Denier

Denier listenor den (abbreviated D), a unit of measure for the linear mass density of fibers, is defined as the mass in grams per 9000 meters. The denier is based on a natural reference: a single strand of silk is approximately one denier; a 9000-meter strand of silk weighs about one gram. The term denier comes from the French denier, a coin of small value (worth 1⁄12 of a sou). Applied to yarn, a denier was held to be equal in weight to 1⁄24 of an ounce. The term microdenier is used to describe filaments that weigh less than one gram per 9000 meters.

One can distinguish between filament and total measurements in deniers. Both are defined as above, but the first relates to a single filament of fiber — commonly known as denier per filament (DPF) — whereas the second relates to a yarn.

Broader terms such as 'fine' may be applied, either because the overall yarn is fine or because fibers within this yarn are thin. A 75-denier yarn would be considered fine even if it contains only a few fibers, such as thirty 2.5-denier fibers, but a heavier yarn, such as 150 denier, is only considered fine if its constituent fibers are individually as thin as one denier.

The following relationship applies to straight, uniform filaments:
 * DPF = total denier / quantity of uniform filaments

The denier system of measurement is used on two- and single-filament fibers. Some common calculations are as follows: In practice, measuring 9000 meters is both time-consuming and unrealistic. Generally a sample of 900 meters is weighed, and the result is multiplied by ten to obtain the denier weight. For single fibers, instead of weighing, a machine called a vibroscope is used. A known length of the fiber (usually 20mm) is set to vibrate, and its fundamental frequency measured, allowing the calculation of the mass and thus the titer.
 * A fiber is generally considered a microfiber if it is one denier or less.
 * A one-denier polyester fiber has a diameter of about ten micrometers.
 * In tights and pantyhose, the linear density of yarn used in the manufacturing process determines the opacity of the article in the following categories of commerce: ultra sheer (below 10 denier), sheer (10 to 30 denier), semi-opaque (30 to 40 denier), opaque (40 to 70 denier) and thick opaque (70 denier or higher).

