Standard Practice for Use of the Tex System to Designate Linear Density of Fibers, Yarn Intermediates, and Yarns

SIGNIFICANCE AND USE
4.1 The tex system has been approved for general use by the International Organization for Standardization, Technical Committee 38 on Textiles (ISO/TC 38), which has also recommended a list of rounded tex numbers for use with fibers and all types of yarns. Conversion tables showing the rounded tex numbers corresponding to various numbers in different traditional systems are given in Tables D2260 and ISO 2947.  
4.2 The tex system for designation of the linear density of fibers and yarns is a direct system based on mass per unit length, M/L, and employs metric units of length and mass. The tex unit, grams per kilometre (1000 m) has been approved by ISO/TC 38 for use with all fibers and all types of yarn. The committee has also approved the use of kilotex and decatex numbers for coarse structures and decitex and millitex numbers for fibers.  
4.3 The tex system relates to the property commonly associated with coarseness, or inverse fineness of a yarn because the tex numbers increase with an increase in the size or mass per unit length of the yarn. The tex system is intended for use by all branches of the textile industry, in all countries, for yarns made from all types of fibers or mixtures of fibers.
SCOPE
1.1 This practice covers the use of the tex system to designate the linear density (number, or count) of fibers and of yarns made from any type of fiber or combination of fibers. It is also applicable to other textile materials, including yarn intermediates (slivers, rovings, tops, and so forth), single or plied yarns, cords, and threads.  
Note 1: The mass per unit length concept of linear density is applicable to any material which has a high ratio of length to cross section.  
1.2 Conversion factors for various indirect and direct yarn numbers to exact tex equivalents can be found in Standard Tables D2260.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

Status
Published
Publication Date
30-Jun-2018
Technical Committee
D13 - Textiles
Drafting Committee
D13.58 - Yarns and Fibers

Relations

Effective Date
01-Jul-2018
Effective Date
01-Jul-2018
Effective Date
01-Mar-2017
Effective Date
15-Sep-2015
Effective Date
01-Sep-2015
Effective Date
01-Apr-2015
Effective Date
01-Oct-2013
Effective Date
01-Oct-2013
Effective Date
01-Oct-2013
Effective Date
01-Oct-2013
Effective Date
15-Jun-2013
Effective Date
15-Jun-2013
Effective Date
15-May-2013
Effective Date
01-Feb-2012
Effective Date
01-Feb-2012

Overview

ASTM D861-07(2018), titled Standard Practice for Use of the Tex System to Designate Linear Density of Fibers, Yarn Intermediates, and Yarns, provides internationally recognized guidelines for measuring and expressing the linear density of textile materials using the tex system. Developed by ASTM International and aligned with ISO/TC 38 on Textiles, this standard ensures uniformity in specifying the mass per unit length of fibers, yarn intermediates, and yarns for both natural and man-made materials. The tex system has become the industry standard, supporting efficient communication and comparison across global textile supply chains.

Key Topics

  • Tex System for Linear Density: The tex system is a direct metric method for expressing linear density, defined as grams per kilometer (g/km). It allows for clear, direct comparison of fiber and yarn fineness and coarseness.
  • Applicability: This standard applies to all types of fibers, regardless of composition, and to yarn intermediates (such as slivers, rovings, and tops), single or plied yarns, cords, threads, and other textile materials with a high length-to-cross-section ratio.
  • Units and Multiples:
    • Standard unit: tex (g/km)
    • Submultiples: decitex (dtex), millitex (mtex)
    • Multiples: kilotex (ktex), decatex (dtex)
  • Reporting Recommendations: Linear density should be reported to three significant figures, with kilotex used for values over 999.9 tex.
  • Tenacity Expression: Breaking tenacity or elongation should be given in newtons per tex (N/tex) or its subunits, providing a standard way to assess fiber strength.

