Intermediate Textile interview questions

150 questions with answers (TEX-151 to TEX-300). Try each one aloud before reading the answer.

Textile Fibers

TEX-151 · What is the difference between tex and denier?

Both are direct systems. Tex is grams per 1000 m and denier is grams per 9000 m, so denier = 9 × tex. Decitex (dtex), grams per 10,000 m, is common for filaments.

TEX-152 · Why does cotton get stronger when wet while viscose gets weaker?

Cotton's highly crystalline, well-oriented cellulose is plasticized by water, which relieves stress concentrations, so wet strength rises. Viscose has lower crystallinity and degree of polymerization. Water swells its amorphous regions and breaks hydrogen bonds, so it can lose roughly half its strength.

TEX-153 · What is the structure of a cotton fiber?

A flat, convoluted, ribbon-like tube. From outside in, it consists of a waxy cuticle, a thin primary wall, a thick secondary wall of spiralling cellulose fibrils laid in daily growth layers, and a central lumen. Its convolutions help fiber cohesion in spinning.

TEX-154 · Why does wool felt?

Its surface scales cause a directional friction effect, so fibers migrate preferentially root-first. With moisture, heat and mechanical agitation they ratchet together and entangle permanently. Shrink-resist treatments such as chlorination or polymer coating mask the scales.

TEX-155 · How do crystallinity and orientation affect fiber properties?

Higher crystallinity raises strength, modulus and chemical resistance but lowers moisture absorption and dye uptake. Higher orientation along the fiber axis increases tenacity and reduces elongation.

TEX-156 · What are the glass transition and melting temperatures of PET?

PET has a Tg of about 70–80 °C and a melting point of about 250–260 °C. Above Tg, chain segments become mobile, which allows dye diffusion and heat setting.

TEX-157 · How do melt, wet and dry spinning differ?

Melt spinning extrudes molten polymer that solidifies on cooling (PET, nylon, PP). Wet spinning extrudes a polymer solution into a coagulation bath (viscose, some acrylics). Dry spinning extrudes a solution into hot air that evaporates the solvent (acetate, spandex).

TEX-158 · Why are synthetic filaments drawn after spinning?

Drawing stretches the filaments several times their length. This orients polymer chains along the axis and increases crystallinity, so tenacity and modulus rise while elongation falls. The draw ratio is chosen for the end use.

TEX-159 · What are POY, FDY and DTY?

POY (partially oriented yarn) is spun at high speed with partial orientation and is used as feedstock for texturing. FDY (fully drawn yarn) is spun and drawn in one step, giving a flat yarn. DTY (draw-textured yarn) is POY simultaneously drawn and false-twist textured, giving bulk and stretch.

TEX-160 · How do fineness and maturity of cotton affect processing?

Finer fibers give more fibers per yarn cross-section, so yarn is stronger and more even. Immature fibers have thin walls, break easily, form neps and dye pale. Micronaire combines both effects.

TEX-161 · Why does silk have a natural luster?

Its fibroin filaments have a smooth surface and a roughly triangular cross-section that reflects light like a prism. Degumming removes the dull sericin coating and reveals the luster.

TEX-162 · Why does polyester build up static and resist moisture?

PET has few polar, hydrophilic groups and a compact crystalline structure, so its regain is only about 0.4%. With almost no surface moisture to dissipate charge, static builds up. Hydrophilic finishes or blending with cotton help.

TEX-163 · What are bicomponent fibers?

Fibers made from two polymers extruded together in a side-by-side, sheath–core or islands-in-the-sea arrangement. Uses include self-crimping (side-by-side), thermal bonding with a low-melt sheath, and microfibers produced by dissolving the "sea".

Yarn Manufacturing & Spinning

TEX-164 · How do ring spinning and rotor spinning differ?

Ring spinning drafts roving and inserts twist with a ring and traveller. It gives the strongest, finest yarns but has low delivery speed and needs a roving stage. Rotor spinning feeds sliver to an opening roller and rotor, runs many times faster and makes larger packages. Its yarns are more even but weaker and suit coarser counts.

TEX-165 · How do you convert English count (Ne) to tex?

tex = 590.5 ÷ Ne. For example, 30 Ne = 590.5 ÷ 30 ≈ 19.7 tex. Conversely, Ne = 590.5 ÷ tex.

TEX-166 · What is twist multiplier and how is TPI calculated?

