WHAT IS COTTON?:
COTTON is defined as white fibrous substance covering seeds harvested from
SEED COTTON (called Kapas in India - Paruthi in Tamil)harvested from Cotton
LINT COTTON (RUIA in Hindi, PANJU in Tamil) is obtained by removing the
seeds in a ginning machine.
LINT COTTON is spun into Yarn, which is woven or knitted into a Fabric.
Researchers have found that cotton was grown more than 9000 years ago.
However large scale cultivation commenced during middle of 17th Century AD.
Many varieties of Cotton are cultivated mainly from 3 important genetic
species of Gossipium.
G. HIRSUTUM - 87% Grown in America, Africa, Asia, Australia Plant grows to a
height of 2 Meters.
G. BARBADENSE- 8% Grown in America, Africa & Asia. Plant grows to a height
of 2.5 Meters with yellow flowers, long fibers with good quality, fibers
with long staple and fineness
G. Arboreum - 5% Perennial plant grows up to 2 meters with red flowers, poor
quality fibers in East Africa and South East Asia.
There are four other species grown in very negligible quantities. Cotton
harvested from the Plant by hand - picking or machine picking is ginned to
remove seeds and the lint is pressed into Bales for delivery to Spinning
Mills. Cotton is Roller Ginned (RG) or Saw Ginned (SG) depending varieties
and ginning practices.
Cotton is cultivated in 75 Countries with an area of 32 Million Hectares.
Cultivation period varies from 175 days to 225 days depending on variety.
Cotton is harvested in two seasons, summer and winter seasons.
Saw ginned cotton is more uniform and cleaner than Roller Ginned Cotton. But
fibers quality is retained better quality in Roller Ginning than Saw Ginning
which has high productivity.
Cotton Fiber is having a tubular structure in twisted form. Now. researchers
have developed coloured cotton also. As on date, percentage of Cotton fiber
use is more than synthetic fibers. But, its share is gradually reducing.
Cotton is preferred for under garments due its comfort to body skin.
Synthetics have more versatile uses and advantage for Industrial purposes.
PROPERTIES OF COTTON
No other material is quite like cotton. It is the most important of all
natural fibres, accounting for half of all the fibres used by the world's
Cotton has many qualities that make it the best choice for countless uses:
Cotton fibres have a natural twist that makes them so suitable for spinning
into a very strong yarn.
The ability of water to penetrate right to the core of the fibre makes it
easy to remove dirt from the cotton garments, and creases are easily removed
Cotton fabric is soft and comfortable to wear close to skin because of its
good moisture absorption qualities.
Charges of static electricity do not build up readily on the clothes.
HISTORY OF COTTON
Nobody seems to know exactly when people first began to use cotton, but
there is evidence that it was cultivated in India and Pakistan and in Mexico
and Peru 5000 years ago. In these two widely separated parts of the world,
cotton must have grown wild. Then people learned to cultivate cotton plants
in their fields.
In Europe, wool was the only fiber used to make clothing. Then from the Far
East came tales of plants that grew "wool". Traders claimed that cotton was
the wool of tiny animals called Scythian lambs, that grew on the stalks of a
plant. The stalks, each with a lamb as its flower, were said to bend over so
the small sheep could graze on the grass around the plant. These fantastic
stories were shown to be untrue when Arabs brought the cotton plant to Spain
in Middle Ages.
In the fourteenth century cotton was grown in Mediterranean countries and
shipped from there to mills in the Netherlands in western Europe for
spinning and weaving. Until the mid eighteenth century, cotton was not
manufactured in England, because the wool manufacturers there did not want
it to compete with their own product. They had managed to pass a law in 1720
making the manufacture or sale of cotton cloth illegal. When the law was
finally repealed in 1736, cotton mills grew in number. In the United States
though, cotton mills could not be established, as the English would not
allow any of the machinery to leave the country because they feared the
colonies would compete with them. But a man named Samuel Slater, who had
worked in a mill in England, was able to build an American cotton mill from
memory in 1790.
GROWING THE COTTON
Cotton plant's leaves resemble maple leaves and flowers look very much like
pink mallow flowers that grow in swampy areas. They are relatives and belong
in the same plant family.
