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Cotton is a soft fiber that grows around
the seeds of the
cotton plant . The fiber is most often spun into
thread and used to make
a soft, breathable
textile. Cotton is
a valuable crop because only about 10% of the raw weight
is lost in processing.
Once traces of
wax,
protein, etc. are removed, the remainder
is a natural
polymer of pure
cellulose.
This cellulose is arranged in a way that
gives cotton unique properties of strength,
durability, and absorbency. Each fiber is
made up of twenty to thirty layers of cellulose
coiled in a neat series of natural springs.
When the cotton boll (seed case) is opened
the fibers dry into flat, twisted, ribbon-like
shapes and become kinked together and interlocked.
This interlocked form is ideal for spinning
into a fine
yarn.
History
Cotton has been used to make very fine
lightweight
cloth in
areas with tropical climates for millennia.
Some authorities claim that it was likely
that the
Egyptians had cotton as early as 12,000
BC, and they have found evidence of cotton
in
Mexican caves (cotton cloth and fragments
of fiber interwoven with
feathers and
fur) which
dated back to approximately 7,000 years
ago. There is archaeological evidence that
people in South America and India domesticated
independently different species of the cotton
plant thousands of years ago.
The earliest written reference is to
Indian
cotton. Cotton has been grown in India for
more than three thousand years, and it is
referred to in the Rig-Veda, written in
1500 BC. A thousand years later the great
Greek historian Herodotus wrote about Indian
cotton: "There are trees which grow
wild there, the fruit of which is a wool
exceeding in beauty and goodness that of
sheep. The Indians make their clothes of
this tree wool."
By the end of the 16th century
BC, cotton had spread to
warmer regions in Americas,
Africa and Eurasia.
The
Indian cotton industry was
eclipsed during the British
Industrial Revolution, when
the invention of the
Spinning
Jenny (1764)
and Arkwright's
spinning frame
(1769) enabled cheap mass-production
in the UK. Production capacity
was further improved by
the invention of the
cotton
gin by
Eli Whitney in 1793.
Today cotton is produced
in many parts of the world,
including Europe, Asia,
Africa, the Americas and
Australia, using cotton
plants that have been selectively
bred so that each plant
grows more fiber. In 2002,
cotton was grown on 330,000
km of farmland. 47 billion
pounds (21 million t) of
raw cotton worth 20 billion
dollars US was grown that
year.The cotton industry
relies heavily on chemicals
such as fertilisers and
insecticides, although
some farmers are moving
towards an organic model
of production, and
chemical-free organic
cotton products are now
available. Historically,
one of the most
economically destructive
pests in cotton
production has been the
boll weevil.
Most cotton is harvested
mechanically, either by
a
cotton picker, a machine
that removes the cotton
from the boll without
damaging the cotton
plant, or by a cotton
stripper which strips
the entire boll off the
plant. Cotton strippers
are generally used in
regions where it is too
windy to grow picker
varieties of cotton and
generally used after
application of a
defoliant or natural
defoliation occurring
after a freeze. Cotton
is a perennial crop in
the tropics and without
defoliation or freezing,
the plant will continue
to grow. Cotton is a
close relative of okra
and hibiscus.
The logistics
of cotton
harvesting
and processing
have been
improved
by the development
of the
cotton module
builder,
a machine
that compresses
harvested
cotton into
a large
block, which
is then
covered
with a tarp
and temporarily
stored at
the edge
of the field.
Uses
In addition
to the textile
industry,
cotton is
used in
fishnets,
coffee filters,
tents and
in bookbinding.
The first
Chinese
paper was
made of
cotton fiber,
as is the
modern US
dollar bill
and federal
stationery.
Fire hoses
were once
made of
cotton.
Denim,
a type of
durable
cloth, is
made mostly
of cotton,
as are
T-shirts.
The cottonseed
which remains
after the
cotton is
ginned is
used to
produce
cottonseed
oil,
which after
refining
can be consumed
by humans
like any
other vegetable
oil. The
cottonseed
meal
that is
left is
generally
fed to livestock.
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What is Mercerized Cotton?
What is a
bumper crop?
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Genetically modified
cotton
GM cotton was developed
to reduce the heavy reliance
on pesticides. GM cotton
is widely used throughout
the world with claims of
requiring up to 80% less
pesticide than ordinary
cotton. The
International Service for
the Acquisition of Agri-Biotech
Applications (ISAAA)
said that worldwide GM cotton
was planted on an area of
67,000 km
in 2002. This is 20% of
the worldwide total area
planted in cotton. The US
cotton crop was 73% GM in
2003.
The introduction
of GM cotton proved to be
a commercial disaster in
Australia - the
yields were far lower than
predicted, and the cotton
plants cross-pollinated
with other varieties of
cotton potentially causing
many legal problems for
unsuspecting farmers. However
the introduction of a second
variety of GM cotton led
to 15% of Australian cotton
being GM in 2003 with an
expectation of 80% in 2004
when the original variety
will be banned
Organic cotton
Organic cotton is cotton
grown without pesticides
or chemical additives to
fertilizer, relying
instead on methods with
less ecological impact
(http://www.sustainablecotton.org/bASIC/index.html).
Organic cotton is used
to manufacture
everything from
handkerchiefs to kimono
robes. Different levels
of certification
(http://www.ams.usda.gov/nop/indexIE.htm)
exist, but at a minimum,
a crop must be grown in
soil that has been
chemical-free for at
least three years.
Cotton Processing
After
cultivation,
cotton is harvested
at the farm, and goes through
multiple processes.
Before processing, there
are 3 stages:
Ginning
Spinning
Weaving
After weaving, cotton
typically fabric passes
through several processing
stages. After some stages
the fabric can be directly
used in the final product,
for example unbleached cloth
is used in grain bags. Typical
stages are:
Singeing
Desizing
Scouring
Bleaching
Mercerizing
Dyeing
Finishing
Old British cotton yarn
measures
- 1 thread = 54 inches
(c. 137 cm)
- 1 skein or rap =
80 threads (120 yards
or c. 109 m)
- 1 hank = 7 skeins
(840 yards or c. 768
m)
- 1 spindle = 18 hanks
(15,120 yards or c.
13.826 km)
Fair trade
Cotton is an enormously important commodity
throughout the world. However, many farmers
in developing countries receive a low price
for their produce, or find it difficult
to compete with developed countries. This
has led to 'fair
trade' cotton clothing being available
in some countries.
Cotton Gin
Organic Cotton
Women's Cotton Clothing
fabric Definition
fiber Definition
Flannel Definition
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