Twist multiplier (TM) expresses twist level independent of count: TPI = TM × √Ne. Warp yarns use higher TM for strength and knitting yarns use lower TM for softness.

TEX-167 · How is draft calculated from linear densities?

Draft = linear density fed ÷ linear density delivered (direct system). With doublings, draft = (number of ends fed × feed tex) ÷ delivered tex. Mechanical draft is calculated from roller speeds and diameters.

TEX-168 · What is compact spinning?

A ring-spinning variant that adds a pneumatic or mechanical condensing zone after the front drafting rollers. It almost eliminates the spinning triangle, so edge fibers are bound in. This cuts hairiness and raises strength.

TEX-169 · What is air-jet (vortex) spinning?

A drafted fiber strand is twisted by a swirling air vortex in a nozzle. Wrapper fibers spiral around a parallel core. Delivery speeds are very high and the yarn has low hairiness and good pilling resistance, though it feels harsher than ring yarn.

TEX-170 · What is the spinning triangle?

The triangular zone of fibers between the front roller nip and the point where twist reaches the strand in ring spinning. Edge fibers there are poorly controlled, which causes hairiness and lost strength.

TEX-171 · How much noil is removed in combing and what is the trade-off?

Typically about 12–20% of the lap, depending on the required yarn quality. Higher noil improves evenness, strength and luster but increases raw-material cost.

TEX-172 · What are the roles of the licker-in, cylinder, flats and doffer in a card?

The licker-in opens the feed and removes trash. The cylinder and flats card the fibers between opposing wire points, individualizing them and removing neps and short fibers. The doffer collects the fiber web from the cylinder and passes it on for condensing into sliver.

TEX-173 · What is an autoleveller?

A control system on the card or drawframe that measures sliver thickness and adjusts the draft in real time to correct mass variation. This keeps the delivered sliver count uniform.

TEX-174 · Why must there be an even number of passages between the card and comber?

Card sliver has mostly trailing fiber hooks. Each passage reverses the hook direction. The comber removes leading hooks best, so an even number of intermediate passages presents leading hooks to the comber.

TEX-175 · How is ring frame production per spindle calculated?

Delivery (m/min) = spindle rpm ÷ TPM. Production (g/h) = delivery × 60 × tex ÷ 1000. For example, 18,000 rpm ÷ 900 TPM = 20 m/min, and 20 × 60 × 20 tex ÷ 1000 = 24 g/h per spindle at 100% efficiency.

TEX-176 · What causes yarn hairiness?

Fiber ends protruding from the spinning triangle, short fibers, high spindle speed and balloon, worn travellers, worn rings and low relative humidity. Hairiness is lowered by compact spinning, combing and air-splicing during winding.

Weaving Preparation & Weaving

TEX-177 · Why is warp sized but weft not?

Warp ends suffer repeated abrasion and cyclic strain from healds, reed and shed opening at every pick. Weft is inserted once with little stress, so it needs no sizing.

TEX-178 · What size add-on is typical and why does it matter?

For staple cotton, add-on is commonly about 8–15% of yarn weight. It is higher for fine, dense constructions and fast looms. Too little leaves the yarn hairy and weak. Too much makes it stiff and brittle, causes shedding and raises desizing load.

TEX-179 · How do twill and satin weaves differ structurally?

Twill offsets interlacing by one end each pick, which forms a diagonal line, as in a 2/1 or 3/1 twill. Satin distributes interlacings so that no two adjacent ones touch. This gives long floats and a smooth, lustrous face but lower abrasion resistance.

TEX-180 · How is cover factor calculated for cotton fabrics?

Peirce's cover factor for one direction is K = threads per inch ÷ √Ne. Fabric cover factor Kc = K₁ + K₂ − (K₁ × K₂) ÷ 28, where 28 represents full cover.

TEX-181 · How does an air-jet loom insert weft?

A main nozzle accelerates the weft with compressed air into a profiled reed channel. Relay nozzles along the width keep it moving. It reaches the highest insertion rates but consumes a lot of compressed air.

TEX-182 · How does a rapier loom insert weft?

A giver rapier carries the weft to the centre of the shed and hands it to a taker rapier, which draws it across (flexible or rigid rapiers). It is very versatile for fancy yarns, colours and heavy fabrics.

TEX-183 · How does a projectile loom work?

A small steel gripper projectile, launched by a torsion bar, carries the weft across the shed and is returned beneath it. It suits wide, heavy and technical fabrics.

TEX-184 · What are the limitations of water-jet looms?

