Glossary for Dyes and Pigments

Acid Dye- A class of dyes that are applied to polyamide fibres from acidic solutions. Essentially synthetic dyes, and used for silk, wool and nylon.

Aniline- Aniline is a very commonly used term in the synthesis of dyes. Represented by the chemical formula of C6H7N. It is also known as aniline oil. Aniline dye is used as a sort of synonym for synthetic dyes.

Affinity- In dyeing process, the affinity means the preferential attraction of dye towards fibre rather than for solution of the dye bath. A dye that has strong affinity easily leaves the dye solution of dispersion. And attaches itself to the fibre being dyed.

Azo- Azo refers to a chemical compound that contains double nitrogen atoms with a double bond between them (-N=N-). Azo dyes forms the largest group of dyes. They display light-fastness, stability, strongness and respond well to mixing. They may be found among the dye classes of direct, acid, basic, reactive and disperse.

Basic Dye- The dyes that are able to react with acidic groups on fibres.

Bifunctional Reactive Dye- These dyes can react with the fibre in more than a single way.

Binder- A colorless material used to attach a pigment to fabric. They are like "glue" that holds the pigment in place. Example: Paints that has pigments mixed with binders.

Cation- The positively charged ions, widely applied in textile processing.

Cellulose- A polymer consisting of a large numbers of units, each of the general formula represented by C6H10O5.

Chromophore- A color-bearing compound that has a special property found in an organic molecule which make it appear colored.

Color Index- A publication jointly brought out by the Society of Dyers and Colorists of Great Britain and the American Association of Textile Chemists and Colorists.

Chrome- Any salt of chromium, that is used in tanning and dyeing.

Direct Dye- A dye that is carried out by immersing the fibre in a dye solution without any requirement of other chemicals for bonding the dye to the fibres.

Direct application- A method usually used to describe a process where a solution of dye is locally applied to different areas of fabric, like squirting, painting, spraying, stamping, etc.

Disperse Dye- These dyes are found in the dye bath as a kind of suspension or dispersion of microscopic particles, with only a minuscule amount in true solution at any given moment of time.

Exhaust Dyeing- Exhaust Dyeing allows the dye molecules to exit the bath and get attach to the fibres.

Enzyme- The type of protein that perform the role of a catalyst in a biochemical reaction. Examples: Amylase - applied for desizing; Cellulase - Used in modification of cellulosic fabrics.

Fixation- It refers to the formation of a sort of final bond between the fibre and dye. The bond type formed changes with the type of dye and the fibre.

FBA- Fluorescent brightening agent.

Gel Dyeing- A continuous type of tow-dyeing method where soluble dyes are used to wet-spun fibres in the gel state (i.e. After the processes of extrusion and coagulation, but before drying and drawing).

Hardness- A measurement that ascertains the content of minerals that imparts specific properties.

Illuminating Dye- This dye get mixed with discharge paste in printing methods and also referred to as head dyes.

Indigo- A sort of natural or synthetic vat dye given the designation of Color Index Vat Blue 1. Indigo is perhaps one of the oldest colorants that is used for textiles. Originally extraction was done from plants, but now it is usually synthetic.

Jet Dyeing- Used in dyeing of Polyester.

Kilogram- Unit of mass (weight) in the system of metric. It equals approximately 2.2 pounds avoirdupois.

Lightfastness- This term is typically used as measurement to ascertain how resistant a coloring material, such as dye would be fading when exposed to light.

Liquor ratio (also liquor to goods ratio)- It is the ratio that is used to denote the weight of the dyebath or any other processing bath to the weight of goods that is being dyed or processed.

Metal-Complex Dye- A dye that typically has co-ordinated metal atoms in its molecule.

Mordant- Chemicals that helps in attachment of dyestuff to fibres by bonding to the fibre as well as to the dye.

Non-ionic - A chemical that does not ionize in a solution while remaining is in intact molecular form some surfactants are non-ionic.

No-wick HF- Used with Liquid Decorator Colors, for enabling fine line drawing.

pH- The measurement of the concentration of hydronium that is found in a solution.

Pigment- A substance used in the particulate form that is substantially insoluble in a medium.

Reactive Dye- These dyes can react chemically with a substrate for forming a covalent dye-substrate linkage.

Retayne- A type of cationic dye fixing agent. Typically used on cotton fabrics for improving wet fastness of the direct dyes and to add color paper pulp.

Sublimation- It is the conversion of solid directly into gas, without passing through the liquid phase.

Sodium Hydroxide- It is a strong base; also called caustic soda or lye, or just "caustic" in dyeing terms. Chemical Formula: NaOH.

Sulphur Dye- A dye, that contains sulphur as an integral part of the chromophore and as well as in attached polysulphide chains. Sulphur dyes are not soluble in water, and must get converted to a soluble form before application.

Tannic Acid- A mixture of compounds derived from natural sources like oak.

Ultraviolet- The light that is beyond the portion that is visible of the light spectrum at the blue end. It is the Ultraviolet light that causes fading of colors, and makes fluorescent compounds glow.

Union Dye- A dye that is generally a mixture of two or more different classes of dye. It is used to dye blends of fibres.

Vat Dye- Vat dyes are water-insoluble dye containing keto groups, which is normally applied to the fibre from an aqueous alkaline solution of the reduced enol (leuco) form, that subsequently gets oxidised in the fibre to an insoluble form.

Vinyl Sulphone- Vinyl sulphone reactive dyes are generally intermediate in their reactivity, so they are used above room temperature, but considerably below the boiling point of water. These are typically used for cellulosic fibres and with some use for wool also.

Washfastness- Washfastness is used to measure resistance of a dye to washing out.

Wetting Agent- These are generally used in the dyeing process where it helps the dye solution to penetrate to the individual fibres.

Yarn Dyeing- Yarn gets dyed before being woven into fabric.

Zinc Formaldehyde Sulphoxylate- A Color Index Reducing Agent 6, used for application in discharge.