Towel manufacturing process

Cotton fibre: length, maturity and cleanliness

Cotton is bought by measurable fibre properties rather than by origin name alone. Staple length and length uniformity decide how many fibres overlap in the cross-section of a yarn and how firmly twist can bind them; longer, more uniform fibres spin into finer, stronger and less hairy yarns. Micronaire, an airflow reading that reflects fineness and maturity together, indicates how well the fibre walls have developed. Immature fibres have thin walls, tangle into small knots called neps during processing and take dye less evenly, which can appear later as pale specks on a dyed towel. Trash and colour grades describe cleanliness: leaf and seed-coat fragments must be removed in opening and cleaning, and whatever remains becomes a visible fault or a weak point in the yarn. In the United States these properties are measured instrumentally for every bale^[1].

In a towel, the pile yarn deserves the closest attention because it forms the surface the user touches and the loops that take up water. The ground yarns carry the structure and are chosen mainly for strength and weaving performance.

Spinning: carded, combed, ring-spun and open-end yarns

After opening and blending, carding separates the cotton into a thin web, removes much of the remaining trash and short fibre, and condenses it into a sliver. Carded yarn is spun from that sliver. Combed yarn passes through an extra combing stage that removes a further share of short fibres and neps, which gives a more even, smoother and stronger yarn; the cost is higher because part of the cotton leaves the process as comber waste.

Two spinning systems dominate towel yarns. Ring spinning draws the fibre strand down and inserts twist with a rotating spindle and traveller. It produces a strong yarn with well-aligned fibres and remains the reference system for quality pile yarn. Open-end, or rotor, spinning builds the yarn inside a fast-turning rotor at a much higher production rate. From the same cotton, rotor yarn is more even and less hairy than ring yarn but 10 to 30 percent weaker^[2], and it has a harsher hand, so it appears mainly in ground and weft yarns and in economy towels. Reviews of terry research also report that ring-spun pile yarn absorbs water faster than rotor-spun yarn^[5].

Yarn fineness is stated as a count. Towel mills generally use the English cotton count (Ne), the number of 840-yard hanks in one pound of yarn, so a higher number means a finer yarn; the tex system, grams per 1,000 metres, runs the other way. In one documented Indian terry cluster, ground warps are carded two-ply yarns of Ne 20/2 or 24/2, chosen because ground ends carry the highest tension in weaving, while pile warps are combed single yarns of Ne 16 or 20^[3]. That division is typical: strength in the ground, softness and bulk in the pile.

Twist holds the fibres together. More twist raises strength up to a point, but it also packs the fibres tightly, which makes loops firmer and leaves less space between the fibres to hold water. Low-twist and zero-twist pile yarns were developed mainly to raise absorbency^[5]. Zero-twist yarns are made by twisting cotton together with a water-soluble fibre that is dissolved out during wet processing, leaving the cotton almost untwisted. The trade-off is durability: the less twist a pile yarn has, the more easily fibres shed and loops lose definition over repeated laundering.

Ground warp, pile warp and weft

A terry fabric is built from three sets of yarn. The ground warp runs lengthwise under high tension and, interlaced with the weft, forms the base cloth that holds the towel together. The pile warp also runs lengthwise, but it is let off under low, controlled tension so it can be pushed out of the plane of the cloth to form loops. The weft, or filling, crosses the width of the fabric and locks both warps in place. Because each loop consumes extra length, the pile warp is used up several times faster than the ground warp, so the two are wound on separate beams and fed independently on the loom.

Warping winds hundreds or thousands of ends from a creel onto these beams at even tension; uneven tension shows up later as streaks or irregular pile. Ground warp yarns are rubbed constantly by the heddles and reed, so they are usually sized with a starch or synthetic film that protects them during weaving and is removed afterwards. Practice for pile warps varies, and plied pile yarns are often woven with little or no size. Before weaving, every end is drawn through its drop wire, heddle and reed dent in the order the design requires.

Terry weaving: how the loops are formed

Terry weaving is ordinary dobby or jacquard weaving with one special feature: the beat-up changes position. In a three-pick terry, the first two weft picks of each group are deliberately stopped short of the cloth fell, leaving a gap called the loose-pick distance. On the third pick the full beat-up pushes all three picks together against the fell. The tightly held ground warp cannot follow, but the slack pile warp, gripped between the picks, is carried forward and buckles out of the cloth to form a loop on the face or the back, depending on the weave^[3].