They insert weft with a water jet, so the yarns must be hydrophobic (mainly polyester and nylon filament). The fabric is wet and must be dried. Hydrophilic yarns such as cotton cannot be woven.

TEX-185 · What is weft insertion rate?

Weft insertion rate (m/min) = picks per minute × reed width in use (m). It compares looms of different widths. For example, 800 ppm × 1.9 m = 1520 m/min.

TEX-186 · What is the difference between positive and negative shedding?

In positive shedding, the mechanism drives heald frames both up and down. In negative shedding, it drives them one way only and springs or weights return them. Tappet (cam) shedding is often negative.

TEX-187 · Why does a loom need a controlled let-off?

Let-off releases warp so that warp tension stays constant as the beam diameter shrinks. Unstable tension causes broken ends, thick or thin places and pick-density variation. Modern looms use electronic let-off with tension sensors.

TEX-188 · How is loom production in metres per hour calculated?

Fabric length per minute (in) = ppm ÷ PPI. For example, 600 ppm at 60 PPI gives 10 in/min, which is 0.254 m/min or about 15.2 m/h at 100% efficiency. Multiply by efficiency to get the actual rate.

TEX-189 · What are common weaving defects?

Broken ends, missing picks and double picks, floats, reed marks, starry warp, thick and thin places, weft bars, temple marks and oil stains.

Knitting

TEX-190 · Why is knitted fabric more extensible than woven fabric?

Its loops can deform, straighten and slip relative to each other under load. In woven fabric, nearly straight interlaced yarns can extend only by losing crimp and stretching the yarn.

TEX-191 · What is tightness factor in knitting?

Tightness factor K = √tex ÷ l, with loop length l in mm. Higher K means a tighter fabric with lower extensibility, better dimensional stability and higher GSM per loop.

TEX-192 · What causes spirality in single jersey?

Twist liveliness of the yarn torques the loops, so wales skew over the fabric. Multifeeder course inclination also contributes. It is reduced by lower TM, plied or steamed yarn, alternating S/Z yarns, and compacting or proper finishing.

TEX-193 · What does the cam system do on a circular knitting machine?

Cams fixed in the cam box drive needle butts up and down as the cylinder rotates. Their profile selects knit, tuck or miss and sets the knitting depth, which sets stitch length.

TEX-194 · How are machine gauge and yarn count related?

Higher gauge has finer needles and smaller hooks, so it needs finer yarn. Using too coarse a yarn causes needle breakage and holes, while too fine a yarn gives a sleazy fabric. Manufacturers give recommended count ranges for each gauge.

TEX-195 · How is the production of a circular knitting machine estimated?

kg/h = rpm × 60 × feeders × needles × stitch length (mm) × tex ÷ 10⁹, multiplied by efficiency. Needles = π × diameter (in) × gauge.

TEX-196 · What is flat-bed knitting?

Knitting on two straight needle beds with a carriage traversing back and forth. It can shape panels by narrowing and widening (fully fashioned) or produce complete seamless garments, and is common for sweaters and collars.

TEX-197 · How are guide bars and laps used in warp knitting?

Guide bars carry warp ends and swing between needles (overlap) and sideways (underlap) to wrap yarn around the needles. Open or closed laps and the lapping notation of each bar define structures such as tricot, locknit and sharkskin.

TEX-198 · Why does single jersey curl at the edges?

All loops are drawn to one side, so the bent yarn is out of balance. The edges curl toward the back at the wales' ends and toward the face at the courses' ends. Balanced structures such as rib and interlock do not curl.

TEX-199 · How is piqué (lacoste) produced?

By combining knit and tuck stitches in a repeat on single-jersey machines. The held tuck loops create a honeycomb-like cellular surface that is more porous and stable than plain jersey.

TEX-200 · What is stitch density?

Stitch density = courses per cm × wales per cm, giving loops per cm². It depends mainly on stitch length and relaxation state. Fabric is measured after full relaxation for specifications.

TEX-201 · Why are positive yarn feeders used?

They deliver a fixed yarn length per revolution regardless of package or tension variation. This keeps stitch length uniform across all feeders and prevents barré and GSM variation.

TEX-202 · What are common knitting faults?

Holes, drop stitches, needle lines (a damaged needle), barré (yarn or tension variation between feeders), press-off, oil spots, sinker lines and spirality.

Nonwovens

TEX-203 · What is a nonwoven fabric?

