Textile Glossary - D

DAMAGED SELVAGE: See CUT SELVAGE.

DAMASK: A firm, glossy, Jacquard-patterned fabric that may be made from linen, cotton, rayon, silk, or a combination of these with various manufactured fibers. Similar to brocade, but flatter and reversible, damask is used for napkins, tablecloths, draperies, and upholstery.

DAMPENING (IN TIRE CORD): The relative ability to absorb energy and deaden oscillation after excitation.

DECATING: See DECATIZING.

DECATING MARK: A crease mark or impression extending fillingwise across the fabric near the beginning or end of the piece.

DECATIZING: A finishing process in which fabric, wound tightly on a perforated roller, either has hot water circulated through it (wet decatizing), or has steam blown through it (dry decatizing). The process is aimed chiefly at improving the hand and removing wrinkles.

DECITEX: One tenth of a tex.

DECORTICATING: A mechanical process for separating the woody matter from the bast fiber of such plants as ramie and hemp.

DEEP-DYEING VARIANTS: Polymers that have been chemically modified to increase their dyeability. Fibers and fabrics made therefrom can be dyed to very heavy depth.

DEFECTS: A general term that refers to some flaw in a textile product that detracts from either performance or appearance properties.

DEFORMATION: A change in the shape of a specimen, e.g., an increase in length produced as the result of the application of a tensile load or force. Deformation may be immediate or delayed, and the latter may be recoverable or nonrecoverable.

DEGRADATION: The loss of desirable physical properties by a textile material as a result of some process or physical/chemical phenomenon.

DEGREE OF ESTERIFICATION: The extent to which the acid groups of terephthalic and/or other acids have reacted with diols to form ester groups in polyester polymer production.

DEGREE OF POLYMERIZATION: Refers to the number of monomer units in an average polymer. It can be controlled during processing and affects the properties of the end product.

DEGUMMING: The removal of gum from silk by boiling in a mildly alkaline solution. Usually accomplished on the knit or woven fabric.

DELAYED DEFORMATION: Deformation that is time-dependent and is exhibited by material subjected to a continuing load; creep. Delayed deformation may be recoverable following removal of the applied load.

DELUSTERING: Subduing or dulling the natural luster of a textile material by chemical or physical means. The term often refers to the use of titanium dioxide or other white pigments as delustrants in textile materials.

DELUSTRANT: A substance that can be used to dull the luster of a manufactured fiber. Often a pigment such as titanium dioxide.

DENIER: A weight-per-unit-length measure of any linear material. Officially, it is the number of unit weights of 0.05 grams per 450-meter length. This is numerically equal to the weight in grams of 9,000 meters of the material. Denier is a direct numbering system in which the lower numbers represent the finer sizes and the higher numbers the coarser sizes. In the U.S., the denier system is used for numbering filament yarns (except glass), manufactured fiber staple (but not spun yarns), and tow. In most countries outside the U.S., the denier system has been replaced by the tex system. The following denier terms are in use:

Denier per Filament (dpf): The denier of an individual continuous filament or an individual staple fiber if it were continuous. In filament yarns, it is the yarn denier divided by the number of filaments.

Yard Denier: The denier of a filament yarn. It is the product of the denier per filament and the number of filaments in the yarn.

Total Denier: The denier of a tow before it is crimped. It is the product of the denier per filament and the number of filaments in the tow. The total denier after crimping (called crimped total denier) is higher because of the resultant increase in weight per unit length.

DENIER VARIATION: Usually variation in diameter, or other cross-sectional dimension, along the length of a filament or bundle of filaments. It is caused by malfunction or lack of process control in fiber manufacturing and degrades resulting fabric appearance or performance.

DENIM: A firm 2 x 1 or 3 x 1 twill-weave fabric, often having a whitish tinge, obtained by using white filling yarns with colored warp yarns. Heavier weight denims, usually blue or brown, are used for dungarees, work clothes, and men’s and women’s sportswear. Lighter weight denims with softer finish are made in a variety of colors and patterns and are used for sportswear and draperies.

DENSITY: The mass per unit volume (usually expressed as grams per cubic centimeter). (Also see SPECIFIC GRAVITY.)