Pile height is set mainly by the loose-pick distance together with the pile warp let-off. Depending on the machine, the loose pick is created by shifting the reed or by moving the cloth fell back and forth. Electronically controlled terry looms can program pile height along the towel without stopping; one current loom generation offers settings from zero to twelve millimetres^[4]. This is how a single towel combines a looped body, a flat woven border and a band with a different pile height.

Three-pick terry is the standard construction for bath and hotel towels. Two-pick terry has largely disappeared because its loops are unstable. Four-pick terry adds a further pick to each group, so each loop is bound by more weft and fewer loops are formed per centimetre of length; it is woven far less often, partly because the beat-up sequence is more complex^[3]. Constructions with more picks are used for special effects. Anchorage matters in use: loops that are weakly bound are pulled out by rings, hooks and abrasion, leaving snags and long pulled loops. Resistance to loop extraction can be measured with a dedicated European test method, EN 15598.

Pile density is the number of loops per unit area. It follows from the number of pile ends per centimetre across the width and the number of loops per centimetre along the length. Pile height, density, yarn count and the ratio of pile to ground yarn together determine the weight of the towel, its hand and how much water it can hold. Research on terry fabrics finds that the rate of water absorption rises with loop density and loop length^[5]. A tall, sparse pile feels soft at first but flattens and tangles; a shorter, denser pile is more stable, though it can feel firmer.

Single-sided terry carries loops on one face only and is used where one smoother face is wanted. Double-sided terry, with loops on both faces, is the normal bath towel. Patterns are woven in two ways. A dobby head controls a limited number of heald frames and weaves geometric borders, plain bands and simple patterns. A jacquard head controls warp ends individually or in small groups and can weave lettering, logos and pictorial designs, including tone-on-tone effects where pile and flat areas form the motif. In two-colour jacquard terry, pile ends of one colour are raised on one face and the other colour on the reverse, so the design appears on both faces in opposite colours.

Greige inspection

Fabric straight off the loom is called greige, or grey, goods. It is inspected before wet processing because faults become harder and more expensive to trace afterwards. Inspectors look for broken or missing ends, which leave lines without loops; weft faults such as thick places and double picks; uneven loop height; pulled or flattened loops; oil stains from the loom; and errors in border patterns. Width and weight per unit area are checked against the construction, since both drift when warp tensions or pick density are wrong.

Desizing, scouring and bleaching

Raw cotton and sized yarn absorb water poorly. The size film on the ground warp and the waxes, pectins and proteins on the fibre surface repel water, so the first wet stages remove them. Desizing breaks down starch size, usually with amylase enzymes, or washes out water-soluble synthetic size. Scouring in a hot alkaline bath emulsifies the natural waxes and removes most remaining impurities; after it, cotton wets almost instantly. Bleaching, most often with hydrogen peroxide under alkaline conditions, removes the natural yellowish colour to give a white towel or a clean base for bright and pale shades, and optical brighteners may be added for high-white hotel towels.

Modern dyehouses often combine these steps to save water and energy, but each must still be rinsed out thoroughly. Residual alkali, peroxide or size interferes with dyeing, can yellow the towel in storage and weakens the fibre.

Dyeing cotton towels

Towels are coloured either as yarn or as fabric. Yarn dyeing, on packages or beams, is needed for stripes, checks and two-colour jacquards, where different ends must carry different colours. Piece dyeing colours woven fabric or finished towels in batches, usually in winch or jet machines that move the fabric gently through the dye liquor so the loops are not crushed.

Reactive dyes are the main dye class for cotton towels. Salt drives the dye onto the fibre, and alkali then makes it react with the hydroxyl groups of cellulose to form a covalent bond^[6]. Because the colour is chemically bound, a well-dyed reactive shade withstands washing. Part of the dye, however, reacts with water instead of the fibre. This hydrolysed dye has no bond and must be removed by a sequence of hot rinses and soaping baths. If the wash-off is incomplete, loose dye bleeds in the first domestic washes and stains other items, a common cause of failed washing-fastness tests. The fabric is then neutralised to a near-neutral pH, which matters for skin contact and for the finishing chemicals applied next.

