Textile Glossary - L

LACE: Ornamental openwork fabric, made in a variety of designs by intricate manipulation of the fiber by machine or by hand.

LACE STITCH: In this knitting stitch structure, loops are transferred from the needles on which they are made to adjacent needles to create a fabric with an open or a raised effect.

LAID-IN FABRIC: A knit fabric in which an effect yarn is tucked in, not knitted into, the fabric structure. The laid-in yarns are held in position by the knitted yarns.

LAID-IN YARN: See AXIAL YARN.

LAMÉ: A fabric woven with flat metal threads, usually silver or gold, that form either the background or the pattern.

LAMINAR FLOW: Streamline flow in a viscous fluid, such as molten polymer, near a solid boundary.

LAMINATED FABRIC:

1. Fabric composed of a high-strength reinforcing scrim or base fabric between two plies of flexible thermoplastic film. Usually open scrims are used to permit the polymer to flow through the interstices and bond during calendering.
2. See BONDED FABRIC, 1.

LAP: A continuous, considerably compressed sheet of fibers that is rolled under pressure into a cylindrical package, usually weighing between 40 and 50 pounds. The lap is used to supply the card.


LAPPING: A term describing the movement of yarn guides between needles, at right angles to the needle bar, or laterally in relation to the needle bar, or laterally in relation to the needle bar during warp knitting.

LAP SPLITTING: A condition caused by a lap that will not unwind in carding in the same thickness as it was wound in picking. This splitting of the sheet of fiber can result in either a thicker or thinner sheet being fed into the card.

LASE: An acronym for load at specified elongation: the load required to produce a given elongation of a yarn or cord.

LASER: A device for producing an intense beam of coherent light. It is used for cutting, spectroscopy, photography, biomedical investigations, etc.

LASHED-IN FILLING: See PULLED-IN FILLING.

LASTRILE FIBER: A manufactured fiber in which the fiber-forming substance is a copolymer of acrylonitrile and a diene composed of at least 10% by weight, but not more than 50% by weight, of acrylonitrile [-CH2-CH(CN)-] units (FTC definition).

LATCH NEEDLE: One of the two types of knitting machine needles. The latch needle has a small terminal hook with a latch that pivots automatically in knitting to close the hook. The fabric loop is cast off. The latch then opens, allowing a new loop to be formed by the hook, and loop-forming and casting-off proceed simultaneously. (Also see SPRING NEEDLE.)

LATENT CRIMP: Crimp in fibers that can be developed by a specific treatment. Fibers are prepared specially to crimp when subjected to specific conditions, e.g., tumbling in a heated chamber or wet processing.

LATEX: A milky fluid found in certain cells of some families of seed plants. Latex is the raw material from which rubber is made.

LAWN: A light, thin cloth made of carded or combed yarns, this fabric is given a creaseresistant, crisp finish. Lawn is crisper than voile but not as crisp as organdy.

LCP: See LIQUID CRYSTAL POLYMER.

LEA:

1. One-seventh of an 840-yard cotton hank, i.e., 120 yards.
2. A standard skein with 80 revolutions of 1.5 yards each (total length of 120 yards). It is used for strength tests. A unit of measure, 300 yards, used to determine the yarn number of linen yarn. The number of leas in one pound is the yarn number.

LEACHING: The removal of any substance or dye from textiles by the percolating action of a suitable liquid.

LEA COUNT CONSTANT: See BREAK FACTOR.

LEADER MARK: See DECATING MARK.

LEA PRODUCT: See BREAK FACTOR.

LENO WEAVE: A weave in which the warp yarns are arranged in pairs with one twisted around the other between picks of filling yarn as in marquisette. This type of weave gives firmness and strength to an openweave fabric and prevents slippage and displacement of warp and filling yarns.

LET-OFF MOTION: A device for controlling the delivery and tension of the warp during weaving.

LEVELING: Migration leading to uniform distribution of dye in a dyed material. Leveling may be a property of the dye or it may require chemical assistance.

LEVEL LOOP: A term describing a tufted or woven carpet with uncut, equal length loops composing the pile surface.

LICKERIN: A part of the feed mechanism of the card. It consists of a hollow, metal roll with a spirally grooved surface containing a special saw-toothed wire. The lickerin opens up the tufts o the picker lap as it is fed to the card and transfers the fibers to the main cylinder.

LICKERIN LOADING: A condition whereby fibers are imbedded in the lickerin wire clothing so as to resist transfer to the cylinder clothing.

LIGHT END:

1. The low boiling fraction in distillation.
2. See FINE END, 1.

LIGHTFASTNESS: The degree of resistance of dyed textile materials to the color-destroying influence of sunlight. Two methods of testing are in use: (1) exposure to sunlight, either directly or under glass, and (2) accelerated testing in a laboratory apparatus equipped with any of several types of artificial light sources.

