Pile,Terry,Leno
and
Triaxial Weaves
Luxurious velvets with downlike textures, elaborate brocades with intricate woven-in designs, small geometrical patterns, and cobwebby lace effects are quite impossible to make on the plain harness loom These fancy effects call for either special looms or attachments for the regular harness loom; the actual weaving is usually slower than standard weaving; and the price of these elaborate effects is higher than that of the plain weaves. Nevertheless, these fabrics are in demand; they are attractive and often are used in high style fashion goods.
1 Pile Fabrics
A definition of the term 'pile' is: 'A surface effect on a fabric formed by tufts or loops of yarn, introduced into the fabric for the purpose, which stand up from the body of the cloth.' Attention must be drawn to the distinction between the terms 'pile' and 'nap'. Whereas a 'pile' is produced by weaving, a 'nap' is developed on the fabric surface during cloth finishing processes such as brushing and raising. Usually the fibers are teased out of the fabric by the action of fine wire teeth, by teasels, or by carborundum as in raiding. A nap or suede effect can also be produced by flock printing.
Pile fabrics can be produced by weaving, knitting, or tufting. Here we are concerned with woven pile fabric, which may be classified in the following way:
Warp pile: cut loops; (velvet)
uncut or loop pile; (terry towelling)
Weft pile: cut; (velveteen and corduroy)
Ø VELVET
The uniform dense pile is produced by cutting warp yarns which have been specially woven in to from the pile. There are three principal methods of weaving velvet, two of which involve lifting the pile warp over wires or metal strips, which determine the height of the pile. The pile is cut at the loom by different techniques. The third method is to weave two cloths face to face, as shown in Figure 12.1, with the pile warp alternating between the upper and lower fabrics. At the front of the loom a knife moves back and forth across the width of the cloth and cuts the pile warp as the cloth moves forward during weaving. In this way two separate pieces of velvet are produced simultaneously.
The bloom and attractive appearance of velvet is developed after dyeing during fabric finishing when the pile is cut level by cropping or shearing. Then, by brushing and the use of steam, the fibers in the cut yarns are splayed out and are made either to stand erect or are laid at an angle. A variety of velvets made from various fibers are in styles such as Brocaded, Genoa, and Nacre
Ø TERRY
This cloth consists of a loop-pile and is sometimes known as 'Turkish towelling'. The method of manufacture differs from that for velvet because here no wires are used. During weaving the reed beats forward completely only on every third pick and, consequently, three picks are carried forward at the same time, thus causing the pile-warp, which is slack, to loop above and below the fabric to form the pile. The loops are anchored in position by the interlacing of the weft yarn and the firmly woven ground-warp. See Figure 12.2.
Ø . VELVETEEN
The pile in velveteen is short and uniformly dense and is produced after weaving by cutting the pile-weft, which floats on the surface of the cloth. Velveteen is commonly made from cotton and requires brushing and cropping to develop the lustre and uniformity of pile. After dyeing, in order to obtain a rich bloom a solution of dye is applied to the pile, and revolving brushes spread the dye on the surface. In fact, frequent brushing of the pile is an essential feature of the finishing of such cloths. Figure12.3 shows a cross-section of a velveteen.
Ø CORDUROY
Corduroy is sometimes known, as corded velveteen. The distribution of the pile is such that the floats of the pile-weft yarn lie in rows down the length of the cloth, as shown in Figure 12.4. When the weft is cut the pile forms lines or cords, which run in the warp direction. For satisfactory wear it is important for the pile to be firmly anchored in the ground structure. It is peerage to have the tufts held in place by only one warp thread, as illustrated， with the result that the tuft forming the pile is V-shaped. A much firmer structure is achieved by having W－shaped tufts. The back of pile fabrics is sometimes lightly raised or sized to improve the fastness of the pile.
2 Method of Pile Weaves
Cloths with soft, downy textures are velvets, velours, and plushes. All three of these fabrics are made in pile weave. The right side of these cloths consists of soft, clipped yarns, called pile. The wrong side of the fabric is smooth, with no pile and with the weave showing distinctly.