Finishing: the balance between softness and absorbency

After wet processing the loops are tangled and the hand can feel dry and harsh. Finishing corrects this chemically and mechanically. Softeners lubricate the fibres so the loops slide and feel smooth. Cationic softeners, the basis of most conventional softening agents, coat the fibres with a fatty layer that makes the surface more hydrophobic, and research on terry fabrics consistently finds that softeners reduce water uptake while plain washing and tumbling increase it^[5]. Hydrophilic softeners and careful dosing are used to balance hand and absorbency. This is why a towel that feels exceptionally silky on the shelf can absorb less in its first uses than one with a drier hand, and why absorbency often improves over the first launderings as the finish is washed out.

Mechanical finishing includes batch tumbling, which opens and fluffs the loops; shearing, which cuts the loop tips on one face to make velour; and, less often, brushing. Velour has a smooth, even surface that shows woven and printed designs clearly, but cut pile has been found to be less hydrophilic than uncut loops^[5], so a velour face absorbs less than the same towel left in loop terry.

Drying, dimensional stability and shrinkage control

Cotton shrinks in washing as tension stored during weaving and wet processing relaxes, and terry adds its own movement because loops contract as they swell. Towel fabric is therefore dried in a relaxed state, in tumble or relax dryers, or on a stenter with overfeed rather than stretched flat to width. A fabric pulled out to size stores shrinkage that appears in the customer’s first wash. Residual shrinkage is measured by marking the fabric, washing and drying it by a standard domestic procedure and measuring it again, as described in ISO 5077 and ISO 6330. Shrinkage that differs between the pile body and the flat border produces wavy borders and puckered hems, a visible fault on hotel towels.

Cutting, hemming and border construction

Towels are usually woven as a continuous length, with a flat band at each towel end built into the pattern. Cross-cutting separates the towels through these bands, and wide fabric woven several towels across is long-cut between them. Side edges are finished either as woven selvedges or with overedge stitching, and the cut ends are folded and stitched into hems. Hanging loops, care labels and brand labels are sewn in at this stage.

Hems are a frequent point of failure on hospitality towels, because industrial laundering combines high temperature, strong mechanical action and repeated tumble drying. Stitch density, sewing thread and hem width should therefore be part of the specification rather than left to default, and the hem should lie flat after washing, not ripple against the towel body.

Embroidery and other customization

Embroidery is applied to finished towels or cut panels with a stabilising backing, often with a soluble topping that stops the stitches sinking into the pile. A woven jacquard logo is part of the cloth itself, while a printed logo on cotton uses reactive or pigment printing. The choice depends on quantity, the look required and how the towel will be laundered.

Final inspection, folding and packing

Finished towels are inspected piece by piece or by statistical sampling, commonly using acceptance quality limit (AQL) sampling plans such as those in ISO 2859-1. Checks cover size, weight, shade against the approved standard, hems and seams, pulled loops, stains and labelling. Weight is checked because it is a commercial specification: a towel that is lighter than agreed contains less yarn. Towels are then folded to the agreed format, labelled, bundled or individually packed, and packed into marked export cartons.

Reading a terry towel specification

A towel specification combines a few figures that are easy to compare and several that are not. The most common terms mean the following.

GSM

Mass per unit area of the finished towel in grams per square metre. It measures how much material a towel contains, not how good it is. A heavier towel holds more water in total and feels denser, but studies report that weight has little effect on how quickly a terry fabric absorbs, and lighter fabrics take up more water per gram^[5]. A heavier towel also has more water to dry out and costs more to launder, so for gym, beach and kitchen use a lighter towel is often the better specification. Choosing the weight.

Yarn count

The fineness of pile, ground and weft yarns, usually in Ne (cotton count). Ply is written after the count: Ne 16/2 means two Ne 16 yarns twisted together.

Pile height

The height of the loops above the ground cloth, normally given in millimetres. With density, it determines softness, water capacity and how quickly the towel dries.

Picks per loop

Three-pick or four-pick terry. More picks per loop bind each loop with more weft and give fewer loops per centimetre of length.

Pile-to-ground ratio

How much pile warp the fabric consumes relative to ground warp, usually stated as a length ratio and sometimes as the pile share of fabric weight; the specification should say which (pile ratio). A higher share of pile generally means more absorbent surface; very high ratios need a strong ground to keep loops anchored.

Fibre composition

Given separately for pile, ground and weft where they differ. A towel with a cotton pile on a cotton-polyester ground is not a 100% cotton towel.