Cotton is grown in about 80 countries, in a band that stretches around the
world between latitudes 45 North to 30 South. For a good crop of cotton a
long, sunny growing season with at least 160 frost-free days and ample water
are required. Well drained, crumbly soils that can keep moisture well are
the best. In most regions extra water must be supplied by irrigation.
Because of it's long growing season it is best to plant early but not before
the sun has warmed the soil enough.
Seedlings appear about 5 days after planting the seeds. Weeds have to be
removed because they compete with seedlings for water, light and minerals
and also encourage pests and diseases. The first flower buds appear after
5-6 weeks, and in another 3-5 weeks these buds become flowers.
Each flower falls after only 3 days leaving behind a small seed pot, known
as the boll. Children in cotton-growing areas in the South sometimes sing
this song about the flowers:
First day white, next day red,
third day from my birth - I'm dead.
Each boll contains about 30 seeds, and up to 500 000 fibres of cotton. Each
fibre grows its full length in 3 weeks and for the following 4-7 weeks each
fiber gets thicker as layers of cellulose build up the cell walls. While
this is happening the boll matures and in about 10 weeks after flowering it
splits open. The raw cotton fibres burst out to dry in the sun. As they lose
water and die, each fibre collapses into what looks like a twisted ribbon.
Now is time for harvesting. Most cotton is hand-picked. This is the best
method of obtaining fully grown cotton because unwanted material, called
"trash", like leaves and the remains of the boll are left behind. Also the
cotton that is too young to harvest is left for a second and third picking.
A crop can be picked over a period of two months as the bolls ripen.
Countries that are wealthy and where the land is flat enough usually pick
cotton with machines - cotton harvesters.
GLOBAL COTTON - VATIETIES - PLANTING AND HARVESTING PERIODS
COTTON AND YARN QUALITY CO-RELATION:
Instead of buying any cotton available at lowest price, spinning it to
produce yarn of highest count possible and selling Yam at any market in
random, it is advisable to locate a good market where Yarn can be sold at
highest price and select a Cotton which has characteristics to spin Yarn of
desired specifications for that market.
ESSENTIAL CHARACTERISTICS of cotton quality and characteristics of
Yarn quality of Yarn are given from detailed experimental investigations.
Some of the important conclusions which help to find co-relation between
Yarn quality and Cotton quality are given below
STAPLE LENGTH: If the length of fiber is longer, it can be spun into
finer counts of Yarn which can fetch higher prices. It also gives stronger
STRENGTH : Stronger fibers give stronger Yarns. Further, processing
speeds can be higher so that higher productivity can be achieved with less
FIBER FINENESS: Finer Fibers produce finer count of Yarn and it also
helps to produce stronger Yarns.
FIBER MATURITY : Mature fibers give better evenness of Yarn. There
will be less end - breakages . Better dyes' absorbency is additional
UNIFORMITY RATIO: If the ratio is higher. Yam is more even and there
is reduced end-breakages.
ELONGATION :A better value of elongation will help to reduce
end-breakages in spinning and hence higher productivity with low wastage of
NON-LINT CONTENT: Low percentage of Trash will reduce the process
waste in Blow Room and cards. There will be less chances of Yarn defects.
SUGAR CONTENT: Higher Sugar Content will .create stickiness of fiber
and create processing problem of licking in the machines.
MOISTURE CONTENT : If Moisture Content is more than standard value of
8.5%, there will be more invisable loss. If moisture is less than 8.5%, then
there will be tendency for brittleness of fiber resulting in frequent Yarn
FEEL : If the feel of the Cotton is smooth, it will be produce more
smooth yarn which has potential for weaving better fabric.
CLASS : Cotton having better grade in classing will produce less
process waste and Yarn will have better appearance.
GREY VALUE: Rd. of calorimeter is higher it means it can reflect
light better and Yam will give better appearance.
YELLOWNESS : When value of yellowness is more, the grade becomes
lower and lower grades produce weaker & inferior yarns.
NEPPINESS : Neppiness may be due to entanglement of fibers in ginning
process or immature fibers. Entangled fibers can be sorted out by careful
processing But, Neps due to immature fiber will stay on in the end product
and cause the level of Yarndefects to go higher.
An analysis can be made of Yarn properties which can be directly attributed
to cotton quality.
