Twist Coefficient

Definition and Overview

The twist coefficient is an index that indicates the degree of twist applied to a yarn while taking yarn thickness into account. Since twist count alone does not make it easy to compare thick and fine yarns fairly, it is used together with yarn count or linear density to determine the relative twist strength of yarns.

The calculation formula and unit vary depending on the way values are expressed, such as cotton count, wool count, or denier, as well as trade customs. For this reason, it is important to compare twist coefficient values only between yarns of the same count system and under the same calculation conditions.

Effects on Hand and Performance

In general, yarns with a higher twist coefficient have tighter fibers, a cleaner surface, and are more likely to produce firmness, body, and a crisp feel. They may help reduce fuzz and can contribute to strength and abrasion resistance, although results vary depending on the material and spinning method.

On the other hand, yarns with a lower twist coefficient tend to trap more air between fibers and are more likely to provide loft and softness. However, fuzz and pilling may become more noticeable, and care may be needed to prevent yarn breakage and loss of shape.

For strongly twisted yarns, the finished woven or knitted fabric may show fine surface texture, a cool feel, and good drape. On the other hand, the torque of the yarn, that is, the force that makes the twist try to return, can cause skewing or twisting.

Main Applications

The twist coefficient is used in the design of a wide range of fabrics where the hand of the yarn affects product characteristics, such as shirting, blouse fabrics, suit fabrics, knit fabrics, and towel fabrics. It is especially important in materials for spring and summer that are intended to feel smooth against the skin and dry to the touch.

For autumn and winter knits, underwear, towels, and other products that emphasize softness and loft, designs that do not use excessive twist are also considered. However, applications are not determined by the twist coefficient alone; they are evaluated together with the raw material, yarn structure, weave or knit construction, density, and finishing.

Selection and Handling Notes

When selecting fabric, check not only the twist coefficient value but also the count, whether it is single yarn or plied yarn, twist direction, construction, and hand after finishing using a sample. It is important not to simply compare values from different calculation methods, but to confirm them as design conditions within the same material and specification.

For fabrics made with high-twist yarns, before cutting, unwind the fabric to check for twisting and shrinkage, then align the grain before cutting. In sewing, test the needle, thread, and feed settings that suit the fabric in advance to prevent puckering and seam slippage.

Changes in shrinkage and appearance caused by washing are also affected by fiber type, dyeing and finishing, and construction. Before mass production, perform a water-immersion test or washing test to check finished dimensions, skew, wrinkles, and changes in hand, and reflect the results in the pattern and specifications.

Differences from Similar Terms

Twist refers to the operation or state of twisting fibers or yarn into a spiral shape. The twist coefficient is a numerical index that expresses the degree of that twist in relation to yarn thickness. Compared with showing only the twist count, it makes it easier to compare yarns of different thicknesses.

High-twist yarn is a term for yarn that has been given more twist than ordinary yarn. The twist coefficient is also used to judge and manage whether yarn is high twist, but the term high-twist yarn itself does not indicate a specific formula or a fixed numerical range.

Frequently Asked Questions