DENT: On a loom, the space between the wires of a reed.

DEREGISTERING (CRIMP): Process of disordering or disaligning the crimp in a tow band to produce bulk. (Also see THREADED-ROLL PROCESS.)

DESULFURIZING: An aftertreatment to remove sulfur from newly spun viscose rayon by passing the yarn through a sodium sulfide solution.

DETERGENT: A synthetic cleaning agent containing surfactants that do not precipitate in hard water and have the ability to emulsify oil and suspend dirt.

DEVELOPED DYES: See DYES.

DEVELOPING: A stage in dyeing or printing in which leuco compounds, dyes, or dye intermediates are converted to the final, stable state or shade.

DEWPOINT: The temperature at which a gas begins to condense as a liquid at a given pressure. Thus in air, it is the temperature at which the air becomes saturated when cooled with no further addition of moisture or change in pressure.

DIAGONAL (45°) FLAME TEST: See FLAMMABILITY TEST.

DIAL: In a circular-knitting machine, a circular steel plate with radially arranged slots for needles. A knitting machine equipped with both a dial and a cylinder (q.v.) can produce double-knit fabrics.

DIAMINE: A compound with two amino groups. Hexamethylenediamine, one of the intermediates in the manufacture of nylon 66 salt, is an example of this chemical type.

DIELECTRIC BREAKDOWN VOLTAGE: In an electrical insulating material, the voltage at which electrical breakdown occurs, i.e., the voltage at which current will flow and/or the material melts.

DIELECTRIC CONSTANT: Measure of the ability of a dielectric material to store electrical potential energy under the influence of an electric field, measured by the ratio of the capacitance of a condenser with the material as the dielectric to its capacitance with a vacuum as the dielectric.

DIELECTRIC STRENGTH: The average voltage gradient at which electrical failure or breakdown occurs. Expressed in volts per mil.

DIFFERENTIAL THERMAL ANALYSIS: A method of determining the temperature at which thermal events occur in a material undergoing continuous heating.

DIFFUSION: 1. A more or less gradual movement of molecules or ions through a solution or fiber as a result of the existence of a concentration gradient or repulsive or attractive forces. 2. The random movement of gas molecules.

DIMENSIONAL RESTORABILITY: The ability of a fabric to be returned to its original dimensions after laundering or dry cleaning, expressed in percent. For example, 2% dimensional restorability means that although a fabric may shrink more than this in washing, it can be restored to within 2% of its original dimensions by ordinary home pressing methods.

DIMENSIONAL STABILITY: The ability of textile material to maintain or return to its original geometric configuration.

DIMETHYL TEREPHTHALATE: [p-C6H4(COOCH3)2] An intermediate used in the production of polyethylene terephthalate, the polymer from which polyester fibers and resins are made.

DIMITY: A sheer, thin, spun cloth that sometimes has cords or stripes woven in. It is used for aprons, pinafores, and many types of dress goods.

DIP:

1. Immersion of a textile material in some processing liquid. The term is usually used in connection with a padding or slashing process. 
2. The rubber compound with which tire cords and other in-rubber textiles are treated to give improved adhesion to rubber.

DIP DYEING: See DYEING.

DIP PENETRATION: The degree of saturation through a tire cord after impregnation with an adhesive.

DIP PICKUP: The amount of adhesive applied to a tire cord by dipping, expressed as a percentage of the weight of the cord before dipping.

DIP TREATING: The process of passing fiber, cord, or fabric through an adhesive bath, followed by drying and heat-treating of the adhesive-coated fiber to obtain better adhesion.

DIRECT DYES: See DYES.

DIRECT ESTERIFICATION: In the production of polyethylene terephthalate, the process in which ethylene glycol is reacted with terephthalic acid to form bis-β-hydroxyethyl terephthalate monomer with the generation of water as a by-product.

DIRECTIONALLY ORIENTED FABRICS: Rigid fabric constructions containing inlaid warp or fill yarns held in place by a warp-knit structure. Used in geotextiles, coated fabrics, composites, etc.

DIRECTION OF TWIST: See TWIST, DIRECTION OF.

DIRECT PRINTING: See PRINTING.

DISCHARGE PRINTING: See PRINTING.

