Spun polyester thread is made by spinning or twisting together shorter lengths of polyester fibers. This is similar to the way cotton threads are made. These are then twisted together to produce a thread of the desired size, like 20/2, 20/3, 30/2, 30/3, 40/2, 40/3, 50/2, 50/3, 60/2, 60/3 etc.
*Polyester is far and away the most popular thread for general sewing. It is a very strong economical thread. Polyester thread won't fade or shrink in the wash.
*The luster, or sheen, of polyester thread falls between that of cotton and rayon. A medium luster thread, it is suitable for almost any sewing project.
*Polyester threads do have some give or stretch to them.
*Polyester threads are available in a wide range of solid and variegated colors. The most popular thread size for sewing is 50wt, but many other weights are used depending on the project.