A sheet of fibers or filaments bonded mechanically (needling, hydroentangling), thermally or chemically, without weaving or knitting. It is made directly from fibers or polymer and skips the yarn stage.

TEX-204 · What are the steps in a spunbond line?

Polymer is melted and extruded through spinnerets, and the filaments are quenched with air. They are drawn aerodynamically for orientation, laid randomly on a suction belt, and bonded, typically by thermal point calendering, before winding.

TEX-205 · Why is meltblown web effective for filtration?

Its fibers are very fine, typically a few micrometres in diameter, and randomly entangled. This creates small pores and a huge surface area that capture particles by interception and diffusion, at low basis weight.

TEX-206 · How does punch density affect needle-punched fabric?

Higher punch density increases fiber entanglement, density and strength up to an optimum. Beyond it, fibers break and strength falls. Penetration depth and needle type also govern the structure.

TEX-207 · What are the advantages of spunlace nonwovens?

They contain no binder, so they are soft, clean and drapeable, have good strength and absorbency, and feel textile-like. These features suit wet wipes, medical dressings, cosmetic pads and surgical drapes.

TEX-208 · How does calender point bonding differ from through-air bonding?

Calender bonding presses the web between heated engraved and smooth rolls, fusing discrete points into a thin, strong, flat fabric. Through-air bonding blows hot air through the web to melt binder fibers, giving a bulky, soft, lofty product.

TEX-209 · Why are sheath–core bicomponent fibers used in thermal bonding?

The low-melting sheath (for example PE) fuses to bond fibers while the higher-melting core (for example PP or PET) stays intact. This keeps fiber integrity and strength at bond points.

TEX-210 · What is airlaid nonwoven used for?

Short fibers, often fluff pulp with binder fibers, are formed by air into a bulky, isotropic web. It is used in absorbent cores, table napkins and wipes.

TEX-211 · What is electret charging of meltblown media?

Electrostatic charge is embedded in the fibers, for example by corona charging. The charged fibers attract and hold submicron particles, so filtration efficiency rises without extra pressure drop.

TEX-212 · Why are nonwovens often anisotropic in strength?

Carding and fast laying align fibers mostly in the machine direction, so MD strength exceeds CD strength. Cross-lapping, randomizing rolls or airlaying improve the MD:CD ratio.

TEX-213 · What is the function of a cross-lapper?

It traverses a light carded web back and forth across a slow-moving apron, building many layers at an angle. This increases weight and width and improves cross-direction strength before needling.

TEX-214 · How does wet-laid nonwoven differ from paper?

Both form on a screen from dilute slurry. Wet-laid nonwovens use longer or synthetic fibers, need even greater dilution, and are bonded by binders or thermal means rather than hydrogen bonding alone. They are stronger and more porous.

TEX-215 · What are basis weight and thickness in nonwovens?

Basis weight is mass per area in g/m². Thickness is measured under specified pressure. Together with fiber density they determine porosity, which governs filtration, absorbency and bulk.

Wet Processing & Pretreatment

TEX-216 · What is mercerization?

Treating cotton with concentrated caustic soda, typically about 20–25% NaOH, under tension and at room or low temperature, followed by washing and neutralizing. The fibers swell and become round, which increases luster, strength, dye uptake and dimensional stability.

TEX-217 · Why does hydrogen peroxide bleaching need alkali and stabilizer?

Alkali, at about pH 10.5–11, activates H₂O₂ to the perhydroxyl ion (HO₂⁻), which bleaches. Stabilizers such as sodium silicate or organic stabilizers control decomposition and bind metal ions, preventing uncontrolled breakdown and fiber damage.

TEX-218 · How does enzymatic desizing work?

α-Amylase hydrolyses starch into soluble dextrins and sugars at its optimum pH and temperature. It does not attack cellulose, so desizing is gentle and the waste is easy to treat.

TEX-219 · What is bioscouring?

Scouring with alkaline pectinase enzymes that break down the pectin binding waxes to the fiber. It works at milder pH and temperature than caustic scouring, saves water and energy, and gives a softer handle, though wax removal is less complete.

TEX-220 · What is combined scouring and bleaching?

A single-bath process that uses NaOH, H₂O₂, stabilizer and wetting agent together. It saves time, water and energy compared with separate stages and is widely used for cotton knits.

TEX-221 · How does causticization differ from mercerization?

