Percale is a closely woven plain-weave fabric often used for bed linens.
The term describes the weave of the fabric, not its content, so percale can be a 50/50 blend of cotton and polyester, 100% cotton, or a blend of other fabrics in any ratio. A percale weave has a thread count of about 200 or higher, and is noticeably tighter than the standard type of weave used for bed-sheets. It has medium weight, is firm and smooth with no gloss, and warps and washes very well. It is made from both carded and combed yarns. Percale fabrics are made in both solid colors and printed patterns. The finish of the fabric is independent of its weave, so it can be either printed or unprinted.
Percale was originally imported from India in the seventeenth and eighteenth centuries, then manufactured in France. The word may originate from the Persian pargalah, 'rag', although the Oxford English Dictionary (Dec. 2005) has traced it only as far as 18th-century French.
The standard measurement for weight and quality of fabrics is grams per square meter, usually abbreviated as GSM. This is the accepted standard in the United States as well as in foreign countries. Towels and bath robes typically vary from 300 to 800 GSM; other fabrics may have values as low as 100 GSM
Thread count is a measure of the coarseness or fineness of fabric. It is measured by counting the number of threads contained in one square inch of fabric, including both the length (warp) and width (weft) threads. It is used especially in regard to cotton linens such as bed sheets.
Thread count is a simple measure of fabric quality, so that "standard" cotton thread counts are around 150 while good-quality sheets start at 180 and a count of 200 or higher is considered percale. Extremely high thread counts (typically over 500) tend to be misleading as they usually use 'plied' yarns. i.e. one yarn that is made by twisting together multiple finer threads. For marketing purposes, a fabric with 250 yarns in both the vertical and horizontal direction could have the component threads counted to a 1000 thread count although "according to the National Textile Association, which cites the international standards group ASTM, accepted industry practice is to count each thread as one, even threads spun as two- or three-ply yarn. The Federal Trade Commission agrees and recently issued a warning that consumers 'could be deceived or misled' by inflated thread counts."
In 2002, ASTM proposed a definition for "thread count" that has been called "the industry's first formal definition for thread count".
Older, informal definitions include the "U.S. Customs Harmonized Tariff Schedule, which states each ply should be counted as one using the "average yarn number.""