Units of textile measurement

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

Units of Measure for Fibers[edit]

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[edit]

Denier /ˈdɛnjər/ or den, a unit of measure for the linear mass density of fibers, is defined as the mass in grams per 9000 meters.[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 112 of a sou). Applied to yarn, a denier was held to be equal in weight to 124 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-denier fibers, but a heavier yarn such as 150 denier is only considered fine if its constituent fibers are individually as thin as 1 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:

1 denier = 1 gram per 9 000 meters
= 0.111 milligrams per meter

In practice, measuring 9000 meters is both time-consuming and unrealistic; generally a sample of 900 meters is weighed and the result multiplied by 10 to obtain the denier weight.

  • 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 manufacture 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).[2]

One can calculate the diameter of a filament yarn using denier with the following formula:

\mathrm{Diameter} = \sqrt{ \frac{\mathrm{Denier}}{9000 \cdot \mathrm{density} \cdot 0.7855} }

with density in grams per cubic centimeter and diameter in millimeters.

Tex[edit]

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.[3] 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.

One can calculate the diameter of a filament yarn using tex with the following formula:

\mathrm{Diameter} = \sqrt{ \frac{\mathrm{Tex}}{1000 \cdot \mathrm{density} \cdot 0.7855} }

with density in grams per cubic centimeter and diameter in millimeters.

S or super S number[edit]

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[edit]

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 [4] (1 yard = 0.9144 meters) lengths (hanks) of worsted yarn that a pound (0.45359237 kilograms) of wool yields. The finer the wool, the more yarn and the higher the count. It has been largely replaced by direct measures.

Yield[edit]

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[edit]

Cotton count[edit]

  • Cotton count is another measure of linear density. It is the number of hanks (840 yd or 770 m) of skein material that weigh 1 pound (0.45 kg). Under this system, the higher the number, the finer the yarn. In the United States cotton counts between 1 and 20 are referred to as coarse counts. A regular single-knit T-shirt can be between 20 and 40 count; fine bed sheets are usually in the range of 40 to 80 count. The number is now widely used in the staple fiber industry.
  • Hank: a length of 7 leas or 840 yards (770 m)
  • One lea – 120 yards (110 m)

Yarn length[edit]

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.

  • Thread: a length of 54 inches (1.4 m) (the circumference of a warp beam)
  • Bundle: usually 10 pounds (4.5 kg)
  • Lea: a length of 80 threads or 120 yards (110 m)[5]

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[edit]

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

Yarn density conversion[edit]

Approximate yarn measurement comparison
Denier m/g Tex Worsted Cotton Woolen (run) Linen (lea)
50 180 5.6 160 106 56 298
75 120 8.3 106 72 37 198
100 90 11.1 80 53 28 149
150 60 16.6 53 35 19 99
200 45 22.2 40 27 14 74
300 30 33.4 27 18 9.3 50
400 22.5 44.4 20 13 7.0 37
500 18 55.5 16 11 5.6 30
700 12.9 77.7 11.4 7.6 4.0 2
1000 9 111 8.0 5.3 2.8 15
1500 6 166 5.3 3.5 1.9 10
2000 4.5 222 4.0 2.7 1.4 7

Fabric[edit]

Because a fabric is sheet-like (i.e., 2-dimensional), it is measured in terms of surface density or in terms of the number of threads involved in a piece of fabric of given size.

Grams per Square Meter / GSM of Fabric[edit]

In the International System of Units, surface density is measured in kilograms per square meter. For fabrics, grams per square meter (GSM) is a more practical unit of measure. We can calculate the GSM of a fabric by the following formulae:

Using Denier, GSM = ((Denier x EPI x 39.37)/9000 + (Denier x PPI x 39.37)/9000))
Using English cotton count, GSM = ((5315/Nec X EPI x 39.37)/9000 + (5315/Nec x PPI x 39.37)/9000))

Process technique to check the above formulae: 1. Weave 1 meter greige fabric. Cut the fabric from the loom. Measure GSM and find the denier/dtex/tex/count you have used.

Process technique to achieve zero defect in dipped or coated fabric. Dipping and coating treatment required high temperatures. To take the greige fabric before dipping, follow the steps 1. Weave 1 meter greige fabric. Cut the fabric from the loom. Measure GSM and find the denier/dtex/tex/count. 2. Put the fabric for required HAS (Hot air shrinkage) testing. 3. Put the fabric in inspection table and observe it. If all the fabric yarn/cords are uniform in length proceed for weaving the required fabric.

The above techniques suggests that the yarn and fabric tensile testing standards should be globally updated to 100 cm.


Mommes[edit]

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. One momme = 4.340 grams per square meter; 8 mommes is approximately 1 ounce per square yard or 35 grams per square meter.

The momme is based on the standard width of silk of 45 inches wide (though silk is regularly produced in 55-inch 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[edit]

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

Thread count or threads per inch (TPI)[6] 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.[7] 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[edit]

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), 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.[8] In 2002, ASTM proposed a definition for "thread count" [9] that has been called "the industry's first formal definition for thread count".[10] 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."[11]

Ends per inch[edit]

Ends per inch (EPI or e.p.i.) is the number of warp threads per inch of woven fabric.[6][12] 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 wraps 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 wraps 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[edit]

Picks per inch (or p.p.i.) is the number of weft threads per inch of woven fabric.[13] A pick is a single weft thread,[14] hence the term. In general, the higher the picks per inch, the finer the fabric is.

References[edit]

  1. ^ a b Haynes, Williams (1946). "XVII: New Fibres: New Fabrics". This Chemical Age. London: Secker and Warburg. p. 217. 
  2. ^ All About Denier "All About Hosiery Denier". 
  3. ^ Collier 1970, p. 3
  4. ^ Collier 1970, p. 74
  5. ^ Curtis 1921, p. Cotton count
  6. ^ a b Schwalbe Tires: What does carcass EPI mean?
  7. ^ Sheets.co.nz
  8. ^ Federal Trade Commission Letter retrieved from NTA website February 9, 2009
  9. ^ Revised Test Method Further Defines Fabric Count
  10. ^ Hometextilestoday.com "Down For the (Thread) Count"
  11. ^ Down For the (Thread) Count – 25 October 2004 – Home Textiles Today
  12. ^ Curtis 1921
  13. ^ Curtis 1921
  14. ^ "Pick." The Oxford English Dictionary. 2nd ed. 1989.

Bibliography[edit]

External links[edit]