DISCOLORED PICK: See MIXED END or FILLING.

DISC TEST: An in-rubber test used to predict the fatigue resistance of tire cords and other industrial yarns.

DISPERSANT: A dispersing agent, often of a surface active chemical, that promotes formation of a dispersion or maintains a state of dispersion by preventing settling or aggregation.

DISPERSE DYES: See DYES.

DISPERSION:

1. A system consisting of finely divided particles and the medium in which they are distributed. 
2. Separation of light into colors by diffraction or refraction. 
3. A qualitative estimation of the separation and uniform distribution of fibers in the liquid during the production of a wet-formed nonwoven fabric.

DISTRIBUTION LENGTH: In fibers, a graphic or tabular presentation of the proportion or percentage (by number or by weight) of fibers having different lengths.

DIVIDED THREADLINE EXTRUSION: Spinning of two separate threadlines from one spinneret.

DOBBY:

1. A mechanical attachment on a loom. A dobby controls the harnesses to permit the weaving of geometric figures. 
2. A loom equipped with a dobby. 
3. A fabric woven on a dobby loom.

DOCTOR BLADE: A metal knife that cleans or scrapes the excess dye from engraved printing rollers, leaving dye paste only in the valleys of engraved areas. Also used to describe other blades that are used to apply materials evenly to rollers or fabrics.

DOCTOR STREAK: A defect in printed fabrics consisting of a wavy white or colored streak in the warp direction. It is caused by a damaged or improperly set doctor blade on the printing machine.

DOESKIN FINISH: A soft low nap that is brushed in one direction. Cloth with this type of finish is used on billiard tables and in men’s wear.

DOFF: A set of full bobbins produced by one machine (a roving frame, a spinning frame, or a manufactured filament-yarn extrusion machine).

DOFFER:

1. The last or delivery cylinder of the card from which the sheet of fibers is removed by the doffer comb. 
2. An operator who removes full bobbins, spools, containers, or other packages from a machine and replaces them with empty ones.

DOFFER COMB: A reciprocating comb, the teeth of which oscillate close to the card clothing of the doffer to strip the web of fibers from the card.

DOFFER LOADING: Fibers imbedded so deeply into the doffer wire clothing that the doffer comb cannot dislodge them to form a traveling web.

DOFFING: The operation of removing full packages, bobbins, spools, roving cans, caps, etc., from a machine and replacing them with empty ones.

DONEGAL: A tweed fabric with colorful slubs woven in, donegal is used for suits and coats.

DOPE: See SPINNING SOLUTION.

DOPE-DYED: See DYEING, Mass-Colored.

DOTTED SWISS: A sheer cotton or cotton blend fabric with small dot motif, dotted swiss is used for dress goods, curtains, baby clothes, etc.

DOUBLE BACK: A secondary backing glued to the back of carpet, usually to increase dimensional stability.

DOUBLE-CLOTH CONSTRUCTION: Two fabrics are woven in the loom at the same time, one fabric on top of the other, with binder threads holding the two fabrics together. The weave on the two fabrics can be different.

DOUBLE END: Two ends woven as one in a fabric. A double end may be intentional for fabric styling, or accidental, in which case a fabric defect results.

DOUBLE-KNIT FABRIC: A fabric produced on a circular-knitting machine equipped with two sets of latch needles situated at right angles to each other (dial and cylinder).

DOUBLE PICK: See MISPICK.

DOUBLE SELVAGE: See ROLLED SELVAGE.

DOUBLE WEAVE: A fabric woven with two systems of warp or filling threads so combined that only one is visible on either side. Cutting the yarns that hold the two cloths together yields two separate cutpile fabrics.

DOUBLING:

1. A process for combining several strands of sliver, roving, or yarn in yarn manufacturing. 
2. The process of twisting together two or more singles or plied yarns, i.e., plying.
3. A British term for twisting. 
4. The term doubling is sometimes used in a sense opposite to singling. This is unintentional plying. 
5. A yarn, considerably heavier that normal, produced by a broken end becoming attached to and twisting into another end.

DOUPPIONI: A rough or irregular yarn made of silk reeled from double or triple cocoons. Fabrics of douppioni have an irregular appearance with long, thin slubs. Douppioni-like yarns are now being spun from polyester and/or rayon staple.

