Rayon thread is one of the most common types of thread used for embroidery machines. There are several advantages to using this type of thread, including that it tends to perform well in high-speed machines without fraying or breaking. This type of thread has a high sheen to it, so serving as a cost-effective alternative to silk is one of its more common uses. It is available in a wide range of colors, though color availability varies based on manufacturer.
Rayon threads are available in different weight classes, but the most popular weight classes are called 40 weight and 30 weight. In thread theory, 20-30 weight is ideal for decorative stitches, 40 weight is best for quilting and 50 weight is recommended for piecing, bobbin use and appliqué work. When experimenting with rayon, it is important for crafters to find what works for them rather than to follow set standards. Information on the weight and ply of the thread is available on the end of the thread spool. These numbers are generally expressed as weight/ply.
Most spools of rayon thread have a label on one end containing essential information. This information should include the manufacturer, the color code, the weight and ply, fiber content and whether the thread is mercerized. Mercerization is a treatment involving sodium hydroxide that increases the thread's luster and its ability to absorb dye. Higher thread numbers denote finer threads, and ply numbers indicate how many individual strands are twisted together. A 60-weight thread with three strands twisted together will read as "60/3" on the label.
Rayon thread is commercially available in a wide range of different colors. Stitches sewn or embroidered using rayon are smooth and consistent, lending to a higher-quality project. Some are colorfast, but in general, rayon thread colors can fade over time. When one is washing projects sewn using rayon thread, only bleach-free products should be used, to prevent the colors from fading prematurely.
This type of thread can deteriorate over time, especially when stored improperly. In regions with low humidity, the best place to store rayon thread is in a refrigerated environment. Otherwise, it is best to store the thread in a closed storage case in a cool, dry place. This will help to extend the life of the thread. Excessive exposure to moistness, heat and sunlight can quicken the deterioration process.