ISO 2:1973

Overview

ISO 2:1973 is an international standard established by the International Organization for Standardization (ISO) that defines the designation of the direction of twist in textile yarns and related products. This standard applies to various yarn intermediates such as slivers, slubbings, and rovings, as well as to single yarns, plied yarns, cabled yarns, threads, twine, cordage, and rope. The core purpose of ISO 2:1973 is to provide a clear and universally accepted method of indicating whether the twist in these products runs in the S or Z direction.

Key Topics

• Direction of Twist Designation
  The standard specifies using the capital letters S and Z to indicate the direction of yarn twist:

  • S twist: The twist spirals in the same direction as the central portion of the letter "S". When held vertically, the fibers or filaments slant in this same direction.
  • Z twist: The twist follows the inclination resembling the central portion of the letter "Z", with the spiral slanting accordingly when held vertically.

• Yarn Types Covered
  ISO 2:1973 applies to a wide range of yarn types, including:

  • Yarn intermediates such as slivers, slubbings, and rovings
  • Single yarns
  • Plied yarns and cabled yarns
  • Threads, twine, cordage, and rope

• Designation for Complex Yarns
  For complex yarns made by twisting two or more individual yarns together (e.g., plied or cabled yarns), the last inserted twist's direction is designated by the letters S or Z.

• Additional Notation
  In specific situations, lowercase letters "s" and "z" may be used, for example, to indicate the direction of winding or lay when a yarn is wrapped around a core like a wire.

Applications

The ISO 2:1973 standard is crucial for textile manufacturers, quality control laboratories, and product designers to ensure consistent communication and product specifications related to yarn twisting. Practical applications include:

• Manufacturing: Standardizing twist direction in production processes to achieve desired yarn qualities such as strength, elasticity, and appearance.
• Quality Assurance: Verifying yarn twist direction during inspections and testing, ensuring conformity with product standards.
• Product Design: Selecting appropriate yarn twist directions to influence the final textile product’s performance and aesthetics, including fabric hand and durability.
• Supply Chain Communication: Facilitating clear interchange of yarn specifications between suppliers, manufacturers, and customers globally.

Related Standards

While ISO 2:1973 specifically deals with the designation of twist direction in yarns and related products, it complements other textile standards under ISO Technical Committee 38 (Textiles), which cover:

• Yarn strength and testing methods
• Textile fibers identification
• Fabric construction and performance standards
• Terminology related to textile materials and processes

For professionals working with textile production, referencing ISO 2:1973 alongside these related standards ensures comprehensive quality and specification control.

Keywords: ISO 2, yarn twist direction, S twist, Z twist, textile yarns, plied yarns, cabled yarns, yarn twist designation, textile standards, ISO textile standards, yarn intermediates