LIGNIN: The major noncarbohydrate portion of wood. It is an amorphous polymeric substance that cements the fibrous portions together.

LIMITING OXYGEN INDEX: A relative measure of flammability that is determined as follows. A sample is ignited in an oxygen/nitrogen atmosphere. The oxygen content is adjusted until the minimum required to sustain steady burning is found. The higher the value, the lower the flammability.

LINEAR DENSITY: Mass per unit length expressed as grams per centimeter, pounds per foot, or equivalent units. It is the quotient obtained by dividing the mass of a fiber or yarn by its length.

LINEN: Cellulosic fibers derived from the stem of the flax plant or a fabric made from these fibers. Linen fibers are much stronger and more lustrous that cotton; they yield cool, absorbent fabrics that wrinkle easily. Fabrics with linen-like texture and coolness but with good wrinkle resistance can be produced from manufactured fibers and blends.

LINEN LEA: The number of 300-yard hanks contained in one pound. 

LINET: A French-make lining fabric of unbleached linen.

LINING FABRIC: Fabric that is used to cover inner surfaces, especially when the inner surface is of a different material than the outer. May refer to garment lining, lining for boxes, coffins, etc. Generally of smooth, lustrous appearing fabrics, but also of felt and velvet. Both manufactured fibers and natural fibers are used.

LINK-AND-LINK: See PURL.

LINKED PROCESSES: Refers to the connection of the various steps of fiber-to-yarn processing via pneumatic fiber-transport systems, on-line monitoring, and process control. Process linking results in less labor-intensive processing. A typical linked system might include all stages from bale opening through carding.

LINON A JOUR: A gauze-like linen fabric used as dress goods.

LINT: Particles and short fibers that fall from a textile product during the stresses of use.

LINT BALL: See BALLING UP.

LINTERS: The short cotton fibers that are not removed from the seed during the first ginning. The linters are cut from the seed and used as a source for cellulose derivatives such as nitrocellulose or viscose rayon.

LIQUID CRYSTAL: A liquid in which the molecules are oriented parallel to each other resulting in birefringence and interference patterns visible in polarizing light.

LIQUID CRYSTAL POLYMER: Polymers such as aramids or the thermotropic polyesters that form liquid crystals when in the appropriate state, (concentrated solution or melt). Most liquid crystal polymers have in their structure a succession of para-ring structures. The liquid crystal formation is thought to relate to the fact that there is a limiting concentration of rod-like chains that can exist in a random arrangement in a solution or melt. Once this concentration is reached, ordering or alignment of the chains in necessary to accommodate them. Fibers from liquid crystal polymers generally have high modulus and tenacity, good chemical resistance, and hightemperature resistance. They are used in a wide range of applications including protective apparel, tire cord, composites, ropes and cables, etc.

LIQUOR RATIO: In wet processing the ratio of the weight of liquid used to the weight of goods treated.

LISLE YARN: A high-quality cotton yarn made by plying yarns spun from long combed staple. Lisle is singed to hive it a smooth finish.

LIVING RING: See REVOLVING SPINNING RING.

LOAD-DEFORMATION CURVE: A graphical representation of the relationship between the change in dimension (in the direction of the applied force) of the specimen resulting from the application of an external load, and the magnitude of that load. The load may be expressed in units of weight (such as pounds or kilograms) and the deformation in either units of length (such as inches or millimeters) in tension or compression tests, or degrees in shear tests. In a tension test, a load-deformation curve becomes a load-elongation curve.

LOAD-ELONGATION CURVE: See STRESS-STRAIN CURVE.

LOFT: The properties of firmness, resilience, and bulk of a fiber batting, yarn, fabric, or other textile material.

LONG STAPLE: A long fiber. In reference to cotton, long staple indicates a fiber length of not less that 1-1/8 inches. In reference to wool, the term indicates fiber 3 to 4 inches long suitable for combing.

LOOM: A machine for weaving fabric by interlacing a series of vertical, parallel threads (the warp) with a series of horizontal, parallel threads (the filling). The warp yarns from a beam pass through the heddles and reed, and the filling is shot through the “shed” of warp threads by means of a shuttle or other device and is settled in place by the reed and lay. The woven fabric is then wound on a cloth beam. The primary distinction between different types of looms is the manner of filling insertion (see WEFT INSERTION, 1). The principal elements of any type of loom areü the shedding, picking, and beating-up devices. In shedding, a path is formed for the filling by raising some warp threads while others are left down. Picking consists essentially of projecting the filling yarn from one side of the loom to the other. Beating-up forces the pick, that has just been left in the shed, up to the fell of the fabric. This is accomplished by the reed, which is brought forward with some force by the lay. (Also see JACQUARD.)

