By Stacy McDougall
This is one of the most common questions we hear. The answer is simple, and difficult, at the same time.
The first thing to decide is what fiber to use. Rayon, polyester, cotton, silk, or metallic? All have their pros and cons, but basically it comes down to personal preference. I believe in using whatever threads work for your project. If it works well in your machine, and you like the effect you get while using it, then don't hesitate, enjoy it! Don't let the sewing "police" tell you what you should or should not use in your project. As odd as it sounds, sewing machines have preferences too. So experiment, and don't be afraid to use a particular thread just because it's not "made for that".
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.
100% cotton sewing thread is the traditional choice. Cotton is a natural thread that gives a soft, matte look.
Cotton thread is available in a wide range of weights, and is suitable for most sewing projects. 40wt and 50wt are the most common, but cotton threads range from 8wt to 100wt.
Cotton thread does not stretch a great deal, and will break if pulled too tightly. Cotton threads will fade with the sun, and shrink in the wash, so treat them as you would cotton fabrics.
Most cotton threads sold now are mercerized. This is a chemical and heat process that increases the luster of the thread. During the mercerizing process, fuzzy threads are burned off, creating a smoother surface. This smooth surface reflects light, increasing the luster of the thread. It also has the effect of increasing water absorbency, making the thread easier to dye.
Long staple cotton is finer and stronger than regular cotton. Most high quality threads are made with long staple cotton, creating a softer, stronger, higher luster thread. Long staple threads tend to have fewer slubs, lumps of lint spun into the cotton threads.
Silk is an elastic, though very strong, sewing thread, and is among the most beautiful of natural fibers. It has a high sheen, and creates a distinctive look when used in sewing projects. Silk threads are used in many high quality sewn garments.
Pure filament silk is the highest quality silk, as the fibers do not need to be spun; they come naturally in long strands from the silkworm.
Spun silks are made of shorter fibers. They come from broken cocoons or the beginning and end of cocoons.
Silk thread, and projects created with silk thread can be gently washed in the washing machine with a mild soap. Bleaching agents should not be used as they can damage the threads.
Rayon is a high sheen sewing thread, and often used as a lower cost alternative to silk threads. It performs well in high-speed sewing machines without breaking or fraying.
Most Rayon threads are available in 40wt, though 30wt can be found without effort. A wide range of colors and shades are available, including variegated colors.
Though some brands can be, rayon threads are not generally colorfast. It is best to avoid using any bleaching agents, including those made for colors.
Stitches sewn with Rayon threads create a very smooth consistent stitch, leading to a higher quality project.
Rayon threads do deteriorate over time, so attention should be paid to how it is stored. In low humidity regions, rayon threads can be stored in the refrigerator to extend thread life for a long as possible.
In most cases, when it comes to sewing thread, you get what you pay for. Good thread will stand up to high-speed machines without breaking or shredding. Bargain bin threads are inexpensive, but of poor quality, and will cost you in time and frustration.
Have fun, and don't be afraid to experiment with thread.
Stacy McDougall's company, Red Rock Threads sells quilting, sewing and embroidery thread online: http://www.redrockthreads.com.