Causticization uses lower NaOH concentration, often slack (without tension). It improves dye uptake and handle but gives little luster. Full mercerization uses higher concentration under tension for maximum luster.

TEX-222 · At what temperature is polyester heat set?

Typically about 180–210 °C for tens of seconds on a stenter, well above Tg and below the melting point. Nylon 6 is set at lower temperatures. Too high a temperature yellows the fabric and reduces dyeability.

TEX-223 · Why is singeing done before desizing?

Starch size helps bind loose fibers so that they burn cleanly. Any burnt residue and sparks are then quenched and removed in the following desizing bath, which also stops afterglow.

TEX-224 · Why is residual peroxide removed before reactive dyeing?

Leftover H₂O₂ can oxidize and degrade reactive dyes, giving lighter or uneven shades. It is removed with catalase enzyme (peroxide killer) or reducing agents before dyeing.

TEX-225 · How does an optical brightener make fabric look whiter?

It absorbs invisible UV around 340–370 nm and fluoresces blue light around 420–470 nm. The blue offsets the yellowish cast and increases total reflected visible light, so whiteness index rises.

TEX-226 · What is weight reduction of polyester?

Controlled hydrolysis of PET fabric surfaces with hot NaOH, removing a set percentage of mass. The thinner, pitted fibers give a softer, silk-like handle and better drape.

TEX-227 · How is wool made shrink-resistant?

By oxidative chlorination, which modifies the scales, often followed by a polymer resin that masks them (chlorine–Hercosett type). Chlorine-free plasma and enzyme routes are also used.

TEX-228 · What is the cold pad-batch process?

Fabric is padded with chemicals, for example reactive dye plus alkali or a bleach liquor, batched on a roll, wrapped and rotated for many hours at room temperature, then washed. It uses little energy and water.

Dyeing

TEX-229 · Why do reactive dyes need alkali for fixation on cotton?

Alkali (soda ash or caustic) ionises cellulose hydroxyl groups into cellulosate anions, which attack the dye's reactive group to form a covalent bond. Without alkali, the dye only adsorbs and washes off.

TEX-230 · Why does reactive dye hydrolysis lower colour yield?

In the alkaline bath the reactive group can react with water instead of the fibre. Hydrolysed dye can no longer bond, so it is washed off during soaping, lowering colour yield and adding colour to the effluent.

TEX-231 · Why is polyester dyed at about 130 °C with disperse dyes?

Polyester's glass transition is around 70–80 °C. Well above it, polymer chains move enough to open free volume, so the non-ionic disperse dye can diffuse into the fibre at a practical rate. High-temperature, pressurised machines or carriers make this possible.

TEX-232 · How do bifunctional reactive dyes improve fixation?

They carry two reactive groups, often of different types, giving two chances to bond with cellulose. Fixation rises from about 60–70% to 80–90%, reducing wasted dye and wash-off load.

TEX-233 · Why are vat dyes reduced before dyeing and oxidised afterwards?

Vat dyes are insoluble pigments. Sodium hydrosulphite in alkali reduces them to a soluble leuco form that penetrates cotton; oxidation then regenerates the insoluble pigment inside the fibre, giving excellent wash and light fastness.

TEX-234 · Why are acid dyes suitable for wool and nylon but not cotton?

Wool and nylon contain amino groups that become positively charged in an acidic bath, attracting anionic acid dyes through ionic bonds. Cotton has no such cationic sites, so acid dyes have little affinity for it.

TEX-235 · How does a lower liquor ratio affect dyeing performance?

A lower ratio raises dye and chemical concentration, improving exhaustion and cutting water, steam and effluent per kilogram. If circulation is poor, the fabric may dye unevenly, so machine design must keep liquor flow adequate.

TEX-236 · Why does shade shift after soaping a vat-dyed fabric?

Soaping at the boil removes loose surface pigment and lets dye molecules aggregate or crystallise into their stable form inside the fibre. This changes hue and brightness toward the true, more fast shade.

TEX-237 · How do you control the rate of exhaustion to avoid unlevel dyeing?

Control the temperature rise rate, add salt and alkali in portions, use levelling agents and ensure good liquor circulation. Keeping dye uptake gradual gives time for even distribution before fixation.

TEX-238 · Why are polyester-cotton blends usually dyed in two stages?

Each fibre needs a different dye class: disperse dyes for polyester at high temperature and reactive or vat dyes for cotton in alkali. Two stages let each run under its own best conditions; one-bath methods save time but compromise conditions.

