Cotton Quality Specifications - Staple Length

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


  • Length is measured by hand stapling or Fibro graph for 2.5% Span Length.
  • 50% SL means at least 50% of total fibers have length exceeding this value.
  • 2.5%SL (Spun Length) means at least 2.5% of total fibers have length exceeding this value.
  • Spinning Count does not depend on staple length only. It also depends on fineness and processing machinery.


UR % Classification Grade
50-55 Very Good
45-50 Good
40-45 Satisfactory
35-40 Poor Below
30 Unusable

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.

  • Micronaire values vary from 2.6 to 7.5 in various varieties.
  • Finer Fibers give stronger yarns but amenable for more Neppiness of Yarn due to Lower maturity.
  • Fiber Fineness Fiber Fineness and maturity are tested in a conjunction using Micronaire Instrument.
  • Spinning Count does not depend on staple length only. It also depends on fineness and processing machinery.

Micronaire for Fineness and Maturity

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

Cotton Grade

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


S.No. 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%

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 & yellowness. Brightness
Polarized light Microscope or Casricaire test Maturity
Photographic film Neppiness

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