UNIT 5
WOOL

WOOL
Prepared by –
Biniya Arakkal
Textile Science Faculty
Institute of Design & Technology
Surat

About - Wool
 Wool is natural animal fiber obtained from sheep.
 It is composed of protein substance – Keratin.
 Wool composed carbon, hydrogen, nitrogen & sulfur
 It has crimps & curls thus gives a spongy feel as well
as insulation for the wearer.
 Color of fiber ranges from white to brown.
 Removing wool from sheep is known as shearing.
 After shearing, the wool is graded & scoured in
alkaline solution.

Wool

Sheared Wool
Scouring in
Alkaline Solution

Woolen & Worsted

Wool
 Next process is done depending upon woolen fabric
or worsted products are to be made.
 Wool is having low strength
 Its water repellant and the water droplets can be
brushed off easily from surface, it absorbs about 20%
of water without feeling damp.
 The fabrics of wool are intended for winter purpose
because of its good insulating property.

Characteristic of Wool
The characteristic of protein fiber - wool
 They are composed of amino acids.
 They have excellent absorbency.
 Moisture regain is high.
 They tend to be warmer than others as they are bad
conductors of heat.
 Only natural fiber which has low tenacity or strength.
 They have poor resistance to alkalis but good
resistance to acids.
 They have good elasticity and resiliency.

Classification by Fleece
1. Lamb’s Wool – The fleece obtained by shearing the lamb is
six to eight months old for the first time is known as lamb’s
wool (First Clip). It has natural tapered end that gives it a
softer feel.
2. Hogget Wool – This is the one obtained from the sheep
about 12 to 14 months old that have not been previously
shorn. The fiber is fine, soft, resilient and mature and has
tapered ends.
3. Wether Wool – It is the one obtained from the sheep older
than 14 months. The shearing is not done for the first time
and in fact these fleeces are obtained after first shearing.
4. Pulled Wool – It is taken from animals originally
slaughtered for meat. The wool is pulled from the pelt of the
sheep using various chemicals. It produce low-grade cloth.

Classification by Fleece
5. Dead Wool – This is wool obtained from the sheep that
have died of age or accidentally killed. Dead wool fiber is
decidedly inferior in grade.
6. Cotty Wool – This type of wool is obtained from the sheep
that are exposed to severe weather. The cotty wool is of a
poor grade and is hard and brittle.
7. Tag Locks – The torn, ragged, or discolored parts of a
fleece are known as tag locks. These are usually sold
separately as an inferior of wool.
Cotty WoolTag Locks

Manufacturing process of Wool
Scouring
Carding
Spinning
Woolen Yarns Drawing
Roving
Spinning
Sorting &
Grading
Drying Oiling
Ginning & Combing
Worsted Yarns
Preparation of the
Fibers

Process
Preparation of Fiber
 Fleece vary from 3 to 8 Kg in weight. The best quality wool is
obtained from the sides and shoulders and is treated as one fleece.
 The raw wool or newly sheared fleece is called grease wool as it
contains natural oil.
 The wool obtained should be carefully sorted into different grades.
Sorting and Grading
 Wool is sorted into sections of different quality fibers, from different
parts of the body.
 The best quality of wool is used for clothing; the lesser quality or
second quality is used to make rugs.

Process
Scouring is the first step in conversion of greasy wool
into a textile product.
It is the process of washing wool in hot water and
detergent.
Machine contains warm water, soap and mild
solution of soda ash or other alkali.
If the raw wool is not sufficiently clear of vegetable
substance after scouring, it is put through the
carbonizing bath of dilute sulfuric acid or
hydrochloric acid to burn out the foreign matter.

Process
Drying
Wool after scouring should not be allowed to become
absolutely dry. About 12 to 16% of moisture is left in
the wool which would enable handling of the fibers in
further processing.

Process
Oiling
Wool is unmanageable after scouring and hence the
fiber requires to be treated with various oils to keep it
from becoming brittle. It also helps to lubricate for
spinning operation.

Process
Carding is the process which depends up on whether woolen yarn or
worsted yarns are to be produced.
Manufacturing Woolen Yarn, the fiber passes through two stages
 Carding
 Spinning
Carding:- Objective of carding is to disentangle the fiber
 The wool fiber is passed between rollers covered with thousands of
fine wire teeth.
 Fibers are disentangled by the action of wires and are arranged
parallel.
 By using oscillating device, one thin film, or sliver of wool is placed
diagonally and overlapping another sliver to give a fuzzy surface.
Spinning:- This stage is similar to that of worsted production process.

Process
Manufacturing Worsted Yarns has involved different steps.
 Carding
 Gilling and Combing
 Drawing
 Roving
 Spinning
Carding:- This process is carried out in same way as carding process for
woolen yarn.
Gilling and Combing:- Gilling is carried out before (Preparative gilling) and
after (Finisher gilling) combing.
 Preparative gilling is mainly to align the fibers in parallel direction, blend
the wool through doubling and to add moisture & lubricants.
 Finisher gilling is mainly aimed to remove the mild entanglement
introduced to the combed sliver.
 Gilling process removes the shorter staple and straightens the longer fibers.
 Combing removes shorter fibers 1 to 4” length (Comb noils), places longer
fibers(tops) parallel.

