The Bedding and Bath Planner
Bed Linen 101
Sheets and pillowcases are normally made of linen, cotton, or a cotton-polyester blend. The four principal varieties of cotton, are American upland, Egyptian, pima, and sea island (the finest). Any of the four can be woven into four basic sheeting fabrics: flannel, muslin (a smooth, simple weave), oxford (soft, porous, and rather heavy; also used for shirts), or percale (finely combed and closely woven, easy to launder).
Whichever fabric type you choose, pay attention to thread count -- the number of threads per square inch. The higher the count, the finer the quality of the sheet. The highest count made in the United States is 310; 200 is a good standard.
The label on your linens may also mention finish: mercerized cotton has been treated with alkalis for a distinctive sheen; sanforized cotton has been preshrunk; easy-care and durable press finishes are mechanical or have chemical treatments intended to reduce wrinkling.