Sewing thread is usually less than 1/1000th of the weight of apparel, but it carries more one half the responsibilities for its performance.
Threads are used to form the stitches that hold the fabric parts together. They can be described by fiber type, constriction, and size. Threads can be made from a single fiber type such as cotton, linen, silk, rayon, nylon, polyester, or rubber or from a combination of fibers such as cotton/polyester.
Natural fiber threads:
The most common natural fiber used for threads, cotton threads. They have excellent sewabllity with little kinking or skip stitching. They are rarely affected by hot needles a common element of high-speed sewing machines and even sew well on poorly adjusted machines. Cotton threads dye well, and since they mold to the fabric better than other fibers, they are particularly attractive for topstitched elements.
Compared to synthetic threads, their strength and resistance to abrasion is inferior, and they shrink and mildew when wet. Cotton threads are produced with three finishes: soft, glace and mercerized. Soft finish threads receive no additional processing except bleaching and dyeing. Used on inexpensive garments, they are relatively inexpensive with good sewabllity but because they have a high shrinkage, seam pucker. This is frequently problem after washing. Glace' threads are treated with wax and special chemicals for a hard, glossy finish. They are stronger, more resistant to abrasion, and stiffer than other cotton threads. They are available in a limited color selection and used for gathering and for sewing heavy materials, leather, vinyl, and canvas. Mercerized threads are treated with a caustic solution to create a smooth, strong, lustrous thread. They are frequently used on cotton garments that will be dyed. Linen and silk threads are rarely used because of their high cost.
The most common synthetic threads, polyester and nylon, were developed to perform well on synthetic fabrics and withstand the chemicals and heat of durable press treatments. Compared to cotton threads of the same size, they are stronger, more resistant to abrasion, mildew and ultraviolet radiation, and have less shrinkage.
Combination fibers: One of the most common threads in use today is a combination of cotton and polyester, which combines the sew ability of cotton with polyester's strength and resistance to abrasion.
Thread construction: Although there are a variety of thread constructions, most threads used in garments are twisted, core spun, monofilament, or textured.
All natural fibers, with the exception of silk, begin with fibers - short lengths of staple, which are twisted together to make a single-ply thread. Then two or more plies are twisted together in the reverse direction to make a sewing thread with a balanced twist. Without this balance, the thread could not be controlled. Most threads are finished with a "Z" or left twist because the action of the lockstitch machine would cause threads with an "8" twist to unwind One exception is the double-needle lockstitch, which has two bobbins one revolving to the left and one to the right. This type of machine requires threads with both twists. In addition to the natural fibers, polyester, silk, and nylon filaments cut or broken Into staple lengths. Spun polyester thread is the most common.
Core spun threads begin with a continuous filament of polyester, which is then wrapped with a cotton or polyester sheath to make a single-ply thread. Then the two to four plies are twisted together to make the sewing thread Cotton/poly threads have the advantage of better sew ability, while poly/ poly Threads can be dyed in a one-step process.
Monofilament is simply a single filament of nylon of polyester. It is stiff, wiry, and unravels easily. It is uncomfortable next to the skin and harsh on machines. Available only in clear, light and dark gray, monofilament Threads are translucent and reflect the fabric's color. Monofilament threads are used primarily for blind hemming and surging inexpensive garments and Household textiles.
Made of multifilament that have been crimp textured or bulked by twisting, crimping and untwisting, textured threads have a soft Land, good coverage and elasticity. The most common use of textured threads is in the loopers of over edge and cover stitch machines; however, very fine sizes can be used as needle threads on chain stitch and over edge machines. They can also be used as bobbin threads to ass moderate stretch to a lock stitched seam.
The thread size is dependent on many factors-such as the fabric weight and type, stitch and seam type, machine speed, needle size, end use, and seam strength. Most threads are sized using Tex system or the cotton count system.
Factors in thread Selection:
1. Garment design, type, quality, end use, and life expectancy.
2. Desired strength and durability.
3. Fabric weight and type.
4. Stitch and seam type, number of stitches/inch, machine speed, and needle size.
This article was originally published in the February issue of the magazine, 'New Cloth Market: The complete textile magazine from textile technologists.'