TEX-239 · Why is cationic dye used for acrylic fibre?

Acrylic fibres contain anionic groups (sulphonate or carboxylate) from comonomers, which attract cationic (basic) dyes, giving bright shades with good fastness on acrylic.

TEX-240 · How is shade matching done in a dyehouse laboratory?

A spectrophotometer measures the target and the lab dyeing; colour-matching software proposes a recipe and colour difference is evaluated in CIELAB ΔE units under standard illuminants to check for metamerism. The lab recipe is then scaled to bulk.

Printing & Finishing

TEX-241 · Why does the rheology of a printing paste matter?

The paste must be shear-thinning so it flows through the screen under the squeegee but quickly recovers viscosity on the fabric, giving sharp outlines without bleeding. Wrong rheology gives poor penetration or flushed edges.

TEX-242 · Why does pigment printing give a stiffer hand than reactive printing?

Pigments have no affinity for fibre, so they are held by a cured binder film on the surface. More binder improves rub fastness but stiffens the fabric; reactive dyes bond into the fibre with no film.

TEX-243 · Why is steaming required after reactive printing?

Steaming supplies heat and moisture so dye can diffuse from the dried thickener film into the fibre and react with it. Without steaming fixation is poor and the dye washes off.

TEX-244 · How does discharge printing work?

The fabric is dyed with a dischargeable dye, then printed with a reducing agent that destroys the dye in the printed areas, giving a white pattern, or a coloured one if a discharge-resistant illuminating dye is added to the paste.

TEX-245 · Why does crosslinking resin finishing reduce cotton strength?

Crosslinks between cellulose chains limit chain mobility, so stress concentrates on fewer chains and the fibre becomes more brittle. Wrinkle recovery improves, but tensile and tear strength fall, and some agents release formaldehyde.

TEX-246 · Why must mercerisation be done under tension?

Without tension, cotton swells and shrinks, losing the lustre gain. Holding the fabric under tension while it swells gives round, smooth fibres with higher lustre and strength.

TEX-247 · How does compressive shrinkage control work during finishing?

The fabric is moistened, then compressed lengthwise on a thick rubber belt or felt so it shortens in a controlled way before the consumer washes it. Residual shrinkage drops to around 1%.

TEX-248 · Why can cationic softeners affect absorbency and shade?

Cationic softeners form a hydrophobic surface layer that reduces water absorbency and can slightly change shade or cause yellowing. Hydrophilic silicone softeners are used where absorbency matters.

TEX-249 · How do water-repellent finishes make water bead up?

They lower fabric surface energy below that of water, so drops keep a high contact angle and roll off instead of wetting. Fluorocarbons, silicones and wax-based finishes do this; fluorocarbons are being phased out for health reasons.

TEX-250 · How is flame retardancy given to cotton?

Phosphorus- or nitrogen-based finishes promote char formation and reduce the release of flammable gases. Alternatively, inherently flame-retardant fibres are blended in.

TEX-251 · What limits digital inkjet printing for long production runs?

Ink cost per metre, printing speed and the need for pre-treatment and steaming make it more expensive than rotary screen for long runs, though it wins on setup time and design flexibility.

TEX-252 · What causes print bleeding and how is it prevented?

Excess moisture, low thickener viscosity or poor fabric preparation allow colour to spread. Correct paste rheology, controlled drying and good pre-treatment prevent it.

Textile Testing & Quality Control

TEX-253 · Why does moisture content change tensile test results?

Fibres absorb moisture differently; cotton gets stronger when wet while viscose and wool weaken. Testing at a standard atmosphere removes this variable so results from different labs compare.

TEX-254 · How is fabric tear strength measured?

With methods such as the Elmendorf falling pendulum, tongue or trapezoid tests, measuring the force to propagate a tear. Tear strength predicts resistance to snagging and ripping in use.

TEX-255 · How is colour difference measured instrumentally?

A spectrophotometer measures reflectance and converts it to CIELAB L*, a*, b* values; ΔE (often CMC or CIEDE2000) expresses how far a sample is from the standard. Pass/fail tolerances are agreed with the buyer.

TEX-256 · How is light fastness tested?

Samples and blue wool references are exposed to a xenon arc lamp simulating daylight; fading is compared with the blue wool scale from 1 to 8, where 8 is the most light-fast.

TEX-257 · How is pilling resistance tested?

Using a Martindale or ICI pilling box, fabric is rubbed or tumbled for a set number of cycles and compared with standard photographs to give a grade from 1 to 5.

