Natural fibers come from plants and animals and are either spun or twisted into yarns. We are most familiar with cotton and wool, but other common thread products are made from silk, hemp, jute and linen (also known as flaxen cord).
Synthetic fibers are made from various chemicals or a combination of chemicals and natural products. Rayon is created from cellulose acetate and other chemicals. It is forced through small holes to form individual fibers. Other synthetic fibers are polyester, acrylic and nylon. In most cases, a synthetic fiber has greater strength than a natural fiber because of advanced science and techniques.
All fibers are formed into threads from either staple or continuous filaments. 'Staple' refers to natural fibers in various lengths and synthetic fibers cut to a predetermined length in the manufacturing process. The term "long staple" usually refers to a smoother, stronger thread. Short staple thread usually has a fuzzy appearance and has less strength. While extra-long staple is the currently the highest-quality staple when it comes to natural fibers. Continuous filament refers to synthetic fibers of indefinite length.
Thread size measurement
There are three primary ways thread is measured.
1. Weight. The smaller the number, the heavier the thread. Common thread weights are 30 wt., 40 wt., and 50 wt.
2. Denier. Weight (in grams) of 9000 meters of thread. A larger number indicates heavier thread. A number such as 120/2 equals two strands of 120 denier thread for a total of 240 denier. Most embroidery thread has a denier measurement. However, this measurement traditionally applies only to synthetic threads. Comparative note: A 40 wt. thread approximately equals 240 denier.
3. Tex. Weight (in grams) of 1000 meters of thread. 40 wt. = 240 denier = tex 25.