A yarn is a flexible strand of textile fibers or filaments, suitable for making fabric. It can have twist or be untwisted.1 This introduction separates four parts of a yarn description: fiber form, yarn construction, twist, and fineness.
From fibers to fabric
Yarn connects fibers with fabric-making processes. Weaving interlaces yarns; knitting arranges them into connected loops. This fiber-to-yarn-to-fabric sequence applies to woven and knitted textiles, but it is not a rule for every fabric: nonwoven production can start from fibers without first making yarn.2
Spun and filament yarns
Spun yarn is made from staple fibers—fibers with a limited length. Filament yarn contains fibers that extend essentially along the yarn’s whole length.3
- Monofilament yarn: one continuous filament.
- Multifilament yarn: many continuous filaments together.3
These terms describe fiber form within the yarn. They answer a different question from whether the yarn is single or plied.
Single and plied yarns
A single yarn, also called a singles yarn, is one yarn strand before plying. It can be spun, monofilament, or multifilament. A plied yarn joins two or more single yarns by twisting them together.34
Consequently, “single” does not mean “one filament.” A multifilament yarn can be a single yarn. Keep the number of filaments within a yarn separate from the number of yarn strands combined by plying.3
Twist: direction and amount
Twist gives fibers a spiral arrangement around the yarn. In spun yarns it commonly helps hold the staple fibers together. The amount of twist is expressed as turns per unit length, such as turns per meter or turns per inch.45
To identify the direction, hold the yarn vertically and compare the slant of its fibers with the middle stroke of a capital letter:
- S twist: the slant runs from upper left to lower right.
- Z twist: the slant runs from lower left to upper right.4
S and Z describe direction, not how many turns are present. Twist is not a universal requirement: the general definition of yarn also includes untwisted forms.14
Count and linear density
Yarn count describes fineness using the relationship between mass and length. Linear density means mass per unit length. Direct count systems express this relationship; indirect systems express length per unit mass.6
Within a direct system, a larger number means more mass for the same length. Within an indirect system, a larger number means more length for the same mass. Identify the system or unit before interpreting a count.6
Count is not a diameter measurement: fiber packing can change diameter even at the same linear density. It is also different from ply count. A single yarn and a plied yarn can have the same effective count, so the number of plies alone does not establish fineness.64
Citations
-
- Fundamentals of Yarn Technology — Australian Wool Education Trust / University of New England (Woolwise) · WOOL482/582 Wool Processing, Topic 8 (2012) · 2012. Evidence locator: Introduction, printed p. 8-1.
-
- Fabric Manufacture I — 1. Introduction to Fabric Manufacturing; 1.1 Introduction — NPTEL / Indian Institute of Technology Delhi. Evidence locator: Fabric Manufacturing Technologies; Weaving Technology, opening paragraph.
-
- Fundamentals of Yarn Technology — Australian Wool Education Trust / University of New England (Woolwise) · WOOL482/582 Wool Processing, Topic 8 (2012) · 2012. Evidence locator: section 8.1 Yarn types and structures, printed p. 8-2.
-
- Yarn Spinning — Cotton Incorporated / CottonWorks. Evidence locator: Yarn Twist; Terms to Know: S-Twist, Z-Twist, Turns Per Inch (TPI), Ply Yarn.
-
- Fundamentals of Yarn Technology — Australian Wool Education Trust / University of New England (Woolwise) · WOOL482/582 Wool Processing, Topic 8 (2012) · 2012. Evidence locator: section 8.3 Yarn twist, opening and Real twist, printed p. 8-7.
-
- Fabric Manufacture I — 1. Introduction to Fabric Manufacturing; 1.1 Introduction — NPTEL / Indian Institute of Technology Delhi. Evidence locator: Some Basic Definitions Related to Woven Fabrics: Yarn count; Packing factor or packing coefficient.