todetermine its quality.


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3. Heat Conductivity

As wool fibres are poor conductor of heat, theypermit the body to retain its normal temperature.

Wool garments are excellent for winter clothing andare protective on damp days throughout the year.

The scales on the surface of a fibre and the crimp inthe fibre create little pockets or air that serve asinsulative barriers and give the garment greater

warmth.


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4. Absorbency

Initially, wool tends to be water-repellent.

One can observe that droplets of water on

the surface of wool fabrics are readilybrushed off.

Wool can absorb about 20% of its weight inwater without feeling damp; consequently,

wool fabrics tend to feel comfortable ratherthan clammy or chilly.

Wool also dries slowly.


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5. Cleanliness & Wash-ability

Dirt tends to adhere to wool fabric.

Consequently, wool requires frequent dry cleaning orlaundering if the fabric is washable.

Extreme care is required in laundering.

Wool is softened by moisture and heat, and shrinkingand felting occur when the fabric is washed.

Since wool temporarily loses about 25% of itsstrength when wet wool fabrics should never bepulled while wet.


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6. Effect of Heat

Wool becomes harsh at 212F (100C) andbegins to decompose at slightly higher

temperatures. Wool has a plastic quality in that it can be

expressed and shaped at steam temperature,whether in fabric as for slacks and jackets, or

in felt, as for hats.


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7. Effect of Light - Wool is weakened byprolonged exposure to sunlight.

8. Resistance to Mildew - Wool is notordinarily susceptible to mildew, but if left ina damp condition, mildew develops.


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9. Reaction to Alkalis

Wool is quickly damaged by strong alkalis.

The alkali test can be used to identify wool and woolblends.

The wool reacts to the alkali by turning yellow, thenbecoming stick and jellylike, and finally going intosolution.

If the fabric is a blend, the wool in the blend willdisintegrate, leaving only the other fibres.

Mild alkali-in warm or cool water-can is used inscouring the raw wool fibres to remove grease.


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10. Reaction to Acids

Although wool is damaged by hot sulphuricacid, it is not affected by other acids, even

when heated. Acids are used in the manufacture of wool

fabrics to remove cellulose impurities, such asleaves or burrs that may still be in the fabric

after weaving. This treatment is called carbonizing.


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11. Affinity for Dyes

Because of their high affinity for dyes,wool fabrics dye well and evenly.

The use of chrome dyes assuresfastness of colour.

A variety of other dyes may be

effectively used.


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12. Resistance to Perspiration

Wool is weakened by alkali perspiration.

Garments should be dry cleaned or washed

with care to avoid deterioration and odor. Perspiration, generally, will cause

dis-coloration.


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13. Flammability

Wools burns very slowly and it self-extinguishing.

It is normally regarded as flame-resistant.

For curtains, carpets and upholstery to

be used in trains, planes, ships, hotelsand other public buildings, wool is oftengiven a flame-retardant finish.


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14. Press Retention

Wool also has good press retention. It takes andholds creases well.

Creases are set by use of pressure, heat andmoisture.

During pressing the fibre molecules adjustthemselves to the new position by forming new

cross-linkages. Creases in wool are not permanent, however,

since they can be removed by moisture.


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Different grades of Wool

Different grades of wool are assignednumbers that range from 36-80. (36s-

80s) The higher the number the finerthe fibre.

The grades fall into 4 basic types-

fines, medium,

coarse and

carpet.


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Grades of Wool

The coarsest grades (36-48) includefibres of 30 microns or more in

diameter and 6or more in length. They are ideal for rugged tweeds,

durable coatings, thick dense blankets

and resilient carpets.


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The medium grades (50-60) includefibres of 24-30 microns in diameter and

4.5 -6 inches long. Medium grades are used to make a

wide variety of high quality woolens,

from fine tweeds, dressy flannels andsoft coatings to sweaters, hosiery,knitting yarns and felt.

Grades of Wool


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The finest grades (62-80)include fibresfrom 15-23 microns in diameter and 1.5

4.5 inches in length. Fine wool is used to make worsted

yarns and high quality fabrics,

especially for the menswear industry. Most fine wools come from the merino

sheep, but wool from other breeds is

also used.

Grades of Wool


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The finest of the fine wools is known assuperfine woolsSuper80s, Super100s,

and Super 120s

Grades of Wool


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Behaviour of Wool Fabrics

Wool sheds wrinkles, but can be pressed to holdsharp pleats and folds

It stretches easily, but wont sag, droop or lose its

shape.

It can be styled to drape softly against the body ormanipulated to hold a shape, such as a perfectlyrolled collar or the curved brim of a hat.


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Behaviour of Wool Fabrics Contd...

Wool fiber dyes beautifully, all the way to thecore and it holds the colour forever. It can be

dyed in almost any colourfrom the palest tobright reds.

Wool is strong and durable-it resists abrasionand is difficult to tear. Garments are easy to

keep clean as the dirt sits on the surface ofthe fabric rather than penetrate into the fibre.


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Wool is naturally fire resistant-it is slowto burn and will self extinguish when

the flame is removed. Wool can be made into fabrics that are

thick and dense, but not very heavy.

This is because wools natural crimpadds volume by creating tiny pockets ofair between the fibres.



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Wools natural waviness or crimp gives itmany advantaged over other textile fibres-

elasticity, flexibility, resilience and loft. It can be stretched 30 % and will spring back

to size when the tension is released. Woolgarments will not stretch out of shape, but

will move with the body, making itcomfortable to wear.



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Although wool has many desirablequalities, there are some limitations too.

It has extreme reaction to alkalis, hencebleaches and detergents should be usedwith care.