TEX-258 · How do thin places, thick places and neps affect fabric?

These yarn faults appear as streaks, bars or spots in fabric, reduce strength and cause end breaks. Evenness testers count them per kilometre so spinners can trace their cause.

TEX-259 · Why is CV% used to express yarn quality?

CV% (coefficient of variation) expresses variation relative to the mean, so it compares yarns of different counts. Lower CV means more uniform mass or strength, fewer breaks and better fabric appearance.

TEX-260 · How is fabric air permeability measured?

Air is drawn through a known area at a set pressure drop, and the flow rate per unit area is recorded. It matters for sportswear comfort, filters and airbag fabrics.

TEX-261 · How is fabric bursting strength tested and where is it used?

A diaphragm or ball pushes against the fabric until it bursts, giving a multidirectional strength. It suits knitted and nonwoven fabrics where strip tensile tests are less meaningful.

TEX-262 · Why is shrinkage measured after several wash cycles?

Some shrinkage, especially relaxation and felting shrinkage, continues over several washes. Testing after multiple cycles predicts real consumer behaviour better than a single wash.

TEX-263 · How do HVI measurements guide cotton bale laying?

HVI gives length, strength, micronaire, colour and trash for each bale. Mills mix bales so the blend average and variation stay constant, keeping yarn quality consistent from lot to lot.

TEX-264 · Why is short fibre content important in spinning?

Short fibres are poorly controlled during drafting, causing irregularity, hairiness and weaker yarn. Combing and careful cotton selection reduce short fibre content.

Garment Manufacturing

TEX-265 · How do you improve marker efficiency?

Use CAD nesting software, combine sizes in a marker, allow pieces to rotate where grain and nap permit, and choose the right fabric width. Every percentage point of efficiency saves significant fabric cost.

TEX-266 · Why must napped or one-way fabrics be spread carefully?

Pile and printed one-way fabrics look different from each direction, so all pieces must face the same way. Spreading must be face-up and in one direction, reducing marker efficiency.

TEX-267 · What problems can poor fusing settings cause?

Too much heat or pressure causes strike-through and stiffness; too little gives weak bond strength and bubbling or delamination after washing. Temperature, pressure and time must match the interlining specification.

TEX-268 · How does stitch type affect seam elasticity?

Lockstitch is strong but not very stretchy, so it can crack on knits. Chainstitch, overlock and coverstitch have more thread in the seam and stretch with the fabric.

TEX-269 · What causes seam puckering and how is it reduced?

Thread tension, feed differential, fabric structure and thread shrinkage cause puckering. Balanced tension, a suitable needle and thread, correct feed and lower stitch density reduce it.

TEX-270 · How is line efficiency calculated in garment production?

Line efficiency = (garments produced × SMV)/(operators × working minutes) × 100. It measures how close actual output is to the standard time.

TEX-271 · How does line balancing improve productivity?

It distributes operations so each workstation has similar workload, reducing bottlenecks and idle time and raising output.

TEX-272 · Why do garments of the same size fit differently across brands?

Each brand uses different base body measurements, ease allowances and grade rules. There is no universal size standard, so fit varies even with the same size label.

TEX-273 · How do progressive bundle and unit production systems differ?

Bundle systems move bundles of cut pieces between operators and need more work in progress; unit production systems carry individual garments on overhead hangers, reducing handling and throughput time.

TEX-274 · How is needle damage in knit fabric prevented?

Use ball-point needles of suitable size, correct sewing speed and lubricated fabric. Damaged loops cause holes that grow during wear.

TEX-275 · Why is pressing important in garment finishing?

Pressing shapes garments, sets seams and creases and improves appearance, using heat, moisture and pressure suited to the fibre.

TEX-276 · How is garment fit evaluated?

Through fit sessions on models or dress forms, measuring against spec sheets and checking ease, balance, drape and comfort.

Technical Textiles

TEX-277 · How is a geotextile selected for a road project?

Choose the function (separation, filtration, drainage, reinforcement), then check strength, apparent opening size for soil retention, permeability and installation survivability against the project specification.

TEX-278 · How do medical textiles differ from apparel textiles?

They must meet biocompatibility, sterility and performance standards for uses such as wound dressings, sutures and implants, and they face strict regulatory requirements.

TEX-279 · Why is UHMWPE used in cut-resistant gloves?