Applications

The tex system, as guided by ASTM D861-07(2018), is widely used in various sectors of the textile industry for standardized reporting and testing. Key applications include:

  • Quality Control and Specification: Manufacturers and suppliers use tex values to accurately describe and compare fiber or yarn products, supporting purchasing, quality assurance, and technical communication.
  • Research and Development: Laboratories and product developers apply these guidelines to assess new materials or blends, especially when evaluating properties like coarseness, fineness, or yarn composition.
  • Product Labeling and Compliance: Compliance with international standards like ASTM D861 ensures that products meet industry expectations and regulatory requirements for labeling and export.
  • Yarn Number Conversions: The standard provides for conversion tables (see ASTM D2260 and ISO 2947) to help transition between traditional and metric yarn numbering systems, easing international trade and collaboration.
  • Textile Product Engineering: The tex designation allows for precise engineering of products such as technical textiles, industrial threads, and specialty yarns, where uniform linear density is critical to performance.

Related Standards

  • ASTM D123 - Terminology Relating to Textiles: Provides definitions and terms used throughout textile standards.
  • ASTM D2260 - Tables of Conversion Factors and Equivalent Yarn Numbers: Offers conversion between traditional and metric yarn numbering systems.
  • ASTM D4849 - Terminology Related to Yarns and Fibers: Details specific terminology for fiber and yarn products.
  • ISO 2947 - Textiles-Integrated Conversion Table for Replacing Traditional Yarn Numbers by Rounded Values in the Tex System: International reference for converting and rounding tex system values.
  • WTO TBT Principles - Ensures the standard aligns with globally recognized approaches to standardization and technical barriers to trade.

By adhering to ASTM D861-07(2018), the textile industry benefits from a clear, uniform system for designating and comparing the linear density of fibers, yarn intermediates, and yarns, supporting international trade, innovation, and product quality.

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ASTM D861-07(2018) - Standard Practice for Use of the Tex System to Designate Linear Density of Fibers, Yarn Intermediates, and Yarns

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Frequently Asked Questions

ASTM D861-07(2018) is a standard published by ASTM International. Its full title is "Standard Practice for Use of the Tex System to Designate Linear Density of Fibers, Yarn Intermediates, and Yarns". This standard covers: SIGNIFICANCE AND USE 4.1 The tex system has been approved for general use by the International Organization for Standardization, Technical Committee 38 on Textiles (ISO/TC 38), which has also recommended a list of rounded tex numbers for use with fibers and all types of yarns. Conversion tables showing the rounded tex numbers corresponding to various numbers in different traditional systems are given in Tables D2260 and ISO 2947. 4.2 The tex system for designation of the linear density of fibers and yarns is a direct system based on mass per unit length, M/L, and employs metric units of length and mass. The tex unit, grams per kilometre (1000 m) has been approved by ISO/TC 38 for use with all fibers and all types of yarn. The committee has also approved the use of kilotex and decatex numbers for coarse structures and decitex and millitex numbers for fibers. 4.3 The tex system relates to the property commonly associated with coarseness, or inverse fineness of a yarn because the tex numbers increase with an increase in the size or mass per unit length of the yarn. The tex system is intended for use by all branches of the textile industry, in all countries, for yarns made from all types of fibers or mixtures of fibers. SCOPE 1.1 This practice covers the use of the tex system to designate the linear density (number, or count) of fibers and of yarns made from any type of fiber or combination of fibers. It is also applicable to other textile materials, including yarn intermediates (slivers, rovings, tops, and so forth), single or plied yarns, cords, and threads. Note 1: The mass per unit length concept of linear density is applicable to any material which has a high ratio of length to cross section. 1.2 Conversion factors for various indirect and direct yarn numbers to exact tex equivalents can be found in Standard Tables D2260. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