1. YARN COUNT: Higher Count of Yarn .can be produced by longer, finer
and stronger fibers.
2. C.V. of COUNT: Higher Fiber Uniformity and lower level of short
fiber percentage will be beneficial to keep C.V.(Co-efficient of Variation)
3. TENSILE STRENGTH : This is directly related to fiber strength.
Longer Length of fiber will also help to produce stronger yarns.
4. C.V. OF STRENGTH : is directly related CV of fiber strength.
5. ELONGATION : Yam elongation will be beneficial for weaving
efficiently. Fiber with better elongation have positive co-relation with
6. C.V. OF ELONGATION: C.V. of Yarn Elongation can be low when C.V.
of fiber elongation is also low.
7. MARS VARIATION : This property directly related to fiber maturity
and fiber uniformity.
8. HAIRINESS : is due to faster processing speeds and high level of
very short fibers,
9. DYEING QUALITY : will defend on Evenness of Yarn and marketing of
10. BRIGHTNESS : Yarn will give brighter appearance if cotton grade
COTTON QUALITY SPECIFICATIONS:
The most important fiber quality is Fiber Length
||Less than 24
||Coarse Below 20
||Medium Count 20s-34s
||Fine Count 34s - 60s
||Superfine Count 80s - 140s
Spinning Count does not depend on staple length only. It also depends on
fineness and processing machinery.
Length is measured by hand stapling or Fibrograph for 2.5% Span Length
2.5%SL (Spun Length) means at least 2.5% of total fibers have length
exceeding this value.
50% SL means at least 50% of total fibers have length exceeding this value.
Length Uniformity is Calculated by 50SL x 100 / 2.5 SL
Significance of UR (Uniformity Radio) is given below:
UR% Classification 50-55
Very Good 45-50 Good 40-45
Poor Below 30 Unusable
M= 50% SL
UHM SL - Average value of length of Longest of 50% of Fibers
UI Uniformity Index
Interpretation of Uniformity Index
Now Uniformity is measured by HVI
Fiber Strength, next important quality is tested using Pressley instrument
and the value is given in Thousands of Pounds per Square inch. (1000 psi)
For better accuracy, Stelometer is used and results are given in grams /
Lately, strength is measured in HVI (High Value Instrument) and result is
given in terms of grams/tex.
Interpretation of Strength value is given below
Strength is essential for stronger yarns and
higher processing speeds.
Fiber Fineness Fiber Fineness and maturity are tested in a conjunction using
Finer Fibers give stronger yarns but amenable for more neppiness of Yarn due
to lower maturity.
Micronaire values vary from 2.6 to 7.5 in various varieties.
FINENESS AND MATURITY
Usually Micronaire value is referred to evaluate fineness of Cotton and its
suitability for spinning particular count of Yarn. As the value is a
combined result of fineness and maturity of Cotton fiber, it cannot be
interpreted, property for ascertaining its spinning Value. This value should
be taken in conjunction with standard value of Calibrated Cotton value.
The following table will explain that micronaire value goes up along with
maturity but declines with thickness of fiber. An Egyptian variety of
Cotton, three samples of High maturity. Low maturity and Medium maturity
were taken and tested. Test results are given below,
Here, Micronaire Value of 4.3 is higher than
3.9 of low maturity cotton Another Greek Cotton was tested and results are
Micronaire Value of 3.8 is higher than 3.2 of
low maturity cotton. Another American Cotton was tested and results are as
Hence, it is essential to know what
Micronaire value is good for each variety of Cotton.
|1.00 and above
|0.95 - 1.0
|0.85 - 0.95
|0.80 - 0.85
|Less than 0.80
Cotton grade is determined by evaluating colour, leaf and ginning
preparation. Higher grade cottons provide better yarn appearance and reduced
Colour is determined by using Nickerson-Hunter Calorimeter. This gives
values Rd (Light or Dark) and +b (Yellowness).
AMERICAN UPLAND COTTONS ARE CLASSIFIED
ACCORDING TO GRADES AS GIVEN BELOW
||STRICT LOW MIDDLING
||STRICT GOOD ORDINARY
Similar grading is done for Light Spotted,
Spotted, Tinged and Yellow Stained Cottons. PIMA cottons are graded I to 9
HOW TO BUY COTTON?