LOOM BARRÉ: A repeated unevenness in the fabric, usually running from selvage to selvage, and caused by uneven let-off or take-up or by a loose crank arm.

LOOM-FINISHED: A term describing fabric that is sold in the condition in which it comes from the loom.

LOOM FLY: Waste fibers that are inadvertently woven into a fabric.

LOOPED FILLING: A woven-in loop caused by the filling sloughing off the quill or by the shuttle rebounding in the box.

LOOPED PILE: A pile surface made of uncut looped yarns.

LOOPED YARN: See KINK.

LOOP ELONGATION: The maximum extension of a looped yarn at maximum load, expressed as a percentage of the original gauge length.

LOOPING: Generally, a method of uniting knit fabrics by joining two courses of loops on amachine called a looper. 

LOOPING BAR: A bar inserted in the bottom of an extrusion metier around which the dried filaments pass as they leave the spinning cabinet.

LOOP-KNOT: See KINK.

LOOP PILE: Carpet construction in which the tufts are formed into loops from the supply yarn.

LOOP TENACITY: The strength of a compound strand formed when one strand of yarn is looped through another strand, then broken. It is the breaking load in grams divided by twice the measured yarn denier or decitex. Loop tenacity, when compared with standard tenacity measurements, is an indication of the brittleness of a fiber.

LOOPY SELVAGE: A weaving defect at the selvage of excessive thickness or irregular filling loops that extend beyond the outside selvages.

LOOPY YARN: See TEXTURED YARNS.

LOOSE EDGE: See SLACK SELVAGE.

LOOSE END: See TIGHT or LOOSE END.

LOOSE FILLING: A fabric defect that is usually seen as short, loose places in the filling caused by too little tension on the yarn in the shuttle or by the shuttle rebounding in the box. Loose filling can often be felt by an examiner when passing a hand over the surface of the fabric.

LOOSE PICK: See SLACK PICK.

LOST END: An end on a section or tricot beam that has been broken at some stage in warping and has not been repaired by a knot.

LOT: A unit of production or a group of other units or packages that is taken for sampling or statistical examination, having one or more common properties and being readily separable from other similar units.

LOW ROWS: A carpet defect characterized by rows of unusually low pile height across the width of the goods.

LUANA: A fabric characterized by a crosswise rib effect, usually made with a filament yarn warp and a spun yarn filling.

LUBRICANT: An oil or emulsion finish applied to fibers to prevent damage during textile processing or to knitting yarns to make them more pliable. 

LUMINESCENCE: Emission of light not caused by incandescence but rather by physiological processes, chemical action, friction or electrical action. (See both FLUORESCENCE and PHOSPHORESCENCE.)

LUSTER: The quality of shining with reflected light. With reference to textile materials, the term is frequently associated with the adjectives bright or dull to distinguish between varieties of manufactured fibers.

LUSTERING: The finishing of yarn or fabric by means of heat, pressure, steam, friction, calendering, etc., to produce luster.

LYOCELL FIBER: A manufacturing cellulose fiber made by direct dissolution of wood pulp in an amine oxide solvent, N-methylmorpholine-N-oxide. The clear solution is extruded into a dilute aqueous solution of amine oxide, which precipitates the cellulose in the form of filaments. The fiber is then washed before it is dried and finished. The solvent spinning process for making lyocell fiber is considered to be environmentally friendly because the non-toxic spinning solvent is recovered, purified, and recycled as an integral part of the manufacturing process. No chemical intermediates are formed, the minimal waste in not hazardous, and energy consumption is low. Wood pulp is a renewable resource, and the fiber is biodegradable.

CHARACHTERISTICS: Lyocell fiber is stronger than other cellulosic fibers. It is inherently absorbent, having a water imbibition of 65%-75%. Lyocell retains 85% of its dry tenacity when wet, making it stronger when wet than cotton. The fiber has a density of 1.15 g/cm3.

END USES: Lyocell fiber is suitable for blending with cotton or other manufactured fibers. Because of its molecular structure, lyocell has the tendency to develop surface fibrils that can be beneficial in the manufacture of hydroentabled and other nonwovens, and in specialty papers. For apparel uses, the fiber’s unique fibrillation characteristic has enabled the development of fabrics with a soft luxurious hand. The degree of fibrillation is controlled by cellulose enzyme treatment.

LYOTROPIN POLYMER: Polymers that decompose before melting but that form liquid crystals in solution under appropriate condition. They can be extruded from high concentration dopes to give fibers of high modulus and orientation for use in advanced composites, tire cord, ballistic protective devices, etc.