Silk Thread

Definition and Material

Silk thread is a thread made from natural fiber using silk obtained from silkworm cocoons. Because the fiber surface is relatively smooth, it has a distinctive luster that softly reflects light and a supple texture. It is used not only for apparel but also for embroidery and kimono-related applications.

Even when made from the same silk material, filament yarn made from long fibers and spun yarn made by spinning short fibers differ in appearance and hand feel. In general, filament yarn is more likely to have luster and smoothness, while spun yarn has a more subdued appearance.

Twist and Thread Structure

Silk thread is made in structures such as single yarn, which uses one thread, and plied yarn such as double yarn and multiple yarn, which twist multiple single yarns together. Twist affects thread strength, surface appearance, and ease of sewing; thread with more twist generally has a firmer appearance, while thread with less twist makes it easier to bring out a soft luster.

When used as sewing thread, the required thickness, twist, and luster are selected according to whether it will be visible as stitching on the surface of the garment or used for joining inside the seam allowance. In machine sewing, not only the thread structure but also compatibility with the needle and sewing speed affect the finish.

How Thickness Is Expressed

The thickness of silk thread may be shown by yarn count or nominal count. Yarn count is a unit that indicates thread thickness, but the meaning of the number differs depending on the notation system used. For this reason, a number alone cannot be simply compared with other types of thread or thread expressed by a different system.

Nominal count may be used as a thickness category set for each product. Even with the same nominal count, thickness and strength may differ depending on the thread structure, number of twists, and manufacturer specifications. Before ordering or mass production, check the notation unit, thread sample, and actual sewing sample together.

• Check the count notation system and the structure, such as single yarn or double yarn.
• If you do not want the stitches to stand out, choose a thickness and color that blend with the textile.
• When using stitches as a design feature, confirm the thickness and the appearance of the luster with a test sew.

Main Applications

Silk thread is used for sewing silk textiles, hand sewing, button attaching, and embroidery. It is especially chosen for formal wear, dresses, blouses, kimono items, and fashion accessories where luster and delicate texture are emphasized, in order to match the texture of the outer fabric.

However, caution is needed when the application site is subject to strong friction or heavy loads. Depending on the material, construction, thickness, and wearing conditions of the textile, strength and durability should be considered, including sewing threads other than silk thread.

Selection and Sewing Precautions

When selecting, check not only the color tone, luster, and thickness relative to the outer fabric, but also the strength required for the seam and the washing or cleaning conditions. Since silk is a natural material, it may be affected by friction, sweat, chemicals, and sunlight, so pre-testing in line with the intended use of the product is important.

In machine sewing, adjust the needle size, needle point shape, upper and lower thread tension, and sewing speed to prevent thread breakage, skipped stitches, and puckering. On thin or delicate silk textiles, seam puckering is more noticeable, so test sewing should be done with offcuts.

Silk thread differs from synthetic fiber threads such as polyester thread in luster, moisture absorption, weather resistance, and response to heat. Also, some embroidery threads are intended mainly for decoration, and their required strength and processing differ from machine sewing thread used for joining, so they should be selected according to their application.

Frequently Asked Questions

Must silk thread always be used when sewing silk textiles?

Not necessarily. It is effective when you want the luster and texture to match the outer fabric, but seam strength, usage environment, and washing or cleaning conditions must also be considered. In particular, for high-stress areas, decide on the appropriate thread after test sewing and product testing.

Is a higher yarn count number finer for silk thread?

Because the meaning of yarn count differs depending on the notation system, the thickness cannot always be judged by the size of the number alone. Nominal count may also be used as a product category. When comparing, check whether the notation system is the same, and confirm the actual thickness with a thread sample, specifications, and test sewing.

What should be noted when machine sewing with silk thread?

If the needle, thread tension, and sewing speed are not matched, thread breakage or seam puckering may occur. Adjust the needle and tension according to the fabric thickness and woven or knit structure, and perform test sewing using the same fabric before mass production. It is also important to avoid direct sunlight and high temperature and humidity during storage.