DOWNDRAFT METIER: A dry-spinning machine in which the airflow within the drying cabinet is in the same direction as the yarn path (downward).

DOWNGRADE: In quality control, the lowering of the grade and/or value of a product due to the presence of defects.

DOWNTWISTER: A cap, ring, or flyer twisting frame.

DOWNTWISTING: A process for inserting twist into yarn in which the yarn passes downward from the supply package (a bobbin, cheese, or cone) to the revolving spindle. The package or packages of yarn to be twisted are positioned on the creel, and the ends of yarn are led downward through individual guides and stop motions to the positively driven feed roll and from there to the revolving take-up package or bobbin, which inserts twist.

DOWTHERM®: Trademark of Dow Chemical Company for a series of heat transfer media. Dowtherm jackets are used around molten polymer processing lines.

DRAFT: In weaving, a pattern or plan for drawing-in.

DRAFTING: See DRAWING, 1.

DRAFT RATIO: The ratio between the weight or length of fiber fed into various machines and that delivered from the machines in spun yarn manufacture. It represents the reduction in bulk and weight of stock, one of the most important principles in the production of yarn from staple fibers.

DRAGGED-IN FILLING: See PULLED-IN FILLING.

DRAINAGE FABRICS: See GEOTEXTILES.

DRAPE: A term to describe the way a fabric falls while it hangs; the suppleness and ability of a fabric to form graceful configurations.

DRAW-BACK: A crossed end; an end broken during warping that when repaired was not free or was tied in with an adjacent end or ends overlapping the broken end. The end draws or pulls back when unwound on the slasher. (Also see STICKER, 1.)

DRAW-CRIMPING: See DRAW-TEXTURING.

DRAW DOWN: The amount by which manufactured filaments are stretched following extrusion. (Also see DRAWING, 2.)

DRAW-FRAME BLENDS: Blends of fibers made at the draw frame by feeding in ends of appropriate card sliver. This method is used when blend uniformity is not a critical factor.

DRAWING:

1. The process of attenuating or increasing the length per unit weight of laps, slivers, slubbings, or rovings.
2. The hot or cold stretching of continuous filament yarn or tow to align and arrange the crystalline structure of the molecules to achieve improved tensile properties.

DRAWING-IN: In weaving, the process of threading warp ends through the eyes of the heddles and the dents of the reed.

DRAWN TOW: A zero-twist bundle of continuous filaments that has been stretched to achieve molecular orientation. (Tows for staple and spun yarn application are usually crimped.)

DRAW RATIO: The ratio of final to original length per unit weight of yarn, laps, slivers, slubbings, rovings, etc., resulting from drawing. (Also see DRAFT RATIO and DRAW DOWN.)

DRAW-SIZING: A system linking drawwarping and sizing in a continuous process. A typical system includes the following elements: (1) creel, (2) eyelet board, (3) warp-draw machine, (4) intermingler, (5) tension compensator and break monitor, (6) sizing bath, (7) dryers, (8) waxing and winding units.

DRAW-TEXTURING: In the manufacture of thermoplastic fibers, the simultaneous process of drawing to increase molecular orientation and imparting crimp to increase bulk.

DRAW-TWISTING: The operation of stretching continuous filament yarn to align and order the molecular and crystalline structure in which the yarn is taken up by means of a ring-and-traveler device that inserts a small amount of twist (usually ¼ to ½ turn per inch) into the drawn yarn.

DRAW-WARPING: A process in which a number of threadlines, usually 800 to 2000 ends of POY feedstock, are oriented under essentially equal mechanical and thermal conditions by a stretching stage using variable speed rolls, then directly wound onto the beam. This process gives uniform end-to-end properties.

DRAW-WINDING: The operation of stretching continuous filament yarn to align or order molecular and crystalline structure. The drawn yarn is taken up on a parallel tub or cheese, resulting in a zero-twist yarn.

DRILL: A strong denim-like material with a diagonal 2 x 1 weave running toward the left selvage. Drill is often called khaki when it is dyed that color.

DROPPED STITCHES: A defect in knit cloth characterized by recurrent cuts in one or more wales of a length of cloth.