Pile weave is not an entirely new construction, for it uses the plain or twill weave as its base. Twill is the stronger of the bases. The back of the fabric indicates the basic weave. But the soft pile made from extra yarns is the novelty. The extra set of yarn may be warp or filling. There are four methods of weaving pile fabrics. These are discussed below.
2.1 The Wire Method
Good-quality velvets, plushes, and Wilton and Axminster rugs are made with extra warp to form the pile. One set of warps interlaces with the filling to form the plain- or twill-weave ground of the fabric; the other set of warps forms the pile. When a row of pile is made, the warp yarns to form the pile are first raised by the harness to form the shed. Then a wire is inserted through the shed, much as filling yarn is shot through. The size of this wire is determined by the size of the pile to be made. When the set of warps to form the pile is lowered, it loops over the wire and is held in place by the next filling. The wire is then withdrawn. As this is done, a small, sharp knife attached to the end of the wire cuts the pile warp loops. The ground is then woven for a certain number of picks; then the wire is again inserted to form the pile. If the pile has not been cut evenly by the wires, the fabric is sheared again with a device like a lawn mower. (See Figure. 12.5)
Sometimes the pile is left uncut: a wire with no knife is used, or a number of filling threads are substituted for the wire and are then withdrawn. Frieze used for upholstery is usually made with uncut loops.
2.2 The Terry Weave or Slack-Tension Pile Method
A less expensive method of pile weaving omits the wire. Groups of warps are held in tension for the groundwork of the fabric. The warps that form the pile has their tension released at intervals and are thus shoved forward. The tension is restored, and the battening up of the filling causes these warps to appear in loops. The easiest way to make this construction is to use four harnesses, two for the slack pile warps and two for the tight ground warps. On the first shed, pile warps are raised; two fillings are shot through this shed, but are not battened by the reed. The pile warps are lowered, and a third filling is shot through to interlace with the ground warps. Then all three fillings are battened back. Because the tension on the pile warps is loose when the fillings are battened, the pile warps appear in loops. This is known as a three-pick terry cloth because two picks go under the looped pile and one pick goes between two rows of pile. Figure 12.6 shows the ground of terry with pile removed.
The pile is usually on both sides of the fabric (pile yarns alternate in forming loops on the face and the back of the cloth). However, the pile may be made only on one side to form stripes or designs. Turkish towels are woven in this manner. Instead of "pile weave," the name "terry weave" should be used when referring to turkish toweling.
Terry weave is used to make Turkish towels, terry cloth, some friezes, and shagbark gingham. There is no nap to terry weave fabric due to the fabric structure. Uncut loops make the surface absorbent. Sheared terry is less absorbent.
2.3 The Filling Pile Method
To make corduroy, velveteen, and some plushes, extra fillings are floated over four or five warps. (See Figure 12.7.) The floats are cut after weaving, and then the cut ends are brushed up to form the pile. These floats require precision cuting in the center of the float by a special device equipped with knives. In corduroy, characterized by a pile stripe or wale alternating with a plain wale (no pile), a separate cutting knife is necessary for cutting the floats of each wale. If there are five wales to the inch in a wide-wale corduroy 40 inches wide, then twenty cutting knives would be required. A wide-wale cloth can have all the wales cut in one operation. Very narrow wale,
,called pinwale, would have sixteen to twenty-three wales to the inch. Pinwales are fed through the cutting machine twice. Velveteen and filling plush have an all-over pile construction. This is achieved by random floats over the face of the fabric rather than floats placed in rows as in corduroy. A twill-back velveteen is more durable than a plain back. Another point in durability is the way in which the pile is held to the ground. If a pile loop is pulled from the fabric, its shape will be a V or a W. A V reveals that the pile filling has interlaced with only one warp yarn, whereas a W reveals an interlacement with three warps. W is more durable because it is held to the ground by three warps instead of one.
