Core-spun Thread
Core-spun thread is a sewing thread made by spinning short fibers around a strength-bearing filament core, making it easy to achieve both strength and a texture suited to the material.
Definition and Overview
Core-spun thread is a thread with a core-sheath structure at its center. In general, a filament, which is a continuous long fiber, is used as the core, and short fibers are spun around it. It makes it possible to take advantage of the core’s strength while giving the surface the look and feel of the wrapped fibers.
“buttonhole thread” may also refer to the thread placed at the center itself, and is not necessarily synonymous with core-spun thread as a whole. Core-spun thread is used as a name for a structure and manufacturing method that combines fibers serving as the core and sheath.
Materials and Twist / Structure
A typical combination uses polyester filament for the core and cotton short fibers for the sheath. In this case, the polyester core supplements tensile strength, and the cotton-covered surface contributes to an appearance and feel that blend well with cotton materials. The sheath material may also be something other than cotton.
After spinning, the thread may be twisted further, and if necessary, multiple threads may be twisted together. The twist direction, amount of twist, and whether it is single yarn or ply yarn affect fuzz, luster, strength, seam appearance, and sewability, so confirmation according to the application is necessary.
How Thickness Is Expressed
The thickness of core-spun thread is indicated by thread count or nominal thread count. Thread count is a unit that expresses thread thickness, but the meaning of the number differs depending on the system used. In general, some systems use larger numbers for finer thread, but the numbers alone cannot be compared without checking the notation method.
For sewing thread, a manufacturer-specific nominal thread count may also be used. Nominal thread count is convenient as a practical thickness category, but threads that differ in material, structure, twist, or standard are not necessarily the same thickness. Specifications list the thread type, material, and thread count or nominal thread count together.
- Thin thread is used for sewing lightweight fabrics and delicate seams.
- Thick thread is used for heavyweight fabrics, load-bearing areas, and decorative stitching.
- Suitability should be checked in combination with the textile, needle, and seam type.
Main Applications
Core-spun thread is used for sewing where both strength and surface compatibility are desired, such as shirts, pants, casual wear, and uniforms. When sewing cotton or cotton-blend materials, there is an approach of matching the sheath material on the surface to the appearance of the fabric.
It is used not only for lockstitch seams but also for stitching. However, when the thread is intended to be visible as stitching, color, thickness, fuzz, and luster affect the finished look. Before mass production, it is important to make sewing samples using the actual fabric and sewing conditions.
How to Choose and Sewing Precautions
When selecting it, confirm the fabric material, thickness, elasticity, the load on the seam, whether washing or garment washing is involved, and the desired seam appearance. Thread that is extremely thick relative to the fabric can lead to puckering and stiffness in the seam, while thread that is too thin may result in insufficient seam strength.
In sewing, adjust the thickness of the sewing machine needle suitable for the thread, the needle eye, upper and lower thread tension, and sewing speed. Check in advance for fuzzing or abrasion that could expose the filament in the core, as well as seam shrinkage, thread breakage, and skipped stitches. For stretch fabric, also evaluate how well it follows stretching.
Frequently Asked Questions
What is the difference between core-spun thread and polyester spun thread?
Core-spun thread is generally a thread with a structure in which a filament serves as the core and is covered with short fibers. Polyester spun thread, on the other hand, refers to thread spun from polyester short fibers. The former can more easily provide strength through the core, while the latter has the texture of spun thread throughout.
Can core-spun thread be used for stretch fabric?
Yes, but it is necessary to confirm whether the thread and seam can follow the fabric’s stretch sufficiently. For fabrics with high elasticity, consider the seam specification as well as thread with elasticity. Before full production, test for thread breakage and seam waviness during extension and recovery.
Can another core-spun thread be substituted if the nominal thread count is the same?
Even if the nominal thread count is the same, the core and sheath materials, twist, actual thickness, strength, fuzz, and finish may differ. When substituting, review the sewing conditions including the needle and tension, and confirm seam strength, appearance, and post-wash condition through trial production.