Principle system of spinning
There are two principle system of spinning worsted
yarn, they are;
English System:- In English system(Bradford), the
fiber is oiled before combing and a tight twist is
inserted. This produce smoother and finer yarns.
French System:- In this system, no oil is used.
Yarn is given no twist, it is fuzzier therefore it is soft
worsted yarn.

Principle System Of Spinning
Worsted yarn Fabric
Woolen yarn Fabric

Woolens Worsteds
Processing – spun from wool fibers of
oLength – spun from short fibers of 1-3”
oDiameter- medium or coarse
The fibers are washed, scoured & carded.
Processing – spun from wool fibers of
oLength – longer than 3”
oDiameter- fine diameter.
Fibers are washed, scoured, carded, combed and
drawn.
Yarn
Bulky
Uneven
Low to medium slack twist
Tensile strength lower than worsted
Yarn
Fine
Smooth
Even
Tighter twist
Higher tensile strength
Fabric appearance
oSoft
oFuzzy
oHeavier weight
Fabric appearance
oCrisp
oSmooth
oLighter weight
Characteristics
Insulator due to trapped air
Doesnot hold a crease well
Less durable than worsted
Characteristics
Less insulator
Holds creases and shape
More durable than woolens.
Uses
oSweater
oCarpets
oTweeds
Uses
oSuits
oDresses
oGabardines

Gabardines

Crepes

Characteristics of Wool Fabric
1. Composition: The chief constituent is protein substance called Keratin.
Chemically it contains carbon, hydrogen, oxygen, nitrogen and sulfur.
2. Strength: Wool is the weakest fiber. Fabric is strengthened by the use of
ply yarns. It loses about 25% strength when wet
3. Elasticity: Each wool fiber is a molecular coil-spring making the fiber
remarkably elastic. It can be stretched 25 to 30% of natural length and
stretch up to 50% when wet.
4. Resilience: Wool is the most resilient fiber because it has a natural crimp
that keeps its shape.
5. Drapability: Wool’s excellent draping quality is aided by its pliability,
elasticity and resiliency.
6. Heat Conductivity: Wool fibers are non-conductor of heat, they permit the
body to retain its normal temperature. It is natural insulator and keeps
body warm in winter.

Characteristics of Wool Fabric
7. Absorbency: Wool fiber is original wicking fiber. Wool can be easily absorb
up to 30% of its weight in moisture without feeling damp.
8. Cleanliness and Washability: The wool adheres dirt and requires
thoroughly cleaned. Care should be taken while laundering as the fiber is
softened by moisture and heat which results in shrinking.
9. Reaction to Bleaches: Chlorine bleaches like sodium hypochlorite are
harmful for wool. They can be bleach by hydrogen peroxide or sodium per
borate.
10.Shrinkage: Wool shrink when washed.
11. Effect of Heat: Wool becomes harsh at 100C and begins to decompose at
slightly higher temperature. It does not burn freely when touched by flame.
12.Effect of Light: Wool is weakened by prolonged exposure to sunlight.

Characteristics of Wool Fabric
13.Resistance to Mildew: Moisture is the main factor for the development of
mildew on a fabric. When fabric is left damp condition, mildew develops.
14.Resistance to Insects: Wool are especially vulnerable to the larvae of moths
and such other insects as carpet beetles.
15.Reaction to Alkalis: Wool is quickly damaged by strong alkalis, which make
it essential to use mild soap or detergent.
16.Reaction to Acids: Although wool is damaged by hot sulfuric acid, it is not
affected by other acids.
17.Affinity for Dyes: The dye reaches the core of the fiber and bonds
permanently. It absorbs many different dyes deeply, uniformly and directly
without use of combining chemicals.
18.Resistance to Perspiration: Wool is weakened by alkali perspiration.
Perspiration generally will cause discoloration

Laundry
 Wool laundered using mild detergent or shampoo as
alkaline solution is harmful
 Do not wring them for removing water, but can be
rolled between the towel or absorbent pad.
 Can be placed flat on paper to retain its original
position .

Storage
 Wool should be stored in clean and dry vaccum bags
with naphthalene balls to avoid the damage by
moths, mildew and insects attack.

Woolen fabrics

Worsted fabric

Summary
 Wool fibers are animal fibers, which are obtained from sheep.
 Wool, after shearing, it is graded and then scoured with
alkaline solution. Then it is subjected to next process
depending upon whether it is meant for worsted purpose or
woolen products.
 These are the only natural fibers, which have considerable low
strength.
 The color of fiber ranges from white to brown depending upon
the nature of sheep from which it is sheared.
 It is water repellent and the water droplets can be brushed off
easily from the surface, it can also absorb about 20% of its
water without feeling damp.
 These fabrics are best intended for winter purpose.