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 embroidery "police" tell you what you should or should not use in your project. As odd as it sounds, embroidery machines have preferences too. So experiment, and don't be afraid to use a particular thread just because it's not "made for that".
Rayon embroidery threads are currently the most popular threads used in embroidery machines. They perform consistently well in high-speed embroidery machines with very little breaking or fraying. Rayon is a high sheen thread, and often used as a lower cost alternative to silk threads.
Most Rayon embroidery 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 embroidery threads are not generally colorfast. It is best to avoid using any bleaching agents, including those made for colors.
Stitches sewn with rayon threads are very smooth and consistent, leading to a higher quality embroidery 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.
Polyester is rapidly catching up to the popularity of Rayon threads for embroidery. It is a very strong and economical thread. Polyester embroidery threads won't fade or shrink in the wash.
The luster, or sheen, of polyester thread falls between that of cotton and rayon.
Polyester threads do have some give or stretch to them.
Polyester embroidery threads are available in a wide range of solid and variegated colors. Like Rayon, the most popular thread size is 40wt, but 30wt and 50wt can be easily found.
Cotton embroidery thread is available in a wide range of weights, and is suitable for most embroidery 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 thread will fade with the sun, and shrink in the wash, so treat it 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 thread, and is among the most beautiful of natural fibers. It has a high sheen, and creates a distinctive look when used in embroidery projects.
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.
In most cases, when it comes to thread, you get what you pay for. Good embroidery thread will stand up to high-speed embroidery 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 polyester quilting, sewing and embroidery thread online: http://www.redrockthreads.com.