Its very long, highly oriented chains give extremely high tenacity and low friction, so blades slide and cannot cut easily. It is lighter and more comfortable than steel mesh.

TEX-280 · How do filter fabrics capture particles?

Through sieving, inertial impaction, interception and diffusion. Fine-fibre nonwovens capture particles efficiently while allowing airflow.

TEX-281 · Why are coated fabrics used for tarpaulins and inflatables?

A PVC, PU or rubber coating makes the fabric waterproof and airtight, while the woven or knitted base carries the load. Coating weight and adhesion to the base decide durability, flexibility and weldability of seams.

TEX-282 · What makes a textile suitable for composite reinforcement?

High-modulus fibres such as glass, carbon or aramid, arranged in woven, knitted or non-crimp forms, provide strength and stiffness when embedded in a resin matrix.

TEX-283 · How do smart textiles sense or respond?

They integrate conductive fibres, sensors or responsive materials to monitor signals such as heart rate or temperature, or to change properties such as colour or insulation.

TEX-284 · Why is breathability important in protective clothing?

It lets sweat vapour escape and reduces heat stress. Membranes such as ePTFE block liquid water but let vapour through.

TEX-285 · How are agrotextiles used in farming?

Shade nets reduce heat and light stress, crop covers protect against frost and insects, insect nets keep pests out without pesticides, and ground-cover mats suppress weeds and conserve moisture. UV-stabilised polyolefins are most common.

TEX-286 · Why do automotive textiles face strict flammability tests?

Seat fabrics, headliners and carpets sit close to occupants and fuel or electrical sources, so they must resist ignition and slow flame spread. Tests such as FMVSS 302 set a maximum burning rate, and fabrics are often treated or chosen to pass.

TEX-287 · How are high-performance sports textiles engineered?

With moisture-wicking fibres, engineered knits, compression structures and functional finishes for comfort, temperature control and performance.

TEX-288 · Why is low air permeability critical for airbag fabric?

The bag must inflate in milliseconds and stay inflated long enough to cushion the occupant, so the fabric must hold gas at high pressure while remaining strong and heat resistant.

Sustainability & Textile Machinery

TEX-289 · How does textile wet processing impact the environment?

It uses large amounts of water, energy and chemicals, producing coloured, salty effluent with high COD. Treatment and process optimisation reduce the impact.

TEX-290 · How can water use in dyeing be reduced?

Use low liquor ratio machines, right-first-time dyeing, combined processes, water recycling and cold pad-batch dyeing.

TEX-291 · What are the limits of recycling textiles back into new fibre?

Blends are hard to separate, fibres shorten during mechanical recycling, dyes and finishes contaminate the feed, and chemical recycling is costly. Design for recyclability helps close the loop.

TEX-292 · Why do air-jet looms consume a lot of energy?

Compressed air is expensive to produce, and the main and relay nozzles use large volumes to carry the weft. Air consumption often dominates the weaving room's energy bill.

TEX-293 · How do you select a weaving machine for a fabric range?

Match weft insertion type to yarns and fabrics: air-jet for high-speed staple and filament fabrics, rapier for versatility and fancy yarns, projectile for wide technical fabrics and water-jet for hydrophobic filament.

TEX-294 · Why is automation important in modern spinning mills?

Auto-doffing, link coners and online monitoring reduce labour, improve quality consistency and increase productivity.

TEX-295 · How are circularity principles applied in textiles?

Through design for recyclability, mechanical and chemical recycling, take-back schemes and use of recycled fibres.

TEX-296 · What is ZDHC and why is it important?

Zero Discharge of Hazardous Chemicals provides a manufacturing restricted substances list and wastewater guidelines, helping brands eliminate hazardous chemicals from supply chains.

TEX-297 · How can energy efficiency be improved in textile mills?

By heat recovery from hot effluent and exhausts, efficient motors with VFDs, compressed-air leak reduction, insulation and process optimisation.

TEX-298 · How does machine speed affect knitting quality?

Higher speeds raise output but increase yarn tension variation, needle wear and faults such as holes and drop stitches. Speed must suit yarn quality and fabric structure.

TEX-299 · What is life cycle assessment (LCA) in textiles?

It evaluates environmental impact from raw material through manufacturing, use and disposal, guiding more sustainable choices.

TEX-300 · How do enzymes make textile processing greener?

Enzymes such as amylase, cellulase and pectinase work under milder conditions, replacing harsh chemicals in desizing, scouring and bio-polishing.

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