Silk yarn is an expensive commodity when compared with other natural yarns. Knowing how to choose the best silk yarn is a good way to ensure your money is well-spent. There are two basic types of silk yarn: reeled yarn or plied yarn.
All yarns are made from spinning fibers together, and silk is made from the unraveled fibers of a silkworm cocoon. The silkworm combines fibroin proteins and a gummy protein called sericin to spin its cocoon. To produce a finished product, the sericin must be removed from the silk with soap and water. If this gummy substance is not removed completely, an unpleasant fishy smell will remain. This is why it is important to choose silk yarn in person and smell it, rather than purchasing by mail order.
Silk can be made into woven fabrics or hand dyed yarn for knitted garments. Because the silk is dyed by hand, it is important to choose yarn that is from the same dye lot. Be sure to buy more than enough for your knitting or other yarn projects.
Reeled silk yarn comes in varying counts to identify its thickness. It is made with only the long silk fibers, making it less likely to pill. The unbroken strand creates the best sheen for silk as well. Reeled yarn can be twisted to minimize the chance of pulling which occurs when silk catches on burrs.
One meter of yarn that weighs 1 gram will be labeled #1 yarn, which is the thickest standard silk yarn. The thinnest yarn is #20. Since yarn is sold by the 1-gram ball, a higher number means a longer and thinner yarn.
Another pair of numbers shows the size of plied yarns, where several strands of reeled yarn are twisted together. The count and the number of strands in the ply are used to identify such yarn. A 10/3 yarn is made with three strands of medium thickness silk.
The quality of the silk yarn depends on the length of the fiber used in spinning. Top quality is made of the unwound threads of the silkworm cocoon. Lower quality silk yarn, called noil, is made from the crushed pupa left after making top quality yarn. This yarn will have less luster and a stronger odor since the sericin cannot be washed out of the pulp. The smell can be washed away, but it will return if the garment becomes wet.