Wool is only moderately resistant toheat and is easily damaged by incorrectpressing or hot direct heat



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Moth larvae will eat wool; small fuzz balls(pills) tend to form on the surface of wool

fabrics. Softly twisted yarns, loose weaves,woollen fabrics and knits are more prone topilling than worsteds.

Wool fabrics tend to shrink if not washed

carefully. Hand washing or dry cleaning isrecommended. Pressing should always bedone with steamplace a damp cloth over thefabric when pressing



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Wool is one of the easiest fibres to cut and sew.

Other fabrics are difficult to cut and also sew

Mismatched pieces can be nudged together with nosign of a stretch mark or ripple, stitches can beremoved without leaving a hole and unwantedcreases can be made to disappear.

Wool is more difficult to press than other fabrics, but

if done properly, it results in a good appearance.



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Wool fabrics


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Challis

A high quality, light weight , soft cloth,

It is usually made with tightly spun worsted yarnsand a firm plain weave.

It is one of the few printed wools, most often a floralor paisley design against a darker colour.

The original cloth was made in England from acombination of silk and worsted yarns.


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Wool challis drapes beautifully,and is easy to sew. It will nothold a crease, but is well suited

for un-pressed pleats, gathers,cowl necklines, and otherdraped elements Close fittingstyles that put stress on the

seams should be avoided as thefabric tends to pull apart atseams and also puckers. Idealfor making skirts, dresses andscarves.


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Wool Crepe

A popular light weight fabricmade with highly twisted crepeyarns, giving it a crinkled ,

grainy texture. Wool crepe is available in a

variety of weights and qualities.

The fabric drapes well and isbest for styles that are drapedor slightly gathered into loosefullness but may also be usedto make elegant tailoredgarments.


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Woollen flannel

The fabric may have a soft fuzzy nap on one or bothsides.

The warp yarns are stronger and finer than the

filling yarns which are softly twisted to in order toproduce the nap when the fabric is brushed.

The nap adds warmth to the fabric because of theentrapped air pockets.

Good quality flannel is made of fine yarns and a snugtwill weave , while lower quality flannel is made ofthicker yarns and loose twill or even a plain weave.


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Woollen flannel is one ofthe most common wools ,available in a variety of

weights, solid colours andplaids.

It is easy to sew and cutand is used to make

shirts, skirts, dresses andsoftly tailored jackets andsuits.


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Worsted flannel

Worsted flannel is different from the above in that itis made of worsted yarns that are in turn made offiner fibres and better quality wool.

Worsted flannel is given only a slight nap, so it issmoother than woollen flannel.

It is available in various weights , but only a fewcoloursshades of brown, blue, grey and black.


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Patterned weaves and plaidsare not as common as solidcolours or faint length wise

stripes. The fabric has a lot of body

and will hold the shape ofthe garment especially when

supported by good innerconstruction.

Used for menswear


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Gabardine

Gabardine is Spanish in origin and dates back to theMiddle ages when it described a protective cloak.

Today it describes a popular fabric with a smooth

face and a dull sheen made with a tight twill weaveand worsted yarns.

The wrap has twice as many threads per inch as thefilling.

True gabardine has a distinct closely set diagonal ribon the face and a flat, plain back. The angle of thetwill may be 45 or 65 degrees.

The steeper line is more common for menswear,

while the other is for womens-wear.


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Gabardine comes in a range ofweights and qualities. Best gradesare soft and drape well, lesser

grades may feel harsh , rough orstiff.

Gabardine works best with tailoreddesigns that have clean simple

lines and gentle curves becausethe tight weave is difficult to ease.


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Tweed

Tweed is a popular rough textured woollen fabricmade with a 2x2 twill.

Tweed may be woven with checked, striped or

plaid patterns, or it may be mono-coloured,woven with different shades of the same colour.

It is often dyed in the wool, with fibres ofdifferent colours mixed together before spinningto produce yarns with colourful specks and slubs.

The weight varies, but it is usually a thicksubstantial fabric that is suitable for sportsjackets, coats and caps.


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Plaids

Plaids are any fabric with a pattern of multi-coloured bars and stripes that run in both directionsand cross at right angles.

The colours may be muted or bold and the patternmay be large or small.

The original plaids were made in Scotland. Plaids arewoven into a variety of fabrics , from thick double

cloths to elegant worsted suitings.


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Plaids are difficult to work with itdemands extra time, patience and alot of attention to detail.

The lines of the plaids have to matchin both directions if the garment is tobe rated as one of high quality.

The best styles are those which havesimple lines and minimum of seams.

Plaids require extra fabric and a oneway layout.


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Houndstooth

Houndstooth is a very popular broken checkpattern used to make woollen and worsted fabrics ina variety of weights and qualities.

Houndstooth is made with a variation of the twillweave that alternates four yarns to the left and fouryarns to the right.

Most versions are woven in two colours of yarn-one

light and the other dark which are arranged in groupsof four in both directions of the weave.


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The checks vary in size-thesmall pattern is called minihoundstooth.

As it is yarn dyed, the fabriclooks the same on both sides ,so it is easy to confuse

unassembled pieces of fabric. Houndstooth looks great

when paired with a matchingsolid.


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Herringbone

Herringbone is a popular variation of the twill weave,made by changing the direction of the diagonal twillline , so that it zigzags across a fabric at evenly

spaced intervals. The pattern is distinct when the twill lines within one

section are woven with alternating colours.


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Herringbone should betreated as a striped fabricwith a oneway design.

It may not be necessaryto match the stripes atevery seam, but special

attention is required forpatch pockets, pocketwelts, flaps and similardetails

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Wool - Diff Types of Wool Fabrics and Its Behavior

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