bed, exposing the design. In the US and Canada, sheets are often sold in a four-piece set consisting of a fitted sheet, a flat sheet and two pillowcases. In China, a four-piece set consists of a duvet cover, two pillowcases and either a fitted or flat sheet. Fitted sheets are gaining popularity due to their ease of use. Use of good quality elastic make fitted sheets durable. Materials Cotton and cotton blends dominate the market, the most common blend being cotton/polyester. Cotton provides absorbency and a soft hand, while polyester adds durability and wrinkle resistance. Other common fibers used in the manufacturing of bed sheets include linen, silk, Modal and bamboo rayon, lyocell, Microtex or Microfiber, and polypropylene. Polypropylene (olefin) is a hypoallergenic spun-bound material produced at a low cost and typically used in emergency shelters or hospitals as disposable sheeting. Construction The quality of bed sheets is often conveyed by the thread count—the number of threads per square inch of material. In general, the higher the thread count, the softer the sheet, but the weave and type of thread may affect the "hand" of the material so that a sheet with a lower thread count may actually be softer than one with a higher count. Yarn quality also plays a part in the look and feel of sheets, as finer yarns tend to create a finer sheet fabric. The ply also plays a role in how heavy the sheet feels. Ply represents how many fibers are twisted together as the sheet is being created. A 2 ply 300 thread count sheet will feel heavier than a single ply 600 thread count sheet. The most common constructions are muslin, percale, sateen, flannel, and knitted jersey. In a plain weave the warp and weft cross each other one at a time. Sateen has multiple (usually 3–4) over threads and one under. Cleaning Bedsheets should be washed about once a week, using low-temperature water and drying settings. Warm water can be used to eliminate coffee stains, urine or allergens, such as dust mites. Using fabric softeners is not recommended, as they leave behind residue that decreases the fabric's breathability. See also Bed size References Bedding Linens