PEC EPE Textile flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Tex definition

Tex is the mass in grams of 1000 meters of yarn. It is a direct yarn count system: higher tex means coarser yarn. Tex = 590.5 / Ne (cotton count).

Denier definition

Denier is the mass in grams of 9000 meters of yarn or filament. It is used mainly for continuous filament and silk. Denier = 9 × Tex.

English cotton count (Ne)

Ne is the number of 840-yard hanks in one pound of yarn. It is an indirect count: higher Ne means finer yarn. Ne = 840 / (yarn length in yards per pound).

Metric count (Nm)

Nm is the number of 1000-meter lengths (kilometers) per kilogram of yarn. It is indirect: higher Nm means finer yarn. Nm = 1000 / Tex.

Twist multiplier

Twist multiplier (TM) relates turns per unit length to yarn count. For cotton: TM = TPI / √Ne. For metric: TM = TPM / √Nm. It indicates twist level independent of count.

Yarn tenacity

Tenacity is breaking force divided by linear density, expressed in cN/tex or gf/denier. Tenacity (cN/tex) = breaking force (cN) / yarn tex. It normalizes strength for count.

Woven fabric cover factor

Cover factor K = threads per inch / √(yarn count in Ne). It estimates the fraction of fabric area covered by yarns. For plain weave, fabric cover factor ≈ K_warp + K_weft − (K_warp × K_weft)/28.

Kubelka-Munk K/S

K/S = (1−R)² / (2R), where R is reflectance at λmax. K/S is proportional to dye concentration on the substrate and is used for color strength and recipe prediction.

Drape coefficient

Drape coefficient = (projected area of draped fabric − area of supporting disk) / (area of specimen − area of disk). Values range 0–1; higher values mean stiffer fabric.

Air permeability

Air permeability is the volume of air passing through a unit area of fabric per unit time at a specified pressure differential, usually 100 Pa. It is reported in mm/s or cm³/cm²/s.

Pilling rating scale

Pilling is rated on a 1–5 scale using testers such as Martindale or Random Tumble. Rating 5 means no pilling; rating 1 means severe pilling. Lower twist and loose fibers increase pilling.

Fabric crimp

Crimp is the waviness of yarns in fabric, expressed as percentage: crimp % = (yarn length in fabric − fabric length) / fabric length × 100. It affects extensibility and cover.

Yarn hairiness

Hairiness is the number and length of protruding fibers on yarn surface. It is measured by instruments like Uster Hairiness (H value). Higher hairiness increases pilling and reduces abrasion resistance.

Fabric sett

Sett is the number of threads per unit length in warp and weft, usually ends per inch (EPI) and picks per inch (PPI). It determines fabric density and cover factor.

Tensile strength testing

Tensile testing measures breaking load and elongation using a constant-rate-of-extension tester. Results are reported as breaking strength (N), tenacity (cN/tex), and elongation at break (%).

Tear strength

Tear strength is the force required to propagate a tear in fabric, measured by Elmendorf or tongue tear methods. It depends on yarn strength, fabric structure, and finish.

Bursting strength

Bursting strength is the pressure required to rupture fabric when inflated by a diaphragm or ball. It is reported in kPa or psi and is important for knitted and nonwoven fabrics.

Abrasion resistance

Abrasion resistance is the ability of fabric to withstand rubbing, tested by Martindale or Taber. Results are cycles to failure or mass loss. Higher twist and longer fibers improve it.

Colorfastness to washing

Colorfastness to washing is assessed by change in shade and staining of adjacent fabrics after laundering. It is rated 1–5 using grey scales, with 5 indicating no change.

Colorfastness to light

Colorfastness to light measures fading resistance under exposure to light, rated 1–8 using blue wool standards. Higher ratings indicate better lightfastness.

Shrinkage

Shrinkage is the dimensional change of fabric after washing or relaxation, expressed as percentage of original length or width. It is affected by fiber type, yarn twist, and finishing.

Fabric hand

Fabric hand describes tactile properties such as softness, smoothness, and stiffness. It is evaluated by subjective touch or instruments like Kawabata (KES) and Fabric Assurance by Simple Testing (FAST).

Warp and weft

Warp yarns run lengthwise in woven fabric; weft (filling) yarns run crosswise. Warp yarns usually have higher twist and strength to withstand weaving tension.

Plain weave

Plain weave is the simplest woven structure with a 1-up, 1-down interlacing. It provides high dimensional stability and cover but lower drape and tear strength than twill or satin.

Twill weave

Twill weave produces diagonal lines with a 2-up, 1-down or similar interlacing. It offers better drape and diagonal stretch than plain weave and is common in denim.

Satin weave

Satin weave has long floats with few interlacing points, giving high luster and smooth hand but lower abrasion resistance and higher snagging tendency.

Knit fabric structure

Knitted fabrics are formed by interlooping yarns. Weft knits (jersey) stretch more in width; warp knits (tricot) are more stable. Stitch density affects cover and extensibility.

Nonwoven fabric

Nonwoven fabric is made from fibers bonded by mechanical, thermal, or chemical means without weaving or knitting. Properties depend on fiber type, web formation, and bonding method.

Fiber fineness

Fiber fineness is expressed as linear density in dtex or denier. Finer fibers give softer hand, better drape, and higher cover but are more prone to pilling.

Moisture regain

Moisture regain is the percentage of moisture in a material calculated on its oven-dry weight. It affects comfort, static, and dimensional stability of textiles.

Fabric porosity

Fabric porosity is the fraction of void space in fabric volume. It influences air permeability, thermal insulation, and liquid penetration. Porosity = 1 − (fabric bulk density / fiber density).

Dye exhaustion

Dye exhaustion is the percentage of dye transferred from the dyebath to the substrate during dyeing. Higher exhaustion means less dye waste and lower effluent load.