SIGNIFICANCE AND USE 4.1 The tex system has been approved for general use by the International Organization for Standardization, Technical Committee 38 on Textiles (ISO/TC 38), which has also recommended a list of rounded tex numbers for use with fibers and all types of yarns. Conversion tables showing the rounded tex numbers corresponding to various numbers in different traditional systems are given in Tables D2260 and ISO 2947. 4.2 The tex system for designation of the linear density of fibers and yarns is a direct system based on mass per unit length, M/L, and employs metric units of length and mass. The tex unit, grams per kilometre (1000 m) has been approved by ISO/TC 38 for use with all fibers and all types of yarn. The committee has also approved the use of kilotex and decatex numbers for coarse structures and decitex and millitex numbers for fibers. 4.3 The tex system relates to the property commonly associated with coarseness, or inverse fineness of a yarn because the tex numbers increase with an increase in the size or mass per unit length of the yarn. The tex system is intended for use by all branches of the textile industry, in all countries, for yarns made from all types of fibers or mixtures of fibers. SCOPE 1.1 This practice covers the use of the tex system to designate the linear density (number, or count) of fibers and of yarns made from any type of fiber or combination of fibers. It is also applicable to other textile materials, including yarn intermediates (slivers, rovings, tops, and so forth), single or plied yarns, cords, and threads. Note 1: The mass per unit length concept of linear density is applicable to any material which has a high ratio of length to cross section. 1.2 Conversion factors for various indirect and direct yarn numbers to exact tex equivalents can be found in Standard Tables D2260. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

ASTM D861-07(2018) is classified under the following ICS (International Classification for Standards) categories: 59.080.20 - Yarns. The ICS classification helps identify the subject area and facilitates finding related standards.

ASTM D861-07(2018) has the following relationships with other standards: It is inter standard links to ASTM D861-07(2013), ASTM D4849-13(2018), ASTM D123-17, ASTM D123-15b, ASTM D123-15a, ASTM D123-15, ASTM D4849-13e2, ASTM D4849-13, ASTM D4849-13e1, ASTM D4849-13e3, ASTM D123-13a, ASTM D123-13ae1, ASTM D123-13, ASTM D123-12e1, ASTM D123-12. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.

ASTM D861-07(2018) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.

Standards Content (Sample)


This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D861 − 07 (Reapproved 2018)
Standard Practice for
Use of the Tex System to Designate Linear Density of
Fibers, Yarn Intermediates, and Yarns
This standard is issued under the fixed designation D861; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2.2 ISO Standards:
ISO2947 Textiles—IntegratedConversionTableforReplac-
1.1 This practice covers the use of the tex system to
ing Traditional Yarn Numbers by Rounded Values in the
designate the linear density (number, or count) of fibers and of
Tex System
yarns made from any type of fiber or combination of fibers. It
is also applicable to other textile materials, including yarn
3. Terminology
intermediates (slivers, rovings, tops, and so forth), single or
plied yarns, cords, and threads. 3.1 For all terminology relating to D13.58, Yarns and
Fibers, refer to Terminology D4849.
NOTE 1—The mass per unit length concept of linear density is
3.1.1 The following terms are relevant to this standard:
applicabletoanymaterialwhichhasahighratiooflengthtocrosssection.
linear density, tex.
1.2 Conversion factors for various indirect and direct yarn
numbers to exact tex equivalents can be found in Standard 3.2 For all other terminology relating to textiles, see Termi-
nology D123.
Tables D2260.
1.3 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4.1 The tex system has been approved for general use by the
priate safety, health, and environmental practices and deter-
International Organization for Standardization, Technical
mine the applicability of regulatory limitations prior to use.
Committee 38 on Textiles (ISO/TC 38), which has also
1.4 This international standard was developed in accor-
recommended a list of rounded tex numbers for use with fibers
dance with internationally recognized principles on standard- and all types of yarns. Conversion tables showing the rounded
ization established in the Decision on Principles for the
tex numbers corresponding to various numbers in different
Development of International Standards, Guides and Recom- traditional systems are given in Tables D2260 and ISO 2947.
mendations issued by the World Trade Organization Technical
4.2 The tex system for designation of the linear density of
Barriers to Trade (TBT) Committee.
fibers and yarns is a direct system based on mass per unit
length, M/L, and employs metric units of length and mass. The
2. Referenced Documents
tex unit, grams per kilometre (1000 m) has been approved by
2.1 ASTM Standards: ISO/TC 38 for use with all fibers and all types of yarn. The
D123 Terminology Relating to Textiles committee has also approved the use of kilotex and decatex
D2260 Tables of Conversion Factors and Equivalent Yarn
numbersforcoarsestructuresanddecitexandmillitexnumbers
Numbers Measured in Various Numbering Systems for fibers.
D4849 Terminology Related to Yarns and Fibers
4.3 The tex system relates to the property commonly asso-
ciated with coarseness, or inverse fineness of a yarn be
...

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