COTTON BUYING is the most important function that will contribute to optimum
profit of a Spinning Mill.
EVALUATION of cotton quality is generally based more on experience rather
than scientific testing of characteristics only.
TIMING of purchase depends on comprehensive knowledge about various factors
which affect the prices.
CHOOSING the supplier for reliability of delivery schedules and ability to
supply cotton within the prescribed range of various parameters which define
the quality of Cotton.
BARGINING for lowest price depends on the buyer's reputation for prompt
payment and accept delivery without dispute irrespective of price
ORGANISING the logistics for transportation of goods and payment for value
of goods will improve the benefits arising out of the transaction.
PROFIT depends on producting high quality Yarn to fetch high prices.
Influence of quality of raw material is very important in producing quality
Yarn. But, quality of yam is a compound effect of quality of raw material,
skills of work-force, performance of machines,- process know-how of
Technicians and management expertise.
A good spinner is one who produces reasonably priced yarn of acceptable
quality from reasonably priced fiber. Buying a high quality, high priced
cotton does not necessarily result in high quality Yarn or high profits.
GUIDELINES FOR COTTON CONTRACTS:
Buyer and seller should clearly reach correct understanding on the following
1. Country of Origin, Area of Growth, Variety, Crop year
2. Quality - Based on sample or
Description of grade as per ASTM standard or sample
For grade only and specifying range of staple length,
Range of Micronaire, range of Pressley value, uniformity,
Percentage of short fiber, percentage of non-lint content,
Tolerable level of stickiness
3. Percentage of Sampling at destination
4. Procedure for settling disputes on quality or fulfillment of contract
5. Responsibility regarding contamination or stickiness.
6. Price in terms of currency, Weight and place of delivery.
7. Shipment periods
8. Certified shipment weights or landing Weights
9. Tolerances for Weights and Specifications
10. Port of Shipment and port of destination, partial shipments allowed or
not, transshipment allowed or not, shipments in containers or Break-bulk
11. Specifications regarding age of vessels used for shipment, freight
payment in advance or on delivery
12. Responsibility regarding Import & Export duties
13. Terms of Insurance cover
14. Accurate details of Seller, Buyer and Broker
15. Terms of Letter of. Credit regarding bank .negotiation, reimbursement
and special conditions, if any
Choose Correct Supplier or Agent:
Apart from ensuring correct terms of Contract, Buyer should ensure that
purchase is made from Reliable Supplier or through a Reliable Agent. Some
suppliers evade supplies under some pretext if the market goes up.
Otherwise, they supply inferior quality Either way buyer suffers.
By establishing long term relationship will reliable Suppliers, Buyers can
have satisfaction of getting correct quality, timely deliveries and fair
It is good to establish long term relationship with a few Agents who
represent reputed Trading Companies in various Cotton Exporting Countries.
They usually give reliable market information on quality, prices and market
trends so that buyer can take intelligent decision. As cotton is not a
manufactured Commodity, it is good to buy from dependable suppliers, who
will ensure supply of correct quality with a variation within acceptable
limits at correct price and also deliver on due date.
In a market with varying market demand situation. Buyers should decide which
counts of Yarn to spin. Buyer can call for samples suitable for spinning
Yarn counts programmed for production. Many spinners plan to do
under-spinning. For Example, cotton suitable for 44s is used for spinning
40s. Some spinners do over-spinning. They buy cotton suitable for 40s and
spin 44s count. But, is advisable to spin optimum count to ensure quality
and also keep cost of raw material at minimum level as for as possible. Some
spinners also buy 2 or more varieties and blend them for optimum spinning.
For' this purpose, a good knowledge to evaluate cotton quality and co-relate
with yarn properties of required specifications. Cotton buyer should develop
expertise in assessing cotton quality. Machine tests must be done only to
confirm manual evaluation.
TAKING RIGHT OPTION:
It is not advisable just to look at price quoted by supplier. Correct
costing should be done to work out actual cost when the cotton arrives at
Mills. Further lowest price does not always mean highest profit for buying.
Profitability may be affected by anyone or more of the following factors.
If the trash is higher, more waste will be produced reducing the Yarn out-
turn and hence profit.
If the uniformity is less, end - breakages will be more reducing
productivity and profitability.
