Dyeing Glossary | Essential Terms and Definition of Dyeing (Part-1)

Dyeing Glossary | Essential Terms and Definition of Dyeing
Rana Sohel
Production Officer (Dyeing)
Sunman Textile Mills Ltd. Chittagong
Cell: +8801912-420118
Email: rsohel07tex@gmail.com


Dyeing Glossary
Dyeing glossary contains terms specific to dyeing. It is not intended to provide enough information by itself to serve as a guide for dyeing. Terms have been included here because they may appear in dyeing literature, and may be hard to find in ordinary dictionaries. This dyeing terms will help the students in viva board both educational and job life.
Essential Terms and Definition of Dyeing:

Absorbency: The ability of one material to take up another material.

Absorption: The process of gases or liquids being taken up into the pores of a fiber, yarn, or fabric.

Acetic acid: An organic acid (CH3COOH) widely used in textile applications. It is used in textile wet processing, dyeing and printing, and in the manufacture of cellulose acetate and cellulose triacetate.

Acetic, anhydride: Anhydrous acetic acid [(CH3CO)2O]. It is used in the acetylation process in the manufacture of cellulose acetate.

Acetone: Diemthyl ketone (CH3COOH). One of the most powerful organic solvents. Acetone dissolves secondary cellulose acetate and other derivatives of cellulose. It is miscible with water and has a low boiling point(55-56oC)

Acid: Having a low pH.

Acid dyes: An anionic dye having substantivity for fibers (e.g. Protein, polyamide) which contain cationic groups usually in acidic or neutral aqueous dyebaths. Acid dyes are often applied to fabric in organic or inorganic acid dyeing solution.

Acid-dyeable variants: Polymers modified chemically to make them receptive to acid dyes.

Acidic: A term describing a material having a pH of less than 7.0 in water.

Activated oxygen bleach: A bleaching system comprising an oxygen bleach and a bleach activator.

Add-on: The amount of materials applied to a textile is known add-on; it is calculated as the weight of solids left on a given weight of fabric after impregnation and drying. The percentage add-on is computed by the formula {(w2-w1) ×100}/ w1; where w1 is the initial weight of material before impregnation (wet-out), and w2 is the weight of material after impregnation and drying.

Additive: A supplementary material combined with a base material to provide special properties.

Adjective Dye: A dye that requires a mordant to be fast. Most natural dyes are adjective.

Adsorption: The attraction of gases, liquids or solids to surface areas of textile fibers, yarns, fabrics or any materials.

Aerobic: A biological process active only in the presence of oxygen.

Affinity: Chemical attraction; the tendency of two elements or substances to unite or Combine together, such as fiber and dyestuff. Affinity is usually expressed in units of joules (or calories) per mole.

Aftertreatment: Any treatment done after fabric production. In dyeing, it refers to treating dyed material in ways to improve properties; in nonwovens, it refers to finishing processes carried out after a web has been formed and bonded. Examples are embossing, creping, softening, printing and dyeing.

Ageing: Ageing consists of exposing printing goods to more or less prolonged action of steam at atmospheric pressure to assist in the diffusion & fixation of the dyes

Alkaline: A term used to describe a material having a pH greater than 7.0 in water.

Anaerobic: A biological process active only in the absence of free oxygen.

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

Anionic dye: A dye dissociates in aqueous dyebath and provide negatively charged colored ion.

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.

Antichlor: A chemical, such as sodium thiosulfate , used to remove excess chlorine after bleaching.

Auxiliaries: Chemicals used to facilitate and modify the dyeing process. Most dyes require auxiliaries, though some (likeCountry Classics) come pre-measured with powdered auxiliaries.

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: The dyes, produced by interaction of a diazotized amine (azoic diazo component) and a coupling component (azoic coupling component).

Bacterial Amylase Unit (BAU): A measure of starch degradation as shown by the quantity of an enzyme that will dextrinize one milligram of starch per minute under the specified experimental conditions.

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.

Batch: A group of units of products of the same type, structure, colour and finish, class and composition, manufactured under essentially the same conditions and essentially at the same time, and submitted at any one time for inspection and testing. Similar word ‘Lot’.

Bath ratio: Ratio of bath to fiber as 20:1, 10:1 or 1:20, 1:10

Binder: The binder is a film forming substance made up of long chain macromolecules which when applied to textile together with the pigment; produce a three dimensionally linked network.

Bleaching: A process of whitening fibers, yarns, or fabrics by removing the natural and artificial impurities to obtain clear whites for finished fabric, or in preparation for dyeing and finishing. The materials may be treated with chemicals or exposed to sun, air, and moisture.

Bleeding: Color rinsing out of a finished garment, yarn, or fiber. Bleeding can be excess dye that was not fully rinsed out or dye that was not properly set on the fiber. Indigo is an exception, see crocking.

Buffering Agent (Buffer): A chemical additive that helps stabilize the dyebath pH. Also improves leveling.

Carbonizing: A chemical process for eliminating cellulosic material from, synthetic and wool or other animal fibers. The material is reacted with sulfuric acid or hydrogen chloride gas followed by heating. When the material is dry, the carbonized cellulose material is dust-like and can be removed.

Carrier: A product added to a dye-bath to promote the dyeing of hydrophobic manufactured fibers and characterized by affinity for, and ability to swell, the fiber.

Cat-ion: A positively charged ion.

Cationic dyes: A dye that dissociates in an acidified, aqueous solution to give a positively charged colored ion.

Caustic Soda: The common name for sodium hydroxide (NaOH)

Chrome dye: A mordant dye capable of forming a chelate complex with a chromium ion.

CIE: Commission internationaly de I’Eclairage.

CMC: Carboxymethyl cellulose. Synthetic size used in cotton fabric processing.

