Cotton
Fiber
Cotton
Fiber

Outline:
1. Introduction
2. Species and Varieties of Cotton
3. Structure of Cotton Fiber
4. Cotton Fiber from Field to Mill
5. Cotton Grading and Its System
6. Properties
7. End Uses

Introduction
Cotton referred to as the “King of fibers” is most
important textile fiber in the world.
Cotton is a vegetable fiber which surrounds the seeds
of the cotton plant.
Cotton has been cultivated for more than 5000 years.
Cotton plant belongs to the family “GOSSYPIUM”.

Introduction
The cotton fiber is made up of countless cellulose
molecules. Cotton is removed mechanically from the
seed bolls by the cotton ginning. The ginned cotton is
then pressed into bales and sent to the factories to be
spun into yarns.

Cotton Boll
Cotton after
Ginning
Cotton Bales

Species of Cotton
There are four commercially-grown species of cotton:
Gossypium hirsutum – upland cotton, native to Central
America, Mexico
Gossypium barbadense – known as extra-long staple
cotton, native to tropical South America
Gossypium arboreum – native to India and Pakistan
Gossypium herbaceum – cotton, native to Southern
Africa

Structure of Cotton Fiber

Structure of Cotton Fiber

Longitudinal Structure of Cotton Fiber
Tip
Body
Base
1. Base/Root
2. Body
3. Tip

Cross-sections of fibers showing fully developed
primary walls, mature fibers (SEM)

Cross-section of fibers showing partially
developed primary walls, immature fibers
(SEM).

Cross-Sectional Structure of Cotton Fiber
Lumen Wall
1. Cutical
2. Primary Wall
3. Winding Layer
4. Secondary Wall
5. Lumen Wall
6. Lumen

Varieties/Types of Cotton
Commercial cotton may be classified into following
categories with reference to staple length:
1. Very Short Staple Cotton: (Less than & equal 21mm)
2. Short Staple Cotton: (Between 22-25mm)
3. Medium Staple: (Between 26-28mm)
4. Ordinary Long Staple: (Between 29-34mm)
5. Extra Long Staple: (Equal and greater than 34mm)

Varieties/Types of Pak Cotton
MNH-93 (Cotton of Punjab region)
NAYYAB-78 (Cotton of Sindh region)
Organic Cotton
BCI Cotton

Organic Cotton:
It is generally understood as
cotton grown from non
genetically modified plants, that is
”to be grown without the use of any
synthetic agricultural chemicals such
as fertilizers or pesticides”

Ecological footprint
Cotton covers 2.5% the world's cultivated land yet uses
16% of the world's insecticides, more than any other
single major crop.
Chemicals used in the processing of cotton pollute the
air and surface waters.
Residual chemicals may irritate consumers' skin.
Decreased biodiversity and shifting equilibrium of
ecosystems due to the use of pesticides.

Advantages
Protecting surface and groundwater quality
(eliminating contaminants in surface runoff)
Reduced risk in insect and disease control by
replacing insecticide with the manipulation of
ecosystems
Conservation of biodiversity
Eliminate the use of toxic chemicals used in cotton

BCI Cotton:
The Better Cotton Initiative exists “to make global cotton
production;
better for the people who produce it
better for the environment it grows in
better for the sector’s future”

Steps from Seed Boll to Fiber Growth
Growth of Seed Boll
Fiber Growth
inside boll

Cotton from Field to Mill

Picking/ Harvesting
Process

Ginning Process
After picking, the cotton fibers have to be
separated from the seeds by the process of
Ginning.
Generally two types of Ginning methods:
1. Saw Ginning
2. Roller Ginning

Saw Ginning Process

Roller Ginning Process

By-Products of Cotton
The raw cotton passes through several cleaning processes
before it is baled. As a result, the grower obtains valuable
by-products that amount approximately to one-sixth of the
entire income derived from the cotton plant.
Cotton Linters: Short hair like fibers used in making
Regenerated fibers
Hulls: Outside portion of seed, rich in nitrogen, used as
fertilizer
Inner Seeds: Seed inside the hull gives cottonseed oil, used
in cooking and making soap.

Baling of Cotton Fiber

Cotton Grading and Its System
It is also called “Number Grading System”.
Grading is done on the basis of following
factors:
1. Moisture %age
2. Staple Length
3. U.R % (Uniformity Ratio)
4. Floating Fibers
5. Micronaire (Fineness)
6. Trash %
7. Invisible %

Examples of Grading System
Factor Number
Below 9% Moisture 0
Above 1.089’’ Length 25
Above 48% UR 15
Above 19.99% FF 0
Above 4.99 Mic 0
Below 6% Trash 10
Below 1.50% Invisible 10

Universal Grades of Cotton
This grading is done by (U.S.D.A), United States
Department of Agriculture.
Limitations:
Only for Saw Ginned Cotton
Grading on the basis of Trash %
Not applicable for long staple cotton
No consideration for maturity

Properties of Cotton Fiber
1. Fiber Surface and Color: Lustrous/ Creamy White color
2. Tensile Strength:
Tenacity = 3-5 gm/denier
Strength = 40, 000, 20,000 lb per square inch
3. Elongation: Not easily stretch
Elongation at Break = 5-10 %
4. Elastic Properties: Rigid/ Less Flexibility
At 2% Extension ------- 74% Recovery
At 5% Extension ------- 45% Recovery

Properties of Cotton Fiber
5. Specific Gravity: 1.54
6. Effect of Moisture:
Standard Humidity = 8.5 %
7. Effect of Heat: Excellent Resistance
8. Effect of Age: Small loss of strength when stored
9. Effect of Sunlight: Gradual loss of strength when exposure to
sunlight, major effect by Ultra-violet light.
10. Effect of Acids: By hot dilute and cold concentrated acids

Properties of Cotton Fiber
11. Effect of Alkalis: Excellent Resistance
12. Effect of Organic Solvents: Dispersed by Copper
Complexes and Concentrated 70% Sulphuric acid
13. Chemical Properties:
Cellulose = 94%
Remaining Composition:
Protein = 1-1.5%
Pectin = 1%
Mineral substances = 1%
Wax = 0.5%
Small amount of organic acids, sugars, pigments = 2%

End Uses of Cotton
Yarn
Fabric
Garments
Household Items
- Bed Sheets
- Towels
Carpets and Curtains
Hats