DROP STITCH: 1. An open design made in knitting by removing some of the needles at set intervals. 2. A defect in knit fabric.

DROP WIRES: A stop-motion device utilizing metal wires suspended from warp or creeled yarns. When a yarn breaks, the wire drops, activation the switch that stops the machine.

DRY CLEANING: Removing dirt and stains from fabrics or garments by processing in organic solvents (chlorinated hydrocarbons or mineral spirits).

DRY FILLING: The application of finishing chemicals to dry fabric, usually by padding.

DRY FORMING: The production of fiber webs by methods that do not use water or other liquids, i.e., air-laying or carding.

DRYING CYLINDERS: Any of a number of heated revolving cylinders for drying fabric or yarn. They are arranged either vertically or horizontally in sets, with the number varying according to the material to be dried. They are often internally heated with steam and Tefloncoated to prevent sticking.

DRY-LAID NONWOVENS: Nonwoven web made from dry fiber. Usually refers to fabrics from carded webs versus air-laid nonwovens which are formed from random webs.

DRY SPINNING: See SPINNING.

DUCK: A compact, firm, heavy, plain weave fabric with a weigh of 6 to 50 ounces per square yard. Plied yarn duck has plied yarn in both warp and filling. Flat duck has a warp of two single yarns woven as one and a filling of either single or plied yarn.

DUCK EYE: See SPINNING.

DULL: A term applied to manufactured fibers that have been chemically or physically modified to reduce their normal luster. Matte; opposite of bright; low in luster.

DUMBELLS: A defect frequently seen in wet-formed nonwoven fabrics; an unusually long fiber will become entangled with groups of regular-length fibers at each end, thus producing a dumbbell-shaped clump.

DUNGAREE: A term describing a coarse denim-type fabric, usually dyed blue, that is used for work overalls.

DUPLEX PRINTING: See PRINTING.

DURABILITY: A relative term for the resistance of a material to loss of physical properties or appearance as a result of wear or dynamic operation.

DURABLE PRESS: A term describing a garment that has been treated so that it retains its smooth appearance, shape, and creases or pleats in laundering. In such garments no ironing is required, particularly if the garment is tumble-dried. Durable press finishing is accomplished by several methods; two of the most common are the following: (1) A fabric that contains a thermoplastic fiber and cotton or rayon may be treated with a special resin that, when cured, imparts the permanent shape to the cotton or rayon component of the fabric. The resin-treated fabric may be precured (cured in finishing and subsequently pressed in garment form at a higher temperature to achieve the permanent shape) or postcured (not cured until the finished garment has been sewn and pressed into shape). In both cases, the thermoplastic fiber in the garment is set in the final heat treatment. This fiber, when heat-set, also contributes to the permanence of the garment shape, but the thermoplastic component of the blend is needed for strength since the  cotton or rayon component is somewhat degraded by the durable-press treatment. (2) Garments of a fabric containing a sufficient amount of a thermoplastic fiber, such as polyester, nylon, or acrylic, may be pressed with sufficient pressure and time to achieve a permanent garment shape. (Also see EASE-OF-CARE, PERMANENT FINISH, and WASH-AND-WEAR.).

DUST-RESISTANT: A term applied to a fabric that has been tightly woven so that it resists dust penetration. 

DWELL TIME: The time during a process in which a particular substance remains in one location (e.g., the time during which molten polymer remains in a spinning pack.)

DYE FLECK: 1. An imperfection in fabric caused by residual undissolved dye. 2. A defect caused by small sections of undrawn thermoplastic yarn that dye deeper that the drawn yarn.


DYEING: A process of coloring fibers, yarns, or fabrics with either natural or synthetic dyes. Some of the major dyeing processes are described below:

Batik: A resist-dyeing process in which portions of a fabric are coated with wax; during the dyeing process, only the uncovered areas take up dye. The process can be repeated so that several colors are used. Batik dyeing is often imitated in machine printing.

Chain Dyeing: A method of dyeing yarns and fabrics of low tensile strength of tying them endto- end and running them through the dyebath in a continuous process.

Cross Dyeing: A method of dyeing blend or combination fabrics to two or more shades by the use of dyes with different affinities for the different fibers.