Colorant: A colouring matter, a dye or pigment which can produce colour in a substrate like fiber, yarn or fabric.

Coloration: A series of textile operation involved to impart color in textiles. It embraces dyeing, printing, painting, spraying and preparatory treatment as well.

Color: (Sensation) that characteristic of the visual sensation which enables the eye to distinguish differences in its quality, such as may be caused by differences in spatial distribution or fluctuation with time. (of an object) the particular visual sensation caused by the light emitted by, transmitted through, or reflected from the object.

Colour can be described approximately in terms of Hue, Saturation, and Lightness, or specified numerically by chromaticity coordinates. Alternatively , colour can be specified by reference to visual standards e.g. the Munsell Color Atlas.

Colorfastness: Resistance to fading; i.e the property of a dye to retain its color when the dyed (or printed) textile material is exposed to conditions or agents such as light, perspiration, atmospheric gases, or washing that can remove or destroy the color.

Color strength: A measure of the ability of a dye to impart color to other materials. Color strength is evaluated by light absorption in the visible region of the spectrum.

Colorist: In textile coloration, a person experienced in developing color formulas, evaluating samples for color and producing colored samples to meet standards.

Color index (CI): A listing of dyes and chemical structures published by the Society of Dyers and Colorists. Each structure is assigned a name according to chemical composition. Each dye is assigned a number according to its class and shade. A correlating structure number is given when available.

Color Temperature: Hues on the color wheel located closer to orange are warm colors; those closer to blue are cool colors.

Compatibility: In textile dyeing, propensity of individual dye components in a combination shade to exhaust at similar rates resulting in a buildup of shade that is constant, or nearly constant, in hue throughout the dyeing process.

Copper chelating value (CuCV): The milligrams of copper sulfate pentahydrate chelated by one gram of a chelating agent or product containing a chelating agent.

Crocking: Crocking refers to blue indigo dye that comes off during spinning or knitting. Indigo in this state cannot stain anything washable like skin or clothing. It may stain wood or bamboo needles, as they are porous and not usually washable. Crocking will cease after a few washings.

Cross dyeing: A process of dyeing textiles containing fibers having different dye affinities to achieve a multicolored effect.

Depth of Shade (DOS): a percentage describing the amount of dye used proportional to the dry fiber weight, or OWOG. To dye 100 grams of fiber to a 1% DOS, your dye powder would weigh 1% of 100 grams, or 1 gram.

Desizing: The process removal of size materials from greige (gray) fabric to prepare for dyeing.

Detergent: A detergent is a compound or a mixture of compounds, intended to assist cleaning & acts mainly on the oily films that trap dirt particles.

Dip: Immersion of a textile material in some processing liquid. The term is usually used in connection with a padding or slashing process.

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.

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

Dyes/dyestuff: Substances that add color to textiles. They are incorporated into the fiber by chemical reaction, absorption, or dispersion. Dyes may be divided into natural and synthetic types. Natural dyes are extracted from root bark, flowers and marine growth. Synthetic dyes are chemically compounded through many processes from coal tar or other sources of hydrocarbon molecules. On basis of application it is classified as Acid dye, Azoic dye, Basic dye, Direct dye, Disperse dye, Mordant dye, Reactive dye, Sulphur dye, Vat dye etc. Fluorescent whitening agent is also a dye.

Dyeing: A process of coloring fibers, yarns, fabrics or garments with either natural or synthetic dyes under specified conditions.

Dyeing auxiliaries: 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 liquor: The liquid that contains the dye and the reagents necessary for dyeing.

Ecmc: In color difference evaluation, a single number defining the total color difference in CMC units of a trial from a standard.

Emulsion: A suspension of finely divided liquid droplets in a second liquid, i,e., oil in water or vice versa.

Exhaustion: During wet processing, the ratio at any time between the amount of dye or substance taken up by the substrate and the amount originally available.

Fast or Fastness: A fast color will not fade due to exposure to light or washing.

Fixation: The process of setting a dye after dyeing of printing, usually by steaming or other heart treatment.

Fluorescent: A substance that is added to a textile (uncolored or colored) to increase the apparent light reflectance in the visible region by the conversion of ultraviolet radiation into visible light and so to increase the apparent brightness or whiteness of the textile. Similar words brightener.

Florescent whitening agent (FWA): Colorant that absorbs near ultraviolet (UV) radiation and re-emits visible (violet-blue) radiation. This causes a yellowish material to which it has been applied to appear whiter.

Foam: Dispersion of gas in a liquid or solid. The gas bubbles may be any size. The term covers a wide range of useful products such as insulating foam, cushions, etc. It also describes the undesirable froth in polymer melts, dye baths, etc.

Foam Finishing: The application of one or more liquid chemicals finishes in the form of a foam to a textile material with the advantage of low wet pick-up

Hard water: Water described as "hard" is high in dissolved minerals, specifically aclcium and magnesium. Hard water is not a health risk, but a nuisance because of mineral buildup on fixtures and poor soap and/or detergent performance.

Heat setting: Heat-setting is a heat treatment by which shape retention, crease resistance, resilience and elasticity are imparted to the fibres. It also brings changes in strength, stretchability, softness, dyeability and sometimes on the color of the material. All these changes are connected with the structural and chemical modifications occurring in the fibre.

Hue: The attribute of color perception by means of which an object is judged to be red, orange, yellow, green, blue, violet or a combination of these.

Hydrolysis: A double decomposition reaction involving the addition of the elements of water and the formation of an acid and a base, an acid and an alcohol, or an acid and phenol.

Hydrophilic: Having strong affinity for or the ability to absorb water.

Hydrophobic: Lacking affinity for or the ability to absorb water.

Part-2


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