Key Yarn Characteristics

Industrial yarn specifications can include a wide range of physical and quality parameters. Understanding these values helps buyers compare yarns, review technical data and define suitable requirements for production.

The most relevant parameters depend on yarn type, fibre composition, spinning method and end application.

1. Yarn Count

Yarn count describes the fineness or linear density of a yarn. Different industries and regions use different count systems.

System	Abbreviation	Meaning	General Principle
Metric Count	Nm	Metres per gram	Higher Nm = finer yarn
English Cotton Count	Ne	Number of 840-yard hanks per pound	Higher Ne = finer yarn
Tex	tex	Grams per 1,000 metres	Higher tex = coarser yarn
Decitex	dtex	Grams per 10,000 metres	Higher dtex = coarser yarn
Denier	den	Grams per 9,000 metres	Higher denier = coarser yarn

Need to compare systems? Use our Yarn Count Converter.

2. Count Variation

Count CV%

Count coefficient of variation indicates how much measured yarn count varies around the nominal value.

Lower variation generally indicates better consistency, although acceptable limits depend on yarn type and application.

Mass Variation

Unevenness measurements assess short-term variation in yarn mass along its length.

More uniform yarn generally gives more consistent appearance and processing performance.

3. Twist

Twist Direction

Yarn twist direction is normally described as:

Z-twist
S-twist

Twist direction can be important where multiple yarns are combined or where the final textile process requires a particular construction.

Twists per Metre

Twist level may be expressed as twists per metre (TPM) or twists per inch (TPI).

Increasing twist can improve yarn cohesion and strength, but excessive twist may also affect softness, extensibility and fabric appearance.

4. Yarn Imperfections

Yarn testing may report imperfections such as thin places, thick places and neps.

Thin Places

Local sections where yarn mass falls below a defined percentage of its average value.

Thick Places

Local sections where yarn mass exceeds a defined percentage of its average value.

Neps

Short, highly concentrated mass faults which may affect yarn and fabric appearance.

Test thresholds are usually stated together with the result, for example −50%, +50% or +200%, depending on the test method.

5. Unevenness and Uster Testing

Yarn evenness is commonly assessed using specialised laboratory equipment. Reports may include values such as U%, CVm% and imperfection counts.

Lower unevenness values generally indicate more consistent yarn, but results should always be compared within the same fibre type, yarn count, spinning system and intended application.

6. Hairiness

Yarn hairiness describes fibres protruding from the yarn body. It can influence appearance, abrasion behaviour, lint generation, processing performance and fabric handle.

The preferred level depends strongly on yarn construction and intended use. A low hairiness value is not automatically better for every application.

7. Breaking Force

Breaking force is the force required to break a yarn specimen under defined test conditions. It is commonly expressed in centinewtons (cN).

Absolute breaking force should be considered together with yarn count, because a thicker yarn will normally withstand more force than a finer yarn.

8. Tenacity

Tenacity expresses breaking force relative to yarn linear density. This allows yarn strength to be compared more meaningfully across different yarn counts.

Typical units may include:

cN/tex
cN/dtex
g/denier

9. RKM

RKM, or breaking length, is another way of expressing yarn strength relative to its mass.

In practical terms, it represents the theoretical length of yarn that would break under its own weight.

Higher RKM values generally indicate higher yarn tenacity.

10. Elongation at Break

Elongation at break indicates how much a yarn stretches before breaking, expressed as a percentage of its original length.

Suitable elongation depends on fibre type, yarn construction, spinning method and intended processing conditions.

Other Parameters That May Matter

Moisture

Moisture regain and conditioning can influence yarn mass and some test results.

Fibre Composition

Blend ratio strongly influences strength, handle, dyeability and performance.

Colour

Shade consistency, fastness and dyeing method may be critical depending on the final textile.

Shrinkage

Dimensional change under heat, washing or processing may need to be specified.

Friction

Yarn-to-metal and yarn-to-yarn friction can affect processing efficiency.

Special Performance

Technical applications may require flame resistance, antistatic properties, UV resistance or other functions.

How to Read a Yarn Specification

A useful industrial yarn specification usually combines several parameters rather than relying on a single quality value.

Fibre composition
Yarn count
Spinning method
Twist
Strength or tenacity
Elongation
Evenness
Imperfection levels
Colour
Application-specific requirements

Important

There is no universal “best” yarn specification.

A value that is suitable for one application may be unsuitable for another. Yarn data should always be assessed in relation to the intended fabric, machinery and production process.