High-Temperature Dyeing: A dyeing operation in which the aqueous dyebaths are maintained at temperatures greater than 100°C by use of pressurized equipment. Used for many manufactured fibers.

Ingrain: Term used to describe yarn or stock that is dyed in two or more shades prior to knitting or weaving to create blended color effects in fabrics.

Jet Dyeing: High temperature piece dyeing in which the dye liquor is circulated via a Venturi jet thus providing the driving force to move the loop of fabric.

Mass-Colored: A term to describe a manufactured fiber (yarn, staple, or tow) that has been colored by the introduction of pigments or insoluble dyes into the polymer melt or spinning solution prior to extrusion. Usually, the colors are fast to most destructive agents.

Muff Dyeing: A form of yarn dyeing in which the cone has been removed.

Package Dyeing: See DYEING, Yarn Dyeing.

Pad Dyeing: A form of dyeing whereby a dye solution is applied by means of a padder or mangle.

Piece Dyeing: The dyeing of fabrics “in the piece,” i.e., in fabric form after weaving or knitting as opposed to dyeing in the form of yarn or stock.

Pressure Dyeing: Dyeing by means of forced circulation of dye through packages of fiber, yarn, or fabric under superatmospheric pressure.

Printing: See PRINTING.

Reserve Dyeing:

1. A method of dyeing in which one component of a blend or combination fabric is left undyed. The objective is accomplished by the use of dyes that have affinity for the fiber to be colored but not for the fiber to be reserved. 
2. A method of treating yarn or fabric so that in the subsequent dyeing operation the treated portion will not be dyed.

Short-Liquor Dyeing: A term used to describe any yarn or piece dyeing in which the liquor ration has been significantly reduced. The technique was designed to save water and energy.

Skein Dyeing: The dyeing of yarn in the form of skeins, or hanks.

Solution Dyeing: See DYEING, Mass-Colored.

Solvent Dyeing: A dyeing method based on solubility of a dye in some liquid other than water, although water may be present in the dyebath.

Space Dyeing: A yarn-dyeing process in which each strand is dyed with more that one color at irregular intervals. Space dyeing produces an effect of unorganized design in subsequent fabric form. The two primary methods are knit-de-knit and warp printing.

Spun-Dyed: See DYEING, Mass-Colored.

Stock Dyeing: The dyeing of fibers in staple form.

Thermal Fixation: A process for dyeing polyester whereby the color is diffused into the fiber by means of dry heat.

Union Dyeing: A method of dyeing a fabric containing two or more fibers or yarns to the same shade so as to achieve the appearance of a solid colored fabric.

Yarn Dyeing: The dyeing of yarn before the fabric is woven or knit. Yarn can be dyed in the form of skeins, muff, packages, cheeses, cakes, chain-wraps, and beams.

DYEING AUXILLARIES: Various substances that can be added to the dyebath to aid dyeing. They may necessary to transfer the dye from the bath to the fiber or they may provide improvements in leveling, penetration, etc. Also call dyeing assistants.

DYE MIGRATION: See MIGRATION, 1.

DYE RANGE: A broad term referring to the collection of dye and chemical baths, drying equipment, etc., in a continuous-dyeing line.

DYES: Substances that add color to textiles. They are incorporated into the fiber by chemical reaction, absorption, or dispersion. Dyes differ in their resistance to sunlight, perspiration, washing, gas, alkalies, and other agents; their affinity for different fibers; their reaction to cleaning agents and methods; and their solubility and method of application. Various classes and types are listed below. [Also see COLOUR INDEX (CI).]

Acid Dyes: A class of dyes used on wool, other animal fibers, and some manufactured fibers. Acid dyes are seldom used on cotton or linen since this process requires a mordant. Acid dyes are widely used on nylon when high washfastness is required. In some cases, even higher washfastness can be obtained by aftertreatment with fixatives.

Aniline Dyes: Dyes derived chemically from aniline or other coal tar derivatives.

Anthraquinone Dyes: Dyes that have anthraquinone as their base and the carbonyl group (>C=O) as the  chromophore. Anthraquinone-based dyes are found in most of the synthetic dye classes.

