What Is AB Yarn? Structural Characteristics and Solutions for AB Yarn Breakage
Sullivans International
•5 min read
AB yarn—more formally known as Sirospun yarn—is a composite spinning yarn widely used in modern textile manufacturing. By combining two rovings into a single yarn through a special spinning method, AB yarn delivers many of the benefits of ply yarn while maintaining the efficiency of single-yarn production.
In this guide, we’ll take a professional, production-oriented look at what AB yarn is, its structural characteristics, typical material combinations, and—critically—how to deal with AB yarn breakage during spinning.
AB yarn refers to a yarn spun from two separate rovings (A and B) that are drafted and twisted together into one finished yarn. Because two rovings are involved, it is commonly called AB yarn in China.
In international terminology, this process is known as Sirospun or Siro spinning, and the resulting yarn is called Sirospun yarn.
This technology was originally developed for wool spinning, but today it is widely applied in cotton spinning, polyester blends, and viscose blends.
AB yarn can also appear in color-differentiated forms, which are common in decorative and fashion textiles.
Siro spinning—also known as parallel twist spinning—follows this process:
👉 In simple terms: two rovings are spun into one yarn, creating a structure similar to ply yarn but produced in a single spinning operation.
Because both strands are twisted synchronously in the same direction, surface fibers are tightly bound:
AB yarn exhibits:
Compared with traditional ply yarn fabrics:
Compact siro spinning yarns can be used for:
Some of the most common AB yarn blends include:
TC / AB yarn Polyester + Cotton AB yarn Combines durability with natural comfort
TR / AB yarn Polyester + Viscose AB yarn Offers softness, drape, and dimensional stability
These blends are widely used in shirting, suiting, knitwear, and functional fabrics.
Because AB yarn consists of two separate drafted strands, a unique failure mode can occur:
This is one of the most critical quality risks in siro spinning.
To ensure stable quality, modern siro spinning lines are equipped with a single-yarn breakage protection device, which:
AB yarn (Sirospun yarn) bridges the gap between single yarn efficiency and ply yarn performance. It enables manufacturers to:
This is why AB yarn has become a strategic yarn solution in both traditional and high-end textile markets.
AB yarn is not just a yarn type—it’s a spinning philosophy. By intelligently combining two rovings into a single, compact structure, Sirospun yarn delivers strength, smoothness, and efficiency in one package.
When paired with proper breakage control systems and process optimization, AB yarn becomes a reliable, high-performance solution for woven and knitted fabrics alike.
For manufacturers aiming to replace ply yarn, reduce hairiness, or enhance fabric quality without increasing complexity, AB yarn remains one of the most effective spinning technologies available today.
This article provides a professional overview of AB yarn (Sirospun yarn), including structural characteristics, material blends, and industrial solutions for yarn breakage. For more insights into yarn technologies and textile manufacturing, explore our Yarn Insights series.