Textile Structure
how cloth is put together
Concept

Water — where it appears

Liquid water in a fabric, which is held in three places at once. It sits in the fibre's own substance as regain, in the channels between the fibres of a yarn and in the holes between the yarns, filling and draining in an order the pore sizes fix; the fibre's share is smallest.

Named by 5 essays across one field — each of them below, with the objects they name alongside it.

One canopy, two opposite outcomes, decided by a sign. What a canopy does to a drop, for sheeting raised 32-fold. A rough surface multiplies the cosine of the intrinsic contact angle by its roughness ratio, which here is 2.0 — a hair is a cylinder and contributes πd of surface for every d of shadow. So a fibre that wets at all is driven to complete spreading, and one that does not is driven to a Cassie state sitting on 32.4% solid and air. The dashed diagonal is what the bare fibre would do; the canopy pushes every point away from ninety degrees, in whichever direction it already lay. Raising is therefore not a wetting treatment or a repellency treatment — it is an amplifier, and which one it turns out to be was settled by the chemistry before the raising machine was switched on. What the figure cannot show is which state a real drop reaches, because both are available near the hinge and the one it finds depends on how it arrived.

The hairs decide the sign of the wetting

Raising a cloth is not a wetting treatment and it is not a repellency treatment. It is an amplifier, and which of the two it turns out to be was settled in the dyehouse before the raising machine was switched on — by whether the fibre's own contact angle was above or below ninety degrees.

cloth · Water Where a wet cloth keeps its water. For four cloths of this collection's own table, the share of the water a saturated cloth holds that sits inside the fibre as regain, between the fibres inside the yarn, and between the yarns in the cloth's own holes. muslin at 99 grams a square metre holds 183 per cent of its own weight, 4.6 per cent of it in the fibre; sheeting at 155 grams a square metre holds 113 per cent of its own weight, 7.5 per cent of it in the fibre; poplin at 100 grams a square metre holds 165 per cent of its own weight, 5.2 per cent of it in the fibre; duck at 207 grams a square metre holds 139 per cent of its own weight, 6.1 per cent of it in the fibre. The fibre's own water — the property cotton is sold on — is a twentieth to a thirteenth of the total, and the other nineteen twentieths are geometry. What the bars cannot show is the hair layer, which holds water outside all three of these and which this arithmetic has no place for.

A cotton's own water is a twentieth of what a cloth holds

A wet cloth keeps water in three places and only one of them is the fibre. A sheeting saturated holds 113 per cent of its own dry weight: 7.5 per cent of that inside the cotton as regain, 39 per cent in the channels between the fibres of its yarns, and 54 per cent in the holes four threads bound. The same construction in polyester, whose regain is a fortieth of cotton's, holds 105 per cent — an eight-point difference from a fortyfold one, because absorbency is a geometry with a fibre in it rather than a fibre with a geometry round it.

cloth · Water The suction water supplies, against the pressure twist supplies. The pressure pressing a yarn's fibres together, against its twist, with the suction inside the menisci of a damp yarn's own pores drawn as a level. The suction is 0.0624 newtons a square millimetre — 2γ over the pore radius of 2.3 micrometres — and it does not depend on the twist at all. The twist's pressure crosses it at about 186 turns a metre, so water is worth as much as the first 186 turns and nothing more: at 600 turns it is 11 per cent of what the twist already supplies. What the chart cannot show is the saturation, at which the suction vanishes because a full yarn has no meniscus in it.

A wet fibre is stiffer and a wet yarn is not locked

The intuitive reason a damp cloth stiffens is that water pulls the fibres together — a meniscus is curved, the pressure inside it is below atmospheric, and the suction presses the assembly exactly as twist does. Computed, that suction is worth the first 186 turns a metre of twist and nothing after them: six per cent of what an ordinary yarn's twist already supplies, and nowhere near enough to stop the fibres sliding. What wetting actually does is fatten the fibres, and a fibre's bending rigidity goes as the fourth power of its diameter — so a wet cotton fibre is 2.07 times as stiff with no contact in the argument at all.

cloth · Water What a spin leaves in a cotton load, against the drum's speed. The water left in a 68 mm load of cotton sheeting in a drum of 250 mm radius, as a share of the load's dry weight, against the spin speed. Read with the fibre holding its swollen water, the spin leaves 51% at 1,000 rpm and 41% at 1,400, and no speed takes it below 30%, the volume the fibre grew by. Read with the fibre holding only its regain, as the earlier account of a wet cloth did, the same spin leaves 16% at 1,400 and the floor is 8.5%. What the chart cannot show is the water a drained channel keeps as a film and as rings at the fibre contacts, which the model takes as nothing and which lifts every point on both curves.

A spin leaves the water a fibre swelled by

A washing machine's spin is a centrifuge, and it drains a cloth in the order its pores give up water: the holes between the yarns at a few g, the channels inside the yarns only far enough from the drum's wall, and the water inside the fibre never. That last reservoir is not the regain. A soaked cotton fibre holds the volume it swelled by — 30 per cent of its dry weight, three and a half times the regain — and it is the floor under every spin speed there is.

cloth · Water What every 150 g/m² cotton cloth carries into the drying, against its count. The water a plain cotton cloth of 150 grams a square metre holds when it starts to dry, as a share of its dry weight, for every count that can make that weight as one cloth, from 20 to 200 tex — cloths whose thickness runs from 0.33 to 1.06 mm. Laid flat without a spin, every pore is full and the share climbs with the count from 128% to 591%, because a coarser cloth of one weight has larger, deeper holes. Hung on a line for a metre, the holes drain above their own head and every count keeps 101% to 104%. Spun at 1,400 rpm in a full load, every count keeps 40.9%, the finest and the coarsest within 0.1 of a point of each other. What the chart cannot show is the water a drained channel keeps as films, which lifts the two lower lines alike.

A spun cloth dries by its weight

Every plain cotton of 150 grams a square metre contains the same fibre, and the count only arranges it: the coarsest is three times as thick as the finest. Laid out wet without a spin, the thick one holds four and a half times as much water, all of it in its holes. Spun, every one of them keeps 40.9 per cent of its weight and dries in the same time — because a spin empties the holes, and what it leaves in the yarns is not their volume but the fibres' surface, which the weight has already fixed.

cloth · Water

Named alongside it

The objects these essays reach for when they reach for this one.

MoisturePacking factorSwellingTwo pore systemsOpen areaRegainWickingAreal weightBending rigidityCanopy criterionCassie stateContact angle

All concepts