Classing/grading of cotton

Cotton is cultivated in the world in a large area, and its production is about 25000 million tons per year. Since cotton is cultivated in different environmental conditions hence its quality varies from area to area and country to country, field to field, variety to variety, plant to plant, and ball to ball. But in industry, we want cotton of uniform quality and also fixing the price depending upon the quality, hence need commercial cotton as classing/grading of cotton.

The expert of cotton is called a classer. The assessment of quality by the classer is called the grading of cotton.

Classing/grading of cotton depends upon the following characteristics.

Appearance of cotton

Classing/grading of Cotton is compared with a standard tuft of cotton in respect of its colour, brightness, stains, spots, and foreign matter (dust, motes, leaves, stems, etc.). if the cotton has fewer impurities and a good appearance then it is of the best quality.

The ginning of cotton is checked, if it is saw ginned it is lustrous as compared to roller ginned cotton. So saw ginned cotton graded as the best quality.

Also picking is checked if it is mechanical picking grading is less due to stains and spots in it.

Waste content of cotton

The grade of cotton is good in its waste content. The manufacturing waste in the blow room and carding, waste depends upon of grade of cotton. If total waste is more than 20~25%then the cotton is not useable the acceptable waste of cotton is  6~12 %, and good cotton has waste contents that should not be more than 6%.

What is the Staple length of cotton?

Classing/grading of cotton
Classer length

The staple length of cotton fibre is the most important property indicating its performance.

The accurate staple length of cotton is not measured, the best is to measure the tuft length of cotton. cotton classer takes a cotton sample about once and pull out it into two parts between the thumb and first fingers of two hands. the part of one hand is dropped and pulled out fibre tuft from another hand to make the ribbon of cotton. the ribbon is stroked between the thumb and index figures into a uniform tuft and either measured its length or more usually judged. This is called the staple length of cotton.

Characteristics of cotton

Minor qualities of cotton which are not measured by experts, but are taken in laboratories are called characteristics. The characteristic of cotton are

1-Fineness of cotton fibre

The weight of 1″ of fibre is called its fineness, also less weight of 1″ fibre is called fine fibre and vice versa. The conclusion is the greater the count finer the will be yarn.

Fibre fineness Microgram/ inch


blow 3 very fine
3~3.9 fine
4~4.9 average
5~5.9 course
above 6 very coarse


2-Strength of cotton fibre

The important priority is the strength of the fibre. The strength depends upon the maturity of cotton fibre. mature cotton is one in which the secondary wall full grew. Additionally, the Presley strength tester is used for the measurement of the strength of a bundle fibre

Strength = 1000 ponds/inche2 Grade
89~97 strong
81~88 average
72~80 fair
71~blow weak

Universal grading/classing standard of cotton

The united state department of agriculture (U.S.D.A) has mentioned universal grades of cotton. But these grades are only for saw-ginned upland cotton accepted in the world.

  1. Midding fair (M.F.)
  2. strict good middling (S.G.M.)
  3. Good middling (G.M.)
  4. Strict middling (S.M.)
  5. Middling (M)
  6. strict low middling (S.L.M.)
  7. Low middling (L.M.)
  8. Strict good ordinary (S.G.O.)
  9. good ordinary (G.O.)

These 9 grades are universal grades. for grading, there is a universal grading/classing box. Grade number 5 is the basis for grading.


Acceptance of U.S.D.A

Although these grades are accepted in the world, many countries do not accept them due to the following reasons.

  1. These are only for saw-ginned cotton countries while roller-ginning-producing cotton can’t accept these standards.
  2. These standards are for American upland cotton which is creamy but can’t accept in other saw ginned like Pakistan and India where cotton colour is more white and Egyptian cotton is more creamy. So these colour grades cant fulfil the physical colour range.
  3. Thirdly these grades are not applicable for long-staple cotton i-e Egyptian cotton.
  4. Lastly, there is no consideration of maturity and strength in these grades.

In conclusion, the cotton standard can’t is used throughout the world as every country has its own standard.

  1. In the United States U.S.D.A (united state department of agriculture)
  2. In Pakistan K.C.A (Karachi cotton association)
  3. In Idia CAI (cotton association of India)
  4. In Egypt C.E.A (Cotton Egypt Association)
  5. In China C.C.A (China Cotton Association)

So we can say every country has its own commercial standard.

Some standards for saw ginned cotton short staple

Following standards are followed to some extent

Grades  On/OFF
Super choice 3 grade ON
Choice 2 grades ON
Super fine 1 grade ON
Fine Pass grades
Fully good 1 grade OFF
Good 2 grades OFF
Fair OFF

In practice, physical grade boxes are prepared for each set of cotton with 4F, and LF with saw-ginned cotton.

Some standards for saw-ginned and roller-ginned cotton long staple

Below table for both saw and roller ginned cotton in long staple.

Roller ginned cotton standards for long staple
Grades ON/OFF
Superfine 1 grade ON
Fine~super fine 1/2 grade ON
Fine Pass
Fully good~fine 1/2 grade OFF


Saw ginned cotton standards for long staple
Grades ON/OFF
Superfine 1 grade ON
Fine Pass Grade
Fully good~fine 1/2 grade OFF

Instruments used for classing/grading cotton


Classing/Grading of cotton

High volume instrument measures (HVI) trash or non-lint content by using cameras, made by Uster Technologies. The increasing number of fibre measurement trends is provided to a set of instruments that can be analysed on the computer and can print results. HVI measure the most important fibre classing/grading properties that are high throughput results in spinning mills.

The trash is measured by using a video camera while micro-nair is measured by using air flow through the sample and the remaining parameter is measured by Fibrograph. The system is capable of measuring 180 samples per hour.

The following characteristics can be measured by using an HVI instrument.

HVI spectrum measurement
i Spinning consistency index SCI
ii Micro-naire Mic
iii Maturity index Mat
iv Upper half mean length Len
v Uniformity index Unf
vi Short fibre index SFI
vii Strength Str
viii Elongation Elg
ix Moisture Moist
x Reflectance Rd
xi Yellowness +b
xii Colour grade CG
xiii Trash count Tr Cnt
xiv Trash area Tr Area
xv Trash grade Tr Grade
xvi Fluorescence UV
xvii Neps Nep



Classing/Grading of cotton

Advanced fibre information system is used to measure specially neps in cotton. There are modules one are measuring the number of neps and the second one is used to measure the length and fibre diameter. This device work on Aero-mechanical principles.

The following characteristic of fibre can be tested by using this instrument.

AFIS measurement
i Fibre length L(w) & its CV%
ii Upper quartile length UQL(w)
iii Length(by number) L(n) & its CV%
iv Short fibre content SFC(n)
v Short fibre content SFC(w) <0.5%
vi Fibre length 2.5% UQL 2.5%
vii Fibre length 5%  UQL 5%
viii Fineness m-tex F mtex
ix Immature fibre content IFC%
x Maturity ratio Mat ratio
xi Neps (diameter) Nep(um)
xii Neps (number) Ct/gram
xiii Seed coat neps(diameter) SCN(um)
xiv Total neps Cnt/gram
xv Nep mean size Mean size
xvi Dust Dust Cnt/gram
xvii Trash Trash Cnt/gram
xviii VMF% VMF%


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