Woven Fabric

an article produced by weaving, that is, by the interlacing of perpendicular threads—longitudinal (warp) and transverse (weft). In certain cases, additional systems of threads may be used to form a nap or patterns. Woven fabrics are the most common textiles; they may be produced as cloth or finished goods, such as kerchiefs or tablecloths. Woven fabrics are thin (usually less than 5 mm), wide (usually up to 1.5 m and sometimes up to 12 m), and of varying length. Lengths of fabric supplied for commercial use are called pieces and are usually 20–40 m long. Narrow strips less than 0.4 m wide are also produced.

Classification of woven fabrics. Woven fabrics are classified by fiber composition and purpose, as well as by the methods used in production, finishing, and dyeing.

Woven fabrics are produced from virtually all types of textile fibers and threads. Depending on the sector of the textile industry producing the fabric and the principal fiber composition, they may be classified as cotton, linen, wool, silk, or other fabric. Silk fabrics may be produced from man-made fibers or natural silk. Woven fabrics may be manufactured from a single type of fiber or thread or with a mixture of not more than 10 percent of another type; from a blend of threads obtained from several types of fibers; or from an alternation of various types of threads. Depending on their purpose, woven fabrics may be classified as domestic or industrial. Domestic fabrics account for approximately two-thirds of the total quantity of fabrics produced; they are subdivided into apparel fabrics—for undergarments, dresses, suits, and kerchiefs; decorative fabrics—for upholstery and drapes; and moisture-absorbing fabrics—for towels and napkins. The textile industry considers fabrics produced in large quantities, such as calico and satin, as separate groups.

The majority of domestic fabrics are made from cotton. Silk and linen are second and third in production volume. Wool fabrics may be produced from worsted yarn—a fine, smooth (combed) yarn—for making dresses, suits, and overcoats; from thicker (condensed) yarn for overcoats and suits; or from the coarsest, thickest condensed yarn for making overcoats and blankets.

The terms “loom state” and “gray goods” are applied to unfinished fabrics that have been removed from the loom. Yarn-dyed fabrics are produced from threads of various colors; melange fabrics are obtained from yarn made from a mixture of fibers of different colors. In addition to a smooth surface, fabrics may also have a fleecy external layer, or nap. Pile fabrics have a nap, either looped or cut, that is formed by an additional system of threads; in napped fabrics, the nap is formed from the filling. Felts have a face that is so compacted as a result of fulling that the weave is concealed. Thickened threads may be used to form ribs on the surface of fabrics; patterns in relief may also be produced (seeJACQUARD ATTACHMENT). Multiple fabrics are produced from several superimposed warps and are held together by common weft threads.

Before fabrics are delivered to a consumer, they are usually subjected to bleaching, dyeing or printing (seePRINTING), and various types of final finishing processes. Uniformly dyed fabrics are dyed with a single color; printed fabrics have a pattern printed on one side.

In the USSR individual types of fabrics, differing from one another in even one characteristic, such as thickness of the threads, number of threads per unit length or width, or weaving pattern, are designated by an identifying code number. The USSR produces approximately 4,000 individual types of fabrics.

Primary characteristics and properties of woven fabrics. The structure of a woven fabric is characterized by the thickness of the threads (judged by thread density, that is, by the weight in grams of 1 km of thread), by the type of interlacing of threads, by the density of the weave, by the ratio of the flexure of the warp and weft threads, and by the surface structure (smooth or napped). The properties and appearance of a woven fabric are determined by the fabric’s structure, by the properties of the threads, and by the finishing.

In the USSR woven fabrics are certified according to three quality categories: superior, first, and second. Fabrics that have been awarded the state seal of quality are in the superior quality category; fabrics that have been classified as of second quality are taken out of production. Production method, structure, and final finishing are taken into account when a fabric is assigned to a quality category, as are such indicators as density (the weight of 1 sq m of fabric), shrinkage, color fastness, whiteness, wearability, pilling, resistance to wrinkling, and other mechanical properties.

Density characterizes the amount of material used in the manufacture of the fabric and, indirectly, the fabric’s thickness. It varies from 30 gm per sq m for silk chiffon crepe to 1,000 gm per sq m for canvas and belting. The density of the most widely used dress fabrics, such as calico and satin, is 90–150 gm per sq m, and for wool suiting 250–400 gm per sq m. The shrinkage of a woven fabric indicates the reduction in size, expressed in percent of the initial value, after washing, drying, dry cleaning, and storage. Acceptable values are 1.5–5 percent for warp shrinkage and 1.5–3.5 percent for weft shrinkage. The color fastness of a fabric is tested for exposure to light, weathering (joint exposure to light and atmospheric conditions), washing, and friction. Color fastness is judged visually by means of comparisons of the test samples with standard samples. The highest rating is 8 for exposure to light and to weathering and 5 for other exposures. The whiteness of a fabric is measured on a photometer.

A fabric’s wearability—its ability to withstand abrasion, washing, dry cleaning, weathering and other effects—is determined from experimental wearing of clothing made from the fabric; it is also measured on instruments that simulate normal wear. Wear-ability is evaluated on the basis of any reduction in strength, durability, and weight, as well as any change in the viscosity of a solution obtained by dissolving the fabric in an alkali or acid. Resistance to abrasion is characterized by the number of use cycles that cause destruction of the fabric. Abrasion may cause small balls, or pills, to form on the surface of a fabric from the rolled ends of fibers. Fabrics containing synthetic fibers are particularly prone to pilling. The coefficient of resistance to wrinkling is determined from the recovery angle of a fabric sample bent 180° or from the change in the dimensions of an artificially pressed fold.

In order to assess the mechanical properties of a woven fabric, the fabric’s strength and elongation under stretching are usually measured until the breaking point is reached; fabric fatigue and other properties are also evaluated. Breaking loads vary from 50 newtons per 50 mm for gauze to 3,500 newtons per 50 mm for canvas and belting; calico has a breaking load of 250–400 newtons per 50 mm, and wool suiting 350–600 newtons per 50 mm. Elongation is expressed as the difference between the fabric’s final and initial lengths, in percent.

Evaluation of the hygienic qualities of woven fabrics includes determination of the ability to absorb water and water vapor; capillarity; permeability to air, water, and steam; heat conductivity; and, more rarely, ability to hold an electric charge.