2.4 The Double-Weave Method
Many average-grade millinery and transparent velvets are woven double; that is, two cloths are woven at the same time, face to face. Two sets of warps and two sets of fillings are used, and an extra set of warps binds the two cloths together. The plain, rib, twill, or satin weave may be used as the ground. The effect is not unlike a sandwich, with the extra set of binding warps corresponding to the jam inside. When the cloth is woven, a knife in the loom cuts the binding yarns, making two separate fabrics with sheared pile surfaces. Velvet, velour, plush and fake fur may be woven and cut apart.
2.5 Other Methods of Achieving Pile Construction
A pile fabric may be achieved by methods other than weaving. Pile can be structured in a fabric by hooking or tufting into an already structured fabric, flocking onto an already structured fabric as a finishing process, or produced by the use of pile yarns such as chenille. These methods are discussed in later
chapters.
3 Other Knowledge about Pile Weave Fabrics
3.1 Labeling Pile Fabrics of Fur Fibers and Man-Made Fibers
Real fur, fur blended with cellulose, nylon, acrylic, or modacrylic imitation fur may be used as pile. The back may be the same fiber content as the pile or a different fiber content. According to the TFPIA, the fiber content of pile fabrics, excluding rugs, must be labeled in percentages of fibers as they appear in the fabric by weight. Or, if desired, the pile may be stated separately, and the ratio between the pile and the back or base must be stated. In the finishing process, the pile can be printed to resemble leopard, for instance; or it can be processed to look like broadtail or ermine; or it can be sheared to resemble other furs. Sometimes the pile is curled to resemble Persian lamb. But the TFPIA has specified that textile fiber products may not employ any name directly or indirectly of furbearing animals, such as mink, mutation, and broadtail.
3.2 Identification of Warp and Filling
Velvets have extra warps for forming the pile. Velvet was originally made of the filament fiber, silk, and subsequently of other filament fibers such as rayon and nylon. Some upholstery velvets are made of cotton and linen.
To identify warp and filling, fold the fabrics first one way and then the other. The direction that shows distinct rows of pile is the filling direction. To check for accuracy, a yarn can be unraveled in each direction. One yarn looks like a caterpillar because the pile is clinging to it. Since extra warps make the pile in the fabrics mentioned, the filling yarn holds the pile and resembles the caterpillar. The pile does not adhere to the warp yarns.
In cotton velvet, velveteen, and some plushes, extra fillings make the pile. When yarns are unraveled both ways, one yarn holds the pile; this caterpillarlike yarn is the warp. The filling yarn will be smooth. Folding the fabrics shows distinct rows of pile lengthwise because extra fillings form the pile. No folding is required to identify the warp of corduroy. The wales run warpwise.
In terry weave with uncut pile, the best way to identify the warp is to pull a loop. Notice the direction from which it pulls. Since extra warps form the loop pile, the direction from which the loop pulls is the warp. A selvage always eliminates any complicated methods of identifying warp and filling.
3.3 Guides to the Buyer of Pile Fabrics
If pile construction is used for silk, man-made fibers, or fur, these textiles are presented to the consumer in their richest, most luxurious textures. Pile fabrics feel soft and downy. Silk pile takes a rich, deep color, especially when one looks directly into the pile. If the pile is pressed down, the fabric takes on a silvery,
satin cast.
Pile fabrics are warm and hence are best used for fall and winter wear. Transparent velvet with a long pile and loosely woven back is not so warm as a fabric with a short pile and a tightly woven back. An all-silk velvet is warmer than a silk with a cotton back or rayon pile. Nylon pile is very resilient, resists waterborne stains, and is easily maintained.
For velvet dresses, dressmakers usually cut the fabric so that the pile runs up. The wearer then can appreciate the richness of the fabric by looking into the pile. Another reason for having the pile run up is that the pile is less likely to mat from friction. Velvet drapes well, especially when it is all silk, and looks effective in both tailored and feminine lines. Cotton velvet is stiffer and because of its bulkiness is generally more appropriate for sportswear than for lightweight dresses. Velvets and corduroys can be made spot-resistant and of durable press. Corduroys are frequently made water-repellent for raincoats. And there are some washable velvets.