If grade is poor or more immature fibers are found in cotton, the yarn
appearance will be affected and Yarn will fetch lesser price in the market.
If the transit period for transport of cotton is longer, then also
profitability will be reduced due blocking of funds for a longer period and
increased cost of Interest.
Rate of Sales Tax varies from State to State. This must be taken in to
Hence, thorough costing should be worked out before deciding on the quoted
The margin of profit in spinning cotton should be calculated before deciding
on The various options available depending on market conditions should be
The factors to be considered for taking options are as follows.
Count for which demand is good in market
Prices for various counts for which demand exists.
Cost of manufacturing various counts.
Adequacy of machinery for the selected count.
Various varieties of cotton available for spinning the selected count.
Profit margin for each count using different varieties.
Price quoted by different Agents for same variety of selected cotton.
Reliability of supplier for quality and timely delivery.
Apart from the price quoted by the seller, other incidental costs must be
taken into consideration before buying.
a) Duration for goods to reach Buyer's godown from the seller's Warehouse.
If the duration is longer, buyer will incur higher interest charges.
b) Cost of Transportation and taxes.
Resolution of differences
If any discrepancy arises in the quality, weight and delivery periods,
sellers should be willing to resolve the differences amicably and quickly.
In case the matter is referred to Arbitrator, the award of the Arbitrator
must be immediately enforced.
Bench Marks for Easy Reference
It is better if quality bench marks are established for different varieties
so that buying decisions are easy for buyers Following standards have been
found to be appropriate for Strict Middling Grade Cotton of staple 1.3/32".
Staple Length ( 2.5% Spun Length) - Minimum 1.08" or 27.4 mm
Micronaire : Minimum 3.8, Maximum-4.6 Variation within bulk sample should
not be more than _ 0.1
Colour : Rd not less than 75 not more than 10
Nep Content: Less than 150 per gram
Strength : More than 30 grams/tex
Length Uniformity Ratio: Not less than 85%
Elongation : More than 8%
Short Fiber Content: Less than 5%
Seed Count Fragments : Less than 15 per grams
Commercial Bench marks can be given as follows:
Easy Availability throughout year
Uniform Classing and Grading system
Even- running Cotton in all Characteristics
Reliable deliveries Úr Respect for sanctity of contract.
The need for quality evaluation is for following purposes
a) To get optimum quality at lowest price.
b) To decide whether cotton bought will can be processed to spin Yarn of
c) To check the quality of sample cotton with quality of delivered cotton.
d) To decide about correct machine settings and speeds for processing the
e) To estimate profitability of purchase decisions.
Knowing the cotton properties is only half the battle for profits. It needs
expertise to know how to get best of its value.
Currently popular instrument called HVI gives ready information on various
parameters to make correct purchase decisions.
If may not be possible to get all the desired qualities in one variety or
one lot of Cotton. In such case, an intelligent decision to select best
combination of different varieties or lots to get desired Yam quality is
necessary to get optimum yarn quality at optimum cost.
If correct evaluation is made, profits are large. Hence, evaluation of
quality is essential for optimum profit making and also make the customers
happy with supply of correct quality of Yarn.
Expert classers can manage to achieve reasonable level of correct
evaluation. Now, with availability of better instruments, it is better to
check qualities to make sure that desired quality of cotton is procured.
These details should give cotton buyer reasonable guidance to make correct
evaluation of cotton quality and ensure its suitability for producing
required quality of yarn.
||CHARACTERISTICS CO-RELATION TO
|1. Staple Length
|2. Fiber Strength
||Yarn strength, less Breakages
||Finer Spinning Potential
||Yarn Strength and even ness, better
|5. Non-Lint.content (Trash)
|6, Uniformity Ratio
||Better productivity and Evenness
||Less end Breakages
||Spinning problem by lapping & Dyeing
|11. Grey Value
|14. Moisture Content
||8.5% moisture content optimum for spinning at
QUALITY TESTING INSTRUMENTS:
||Fiber Bundle Strength
|HV I Instrument
||Length, Strength, Uniformity, Elongation,
Micronaire, Color and Trash
||Combined test of fineness &
|Shirley Trash Analyser
||Class & staple length
||Grey value & yellow ness.
|Polarised light Microscope or