Azo Dyes: Dyes characterized by the presence of an azo group (-N=N-) as the chromophore. Azo dyes are found in many of the synthetic dye classes.

Azoic Dyes: See DYES, Naphthol Dyes.

Basic Dyes: A class of positive-ion-carrying dyes known for their brilliant hues. Basic dyes are composed of large-molecule, water-soluble salts that have a direct affinity for wool and silk and can be applied to cotton with a mordant. The fastness of basic dyes on these fibers is very poor. Basic dyes are also used on basic-dyeable acrylics, modacrylics, nylons, and polyesters, on which they exhibit reasonably good fastness.

Cationic Dyes: See DYES, Basic Dyes.

Developed Dyes: Dyes that are formed by the use of a developer. The substrate is first dyed in a neutral solution with a dye base, usually colorless. The dye is then diazotized with sodium nitrate and an acid and afterwards treated with a solution of B-naphthol, or a similar substance, which is the developer. Direct dyes are developed to produce a different shade or to improve washfastness or lightfastness.

Direct Dyes: A class of dyestuffs that are applied directly to the substrate in a neutral or alkaline bath. They produce full shades on cotton and linen without mordanting and can also be applied to rayon, silk, and wool. Direct dyes give bright shades but exhibit poor washfastness. Various aftertreatments are used to improve the washfastness of direct dyes, and such dyes are referred to as “aftertreated direct colors.”

Disperse Dyes: A class of slightly water-soluble dyes originally introduced for dyeing acetate and usually applied from fine aqueous suspensions. Disperse dyes are widely used for dyeing most of the manufactured fibers.

Fiber-Reactive Dyes: A type of water-soluble anionic dye having affinity for cellulose fibers. In the presence of alkali, they react with hydroxyl groups in the cellulose and thus are liked with the fiber. Fiber reactive dyes are relatively new dyes and are used extensively on cellulosics when bright shades are desired.

Gel Dyeing: Passing a wet-spun fiber that is in the gel state (not yet at full crystallinity or orientation) through a dyebath containing dye with affinity for the fiber. This process provides good accessibility of the dye sites.

Macromolecular Dyes: A group of inherently colored polymers. They are useful both as polymers and as dyes with high color yield. The chromophores fit the recognized CI classes, i.e., azo, anthraquinone, etc., although not all CI classes are represented. Used for mass dyeing, hair dyes, writing inks, etc.

Metallized Dyes: A class of dyes that have metals in their molecular structure. They are applied from an acid bath.

Naphthol Dyes: A type of azo compound formed on the fiber by first treating the fiber with a phenolic compound. The fiber is then immersed in a second solution containing a diazonuim salt that reacts with the phenilic compound to produce a colored azo compound. Since the phenolic compound is dissolved in caustic solution, these dyes are mainly used for cellulose fiber, although other fibers can be dyed by modifying the process. (Also see DYES, Developed Dyes.)

Premetallized Dyes: Acid dyes that are treated with coordinating metals such as chromium. This type of dye has much better wetfastness than regular acid dye. Premetallized dyes are used on nylon, silk, and wool.

Sulfur Dyes: A class of water-insoluble dyes that are applied in a soluble, reduced form from a sodium sulfide solution and are then reoxidized to the insoluble form on the fiber. Sulfur dyes are mainly used on cotton for economical dark shades of moderate to good fastness to washing and light. They generally give very poor fastness to chlorine.

Vat Dyes: A class of water-insoluble dyes which are applied to the fiber in a reduced, soluble form (leuco compound) and then reoxidized to the original insoluble form. Vat dyes are among the most resistant dyes to both washing and sunlight. They are widely used on cotton, linen rayon, and other cellulosic fibers.

DYE SITES: Functional groups within a fiber that provide sites for chemical bonding with the dye molecule. Dye sites may be either in the polymer chain or in chemical additives included in the fiber.

DYESTUFF: See DYES.

DYNAMIC ADHESION: The ability of a cord-to-rubber bond to resist degradation resulting from flexure.

DYNAPOINT PROCESS: A continuous computer-controlled process for manufacturing tufted carpets with intricate patterns from undyed yarn. The carpet is dyed as it is tufted and the colors and pattern are clearly visible through the primary backing of the carpet.