Grams per square metre (GSM) Fabric weight is measured in
grams per
square metre or g/m2 (sometimes abbreviated as GSM). GSM is the metric measurement of the weight of a fabric—it is a critical
parameter for any textile product. Fabric weight may affect many physical properties of the fabric such as density, thickness and strength. Typically, cheap T-shirt fabric is approximately 150 g/m2. The GSM of fabric helps in determining the consumption, cost and application. Higher GSM corresponds to thicker and heavier construction.
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 wide (though silk is regularly produced in widths and uncommonly in larger widths). The usual range of momme weight for different weaves of silk are: •
Habutai—5 to 16 mm •
Chiffon—6 to 8 mm (can be made in double thickness, i.e. 12 to 16 mm) •
Crepe de Chine—12 to 16 mm •
Gauze—3 to 5 mm •
Raw silk—35 to 40 mm (heavier silks appear more "wooly") •
Organza—4 to 6 mm •
Charmeuse—12 to 30 mm The higher the weight in mommes, the more durable the weave and the more suitable it is for heavy-duty use. Also, the heavier the silk, the more opaque it becomes. This can vary even within the same weave of silk: for example, lightweight charmeuse is translucent when used in clothing, but 30-momme charmeuse is opaque.
Thread count Thread count, also called
threadcount or
threads per inch (
TPI), 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 centimetre, 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 with cotton
linens such as
bed sheets, and has been known to be used in the classification of towels. There is a common misconception that thread count is an important consideration when purchasing bedding. However, linen experts claim that beyond a thread count of 400, there is no difference in quality. They further highlight that sheet material is of greater importance than thread count. The amount of thread that can fit into a square inch of fabric is limited, suggesting that bedding beyond 400 count is likely a marketing strategy. Inflated thread counts are usually the result of including the number of strands in a twisted yarn in the claimed thread count.
Industry standard Thread count is often used as a measure of fabric quality, thus "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) extremely high thread counts (typically over 500) mislead 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 1,000 thread count although according to the
National Textile Association (NTA), which cites the international standards group ASTM International, 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 the NTA agreed 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". A small number of 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."
In tartans In the context of
tartans, thread counts are used not for determining coarseness, but rather for recording and reliably repeating the cross-striped pattern of the cloth. Such a thread count (which for the typical
worsted woollen cloth used for a kilt must in total be divisible by 4) is given as a series of colour-code and thread-count pairs. Sometimes, with typical symmetrical (reflective) tartans, slash (/ ) markup at the ends is used to indicate whether (and how much of) a "pivot" colour is to be repeated when the design is mirrored and repeated backwards. For example, calls for a pattern of (left to right) blue, white, blue, red, black, green, and white, and indicates that when mirrored the two white threads (going one direction) or 24 blue threads (going the other) are repeated after mirroring, resulting in a total of 4 white going rightward and 48 blue heading left. This is known as a
half-count at pivot thread count. The same
sett (technically a half-sett) could also be represented , in a
full-count at pivot thread count; this indicates that after the four white threads, the pattern resumes backwards with 24 green without repetition of any of the white count. The old style, without slash markup——is considered ambiguous, but is most often interpreted as a full count. The comparatively rare non-symmetrical tartans are given in full setts and are simply repeated without mirroring.
Ends per inch Ends per inch (EPI or e.p.i.) is the number of
warp threads per inch of woven fabric. In general, the higher the ends per inch, the finer the fabric is. 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. The number of times the thread can be wrapped around a ruler in adjacent turns over an inch is called the
wraps per inch.
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 depends 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 (or p.p.i.) is the number of
weft threads per inch of woven fabric. hence the term. In general, the higher the picks per inch, the finer is the fabric.
Courses and wales Loops are the building blocks of
knitted fabrics, and courses and wales in knitted fabrics are importantly similar to ends and pick in woven fabrics. The knitting structure is formed by intermeshing the loops in consecutive rows. •
Courses are the total number of horizontal rows measured in per inch or per centimetre. The course is a horizontal row of loops formed by all the adjacent needles during one revolution. Course length is obtained by multiplying loop length with the number of needles involved in the production of the course. •
Wales are the number of vertical columns measured in per inch or per centimetre. • Because the number of courses and wales per inch or per centimetre infers (more or less) the tight and loose knitting.
Stitch or loop density is the total number of loops in a unit area such as per square centimetre or per square inch. •
Stitch/loop length is a major factor in a knitted fabric's overall quality, affecting dimensional stability, drape and appearance, etc. Loop length is the length of yarn contained to form a loop.
Air permeability Air permeability is a measure of the ability of
air to pass through a fabric. Air permeability is defined as "the volume of air in cubic centimetres (cm3) which is passed through in one second through 100 cm2 of the fabric at a pressure difference of 10 cm head of water", also known as the
Gurley unit. It is standardized by, among others, norm ASTM D737-18 and norm ISO 9237-1995. Factors that affect air permeability include
porosity, fabric thickness and construction, yarn density, twist,
crimp, layering, and moisture within the fabric. The concept of air permeability is important for the design of
active wear and
insect netting. ==References==