Cotton Plant
Cotton, natural vegetable fiber of great economic importance as a raw material for cloth. Its widespread use is largely due to the ease with which its fibers are spun into yarns. Cotton's strength, absorbency, and capacity to be washed and dyed also make it adaptable to a considerable variety of textile products.

Raw Cotton Testing
The word "cotton" as we know it today originates from the Arabic word "qutun". In Middle Dutch it was also known as "cotton" and with the development of Africans as a spoken language it became "catoen" and later "katoen".

Table Of Contents
1.0 Cotton Fiber
2.0 Cotton and yarn quality co-relation
3.0 Cotton Quality specification
3.1 Staple Length
3.2 Uniformity Ratio
3.3 Fiber strength
3.4 Micronaire for Fineness and Maturity
3.5 Cotton Grade
4.0 Influences
5.0 Fiber quality testing equipments

1.0 Cotton Fibre
There are a number of fiber properties, which can influence the quality of the yarn. A textile fiber is a peculiar object. Fiber properties vary very much within the lot. Optimal conditions can be obtained only through the mastery of the raw material. Therefore fiber testing is very important.

2.0 Cotton and Yarn Quality Co-Relation
Essential Characteristics of cotton quality and characteristics of Yarn quality of Yarn are given from detailed experimental investigations. Some of the important conclusions that 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 Yarn.

STRENGTH: Stronger fibers give stronger Yarns. Further, processing speeds can be higher so that higher productivity can be achieved with less end-breakages.

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 benefit.

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 raw material.

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 invisible loss. If moisture is less than 8.5%, then there will be tendency for brittleness of fiber resulting in frequent Yarn breakages.

FEEL: If the feel of the Cotton is smooth, it will be producing 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 Yarn defects to go higher. An analysis can be made of Yarn properties that can be directly attributed to cotton quality.

YARN COUNT: Higher Count of Yarn can be produced by longer, finer and stronger fibers.

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) at lowest.

TENSILE STRENGTH: This is directly related to fiber strength. Longer Length of fiber will also help to produce stronger yarns.

C.V. OF STRENGTH: is directly related CV of fiber strength.

ELONGATION: Yam elongation will be beneficial for weaving efficiently. Fiber with better elongation has positive co-relation with Yarn elongation.

C.V. OF ELONGATION: C.V. of Yarn Elongation can be low when C.V. of fiber elongation is also low.

MARS VARIATION: This property directly related to fiber maturity and fiber uniformity.

HAIRINESS: is due to faster processing speeds and high level of very short fibers,

DYEING QUALITY: will defend on Evenness of Yarn and marketing of cotton fibers.

BRIGHTNESS: Yarn will give brighter appearance if cotton grade is higher.

3.0 Cotton Quality Specifications

3.1 Staple Length
The most important fiber quality is Fiber Length
Staple (classification)
Length mm Length inches Spinning Count
Short Less than 24 15/16 -1 Coarse Below 20
Medium 24- 28 1.1/132-1.3/32 Medium Count 20s-34s
Long 28 -34 1.3/32 -1.3/8 Fine Count 34s - 60s
Extra Long 34- 40 1.3/8 -1.9/16 Superfine Count 80s - 140s

Notes:-

- Spinning Count does not depend on staple length only. It also depends on fineness and processing machinery.
- Length is measured by hand stapling or Fibro graph 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.

3.2 Uniformity Ratio
Length Uniformity is Calculated by 50SL x 100 / 2.5 SL
Significance of UR (Uniformity Ratio) is given below:
UR% Classification
50-55 Very Good 45-50 Good 40-45 Satisfactory
35-40 Poor Below 30 unusable

3.3 Fiber Strength
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 / Tex. 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

G/Tex Classification

Below 23 Weak
24-25 Medium
26-28 Average
29-30 Strong
Above 31 Very Strong

Strength is essential for stronger yarns and higher processing speeds.
- Fiber Fineness Fiber Fineness and maturity are tested in a conjunction using
Micronaire Instrument.
- 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.

3.4 Micronaire for Fineness and Maturity
Usually Micronaire value is referred to evaluate fineness of Cotton and its suitability for spinning particular count of Yarn.

3.5 Cotton Grade
Evaluating colours, leaf and ginning preparation determine Cotton grade. Higher-grade cottons provide better yarn appearance and reduced process waste.

4.0 Influences
Quality Evaluation Characteristics Co-Relation to Yarn

1. Staple Length Spinning Potential
2. Fiber Strength Yarn strength, less Breakages
3. Fineness Finer Spinning Potential
4. Maturity Yarn Strength and even ness, better dyeing
5. Non-Lint. Content (Trash) Reduced Waste
6. Uniformity Ratio Better productivity and Evenness
7. Elongation Less end Breakages
8. Friction Cohesiveness
9. Class Yarn Appearance
10.Stickiness Spinning problem by lapping & Dyeing quality
11. Grey Value Yarn luster
12. Yellowness Yarn Appearance
13.Neppiness Yarn Neppiness
14. Moisture Content 8.5% moisture content optimum for spinning at 65%

5.0 Fiber Quality Testing Equipments
Instrument Measurements

- Fibro graph Length
- Pressley Apertures Fiber Bundle Strength
- HV I Instrument
- Length, Strength, Uniformity, Colour,
- Elongation, Micronaire & Trash
- Stelometer Instrument Strength, Elongation
- Micronaire Combined test of fineness & maturity
- Shirley Trash Analyzer Trash Content
- Manual Test Class & staple length
- Moisture Meter Moisture
- Colorimeter Grey value & yellow ness. Brightness
- Polarized light Microscope or Casricaire test Maturity
- Photographic film Neppiness.