Few things say sleeping luxury like a sumptuous pillowcase. It can feel soft on the skin, be gentle on the hair and keep the face cool on a hot night. The fibers in the fabric are responsible for these features of the pillowcase. Silk is a fiber -- like cotton, polyester or rayon -- and can be woven in many ways. Satin is a weave but commonly refers to fabric that is shiny on one side, matte on the other and is most often made of polyester.
Silk is a natural fiber that must be hand harvested. It can be used alone in fabric production or blended with other fibers to increase the fabric's strength and durability. Silk fibers can be long; it is the length of the fiber that gives the finished thread and the fabric its softness. Many threads twisted together produce a thicker fabric, but a bed-linen weight of silk is usually two threads. Fabric this weight is soft and highly prized in pillowcases.
The satin weave is created when four or five shiny lengthwise threads are passed over the corresponding cross-wise threads during the weaving process. This pattern repeats in an offset design, and the exposed threads, laying on the top of the fabric, produce the luster of the satin. The threads can be twisted of any fiber, including silk, but polyester produces a durable, high-luster fabric, and most garment and bed linen satin is 100 percent polyester.
Because silk is a natural fiber, it is resistant to static and retains some warming properties when damp. In pillowcases, it draws moisture away from the face and, even on hot nights, will feel cool on the skin. Fine silk fabric is not particularly strong and is quickly damaged by exposure to the sun. Dust mites, mold and fungi cannot tolerate silk; it is a hypoallergenic fiber. Silk pillowcases can be expensive, wrinkle easily and, unless pre-shrunk, may require dry cleaning.
Satin pillowcases can be woven of threads that are a blend of fibers, and the price of this fabric can be much lower than silk. If the majority of the blend is natural fibers, such as cotton or silk, the satin may feel cool to the touch initially but will feel warm quicker than an all-natural fabric. If the blend is mostly polyester, the satin will be wrinkle resistant and should not shrink, but polyester is subject to static. Polyester-satin has a high luster and is machine washable.