VAT DYES: See DYES.
V-BED FLAT-KNITTING MACHINE: A latch-needle weft-knitting machine with two needlebeds at a 90° angle to each other in the form of an inverted V. Each needlebed is at a 45° angle to the horizontal. These machines are used primarily to produce collars, sleeves, sweater strips, and rib trims.
VEGETABLE FIBER: A textile fiber of vegetable origin, such as cotton, kapok, jute, ramie, and flax.
VELOUR: 1. Generally, a soft, closely woven fabric with a short, thick pile, weighting about 10 to 20 ounces per yard and made in a plain or satin weave. Velour is usually made of cotton or wool, or with a cotton warp in wool, silk, or mohair velour. It is also made in blends of spun manufactured fiber and wool. Velours are used for coats, draperies, upholstery, powder puffs, and other pile items. 2. A felt with velvet-like texture used for men’s and women’s hats.
VELVET CARPET: A woven carpet in which the pile ends are lifted over wires that are inserted in the same manner as the filling and that cut the pile as they are withdrawn.
VELVETEEN: A fabric with a low filling pile made by cutting an extra set of filling yarns woven in a float formation and bound to the back of the material at intervals by weaving over and under one or more warp ends.
VELVET FABRIC: A warp-pile woven fabric with short, dense cut pile that produces a rich fabric appearance and soft texture. Two methods are used for weaving velvets. In the double-cloth method, two fabrics are woven face to face with the pile ends interlocking. A reciprocating knife cuts through these pile ends to produce two separate pieces of velvet. In the second method, pile ends are lifted over cutting wires that are inserted with the filling and that are withdrawn to cut the pile. Velvet is produced in a wide range of constructions and types. Originally made of silk, but now also of cotton or manufactured fibers giving fabrics that are sometimes washable. The fabric can be specially finished to make it crush-resistant and water-repellent or it may be embossed or patterned by burn-out printing.
VERTICAL FLAME TEST: See FLAMMABILITY TESTS.
VIBROSCOPE: An instrument for determining the mass per unit length of a fiber.
VINAL FIBER: A manufactured fiber in which the fiber-forming substance is any long chain synthetic polymer composed of at least 50% by weight of vinyl alcohol units and in which the total of the vinyl alcohol units and any one or more of the various acetal units is at least 85% byweight of the fiber (FTC definition). Vinal fibers show good chemical resistance but soften at comparatively low temperatures. Vinal fibers are used for apparel, industrial goods, and fishnets.
VINYL: A univalent radical, (CH2=CH-), derived from ethylene.
VINYLIDENE CHLORIDE: A chemical material obtained from ethylene, a petroleum product, and from chlorine. It is used for the manufacture of textile monofilaments and film. It is more commonly identified in the U.S. as saran. (Also see SARAN FIBER.)
VINYON FIBER: A manufactured fiber in which the fiber-forming substance is any long chain synthetic polymer composed of at least 85% by weight of vinyl chloride units (FTC definition).
VISCOMETER: A device designed to measure the viscosity (resistance to flow) of the fluid. Many types exist from simple calibrated glass tubes to extensively instrumented, on-line shear viscometers.
- One of the methods of producing rayon. (Also see RAYON FIBER).
- The chemical process used in the manufacture of cellophane. (Also see VISCOSE SOLUTION).
VISCOSE RAYON: One type of rayon. It is produced in far greater quantity than cuprammonium rayon, the other commercial type. (Also see RAYON FIBER.)
VISCOSE SOLUTION: The solution obtained by dissolving cellulose xanthate in caustic soda, from which viscose filaments and cellophane are produced.
VISCOSITY: The internal flow resistance of a fluid. (Also see INTRINSIC VISCOSITY and RELATIVE VISCOSITY.)
VOILE FABRIC: A sheer spun cloth that is lightweight and soft. It is usually made with cylindrical, combed yarn. Voile is used for blouses, children’s wear, draperies, bedspreads, etc.
VOLATILE: Readily vaporized at a relatively low temperature.
VOLATILITY: Property of having a low boiling point or temperature of sublimation at normal pressure. Likewise, having a high vapor pressure at ambient conditions.
VOLUME RESISTIVITY: The ration of the potential gradient parallel to the direction of current flow in a compound to the current density after a specified time of voltage application.
VULCANIZATION: See CURING, 2.