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Colour Experience - Dye glossary
Category: Agriculture and Industry > Dye
Date & country: 11/12/2007, UK
Words: 24


Acid dye
An anionic dye characterised by substantivity for protein fibres and often applied from an acid dyebath.

Affinity
The quantitative expression of substantivity. It is the difference between the chemical potential of the dye in its standard state in the fibre and the corresponding chemical potential in the dyebath. Note: Affinity is usually expressed in units of joules (or calories) per mole. Use of this term in a qualitative sense, synonymous with substantivity, is deprecated.

Afterchrome process
A method of dyeing in which the fibre is dyed with a mordant dye and afterwards treated with a chromium compound to form a dye - chromium complex within the fibre.

Anionic dye
A dye that dissociates in aqueous solution to give a negatively charged coloured ion.

Assistant
Substance added to a dyebath of print paste to aid the coloration process.

Auxiliary
A chemical of formulated chemical product which enables a processing operation in preparation, dyeing, printing of finishing to be carried out more effectively or which is essential if a given effect is to be obtained.

Azoic dyeing
The production of an insoluble azo compound on a substrate by interaction of a diazotised amine (azoic diazo component) and a coupling component (azoic coupling component).

Basic dye
A cationic dye characterised by its substantivity for the acidic types of acrylic fibre and for tannin mordanted cotton.

Batchwise processing
Processing of materials as lots or batches in which the whole of each batch is subjected to one stage of the process at a time.

Brightness
The converse of dullness.

Cationic dye
A dye that dissociates in aqueous solution to give a positively charged coloured ion.

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

Compatible dyes
Dyes which when used together behave in dyeing virtually as a homogeneous dye.

Direct dye
An anionic dye having substantivity for cellulosic fibres, normally applied from an aqueous dyebath containing an electrolyte.

Disperse dye
A substantially water-insoluble dye having substantivity for one or more hydrophobic fibres, e.g. cellulose acetate, and usually applied from fine aqueous dispersion.

Dullness
(Of a colour) That colour quality, an increase in which is comparable to the effect of the addition of a small quantity of neutral grey colorant, whereby a match cannot be made by adjusting the strength. Note: It is generally found that an increase in dullness is accompanied by a decrease in both saturation and lightness.

Dye
A substance, usually organic, which is designed to be absorbed or adsorbed by, made to react with, or deposited within a substrate in order to impart colour to the substrate with some degree of permanence.

Gel Dyeing
A continuous tow-dyeing method in which soluble dyes are applied to wet-spun fibres (e.g. acrylic or modacrylic fibres) in the gel state (i.e. after extrusion and coagulation, but before drawing and drying).

Levelling agent
Strictly, a substance that, added to the dyebath, promotes levelling. Note: This term is also widely used to describe substances that do not necessarily promote levelling but which do assist level dyeing.

Metal-complex dye
A dye having a co-ordinated metal atom in its molecule. Note: unless the term 'metal- complex dye' is used in direct association with a particular application class of dye, e.g. 'metal-complex disperse dye' or 'metal-complex reactive dye', its use is deprecated.

Pigment
A substance in particulate form which is substantially insoluble in a medium, but which can be mechanically dispersed in this medium to modify its colour and/or light-scattering properties.

Reactive dye
A dye that, under suitable conditions, is capable of reacting chemically with a substrate to form a covalent dye-substrate linkage.

Sulphur dye
A dye, containing sulphur both as an integral part of the chromophore and in attached polysulphide chains, normally applied in the alkali-soluble reduced (leuco) form a sodium sulphide solution and subsequently oxidised to the insoluble form in the fibre.

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