Units of textile measurement

Textile fibers, threads, yarns and fabrics are measured in a multiplicity of units.

Units of measure for fibers

The linear density of a fiber is commonly measured in units of denier or tex. Traditional units include worsted count, cotton count and yield. Tex is more likely to be used in Canada and Continental Europe, while denier remains more common in the United States and United Kingdom. The International System of Units uses kilogram per metre for linear densities; in some contexts, the tex unit is used instead.

Denier

Denier /ˈdɛnjər/ or den (abbreviated D), a unit of measure for the linear mass density of fibers, is the mass in grams per 9000 meters of the fiber.[1] 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 sou). Applied to yarn, a denier was held to be equal in weight to  1⁄24 ounce (1.2 g). Microdenier describes filaments that weigh less than 1 g per 9000 m.

There is a difference between filament and total measurements in deniers. Both are defined as above; but the first relates to a single filament of fiber (commonly called 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 is 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 considered fine only if its fibers are individually as thin as one denier.[1]

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:[2]

1 denier = 1 g / 9000 m
= 0.11 mg/m

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 20 mm) is set to vibrate, and its fundamental frequency measured, allowing the calculation of the mass and thus the titer (linear density).

Tex

Tex is a unit of measure for the linear mass density of fibers, yarns and thread and is defined as the mass in grams per 1000 meters.[5] The unit code is "tex". The most commonly used unit is actually the decitex (abbreviated dtex), which is the mass in grams per 10,000 meters. When measuring objects that consist of multiple fibers, the term "filament tex" is sometimes used, referring to the mass in grams per 1000 meters of a single filament.

Tex is used for measuring fiber size in many products, including cigarette filters, optical cable, yarn and fabric.

S or super S number

Main article: Super S or S number

Not a true unit of measure, S or super S number is an index of the fineness of the wool fiber and is most commonly seen as a label on wool apparel, wool fabric, and yarn.

Worsted count

Yarn spinning factory

Worsted count (or spinning count) is an indirect measure of the fineness of the fiber in a worsted wool yarn expressed as the number of 560-yard[6] (512 m) lengths (hanks) of worsted yarn that a pound (0.45 kg) of wool yields. The finer the wool, the more yarn and the higher the count. It has been largely replaced by direct measures.

Yield

Similar to tex and denier, yield is a term that helps describe the linear density of a roving of fibers. However, unlike tex and denier, yield is the inverse of linear density and is usually expressed in yards/lb.

Tex (g/km) Yield (yards/lb)
550 900
735 675
1100 450
1200 413
2000 250
2200 225
2400 207
4400 113

Yarn and thread

Cotton count

Yarn length

l/m = 1693 × lm/Nec × m/kg, where l/m is the yarn length in meters, lm/Nec is the English cotton count and m/kg is the yarn weight in kilograms.

English cotton count (Nec) is an indirect counting system, that is, the higher the number the finer the yarn.

To convert denier to cotton count: lm/Nec = 5315/ρ/den, where lm/Nec is the cotton count and ρ/den is the density in denier.

To convert tex to cotton count: lm/Nec = 590.5/ρ/tex, where lm/Nec is the cotton count and ρ/tex is the density in tex.

Thread

Thread is a cotton yarn measure, equal to 54 inches (1.4 m).

Mommes

Mommes (mm), traditionally used to measure silk fabrics, the weight in pounds of a piece of fabric if it were sized 45 inches by 100 yards (1.2 m by 90 m). One momme = 4.340 g/m²; 8 mommes is approximately 1 ounce per square yard or 35 g/m².

The momme is based on the standard width of silk of 45 inches (1.2 m) wide (though silk is regularly produced in 55-inch (1.4 m) widths, and, uncommonly, in even larger widths).

The usual range of momme weight for different weaves of silk are:

The higher the weight in mommes, the more durable the weave, and the more suitable it is for heavy-duty use. And, the heavier the silk, the more opaque it becomes. This can vary even between the same kind of silk. For example, lightweight charmeuse is translucent when used in clothing, but 30-momme charmeuse is opaque.

Thread count

Image showing how to determine the number of twists per inch in a piece of yarn

Thread count or threads per inch (TPI)[8] 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 or one square centimeter, including both the length (warp) and width (weft) threads. The thread count is the number of threads counted along two sides (up and across) of the square inch, added together. It is used especially in regard to cotton linens such as bed sheets, and has been known to be used in the classification of towels.

Industry standard

Thread count is often used as a 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. Some, but not all, of the extremely high thread counts (typically over 500) tend to be misleading as they usually count the individual threads in "plied" yarns (a yarn that is made by twisting together multiple finer threads). For marketing purposes, a fabric with 250 two-ply 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 (NTA),[9] 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 in an August 2005 letter to NTA agreed that consumers 'could be deceived or misled' by inflated thread counts.[10] In 2002, ASTM proposed a definition for "thread count"[11] that has been called "the industry's first formal definition for thread count".[12] A minority on the ASTM committee argued for the higher yarn count number obtained by counting each single yarn in a plied yarn and cited as authority the provision relating to woven fabric in the Harmonized Tariff Schedule of the United States, which states each ply should be counted as one using the "average yarn number."[13]

Ends per inch

Ends per inch (EPI or e.p.i.) is the number of warp threads per inch of woven fabric.[8][14] In general, the higher the ends per inch, the finer the fabric is. The current fashion is to wear T-shirts with a higher thread count, such as soft and comfortable "30 single" tee shirt that has 30 threads per inch as contrasted to the standard T-shirt with an 18 thread count per inch.

Ends per inch is very commonly used by weavers who must use the number of ends per inch in order to pick the right reed to weave with. The number of ends per inch varies on the pattern to be woven and the thickness of the thread. Plain weaves generally use half the number of warps per inch for the number of ends per inch, whereas denser weaves like a twill weave will use a higher ratio like two thirds of the number of warps per inch. Finer threads require more threads per inch than thick ones, and thus result in a higher number of ends per inch.

The number of ends per inch in a piece of woven cloth varies depending on the stage of manufacture. Before the cloth is woven, the warp has a certain number of ends per inch, which is directly related to the size reed being used. After weaving the number of ends per inch will increase, and it will increase again after being washed. This increase in the number of ends per inch (and picks per inch) and shrinkage in the size of the fabric is known as the take-up. The take-up is dependent on many factors, including the material and how tightly the cloth is woven. Tightly woven fabric shrinks more (and thus the number of ends per inch increases more) than loosely woven fabric, as do more elastic yarns and fibers.

Picks per inch

Picks per inch/Inch (or p.p.i.) is the number of weft threads per inch of woven fabric.[14] A pick is a single weft thread,[15] hence the term. In general, the higher the picks per inch, the finer the fabric is.

Quality

Martindale

Main article: Martindale (unit)

The unit Martindale quantifies a textile's resistance to abrasion when used for upholstery.

References

Bibliography

External links

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