Glossary

Acid dye	an anionic dye (see Anionic dye) which forms ionic links with cationic substances in the fibre.
Affinity	within the context of this handbook affinity is an attraction between the dye and the substrate.
Anionic dye	a dye that gives negatively-charged coloured ions
Balance	sensitive scales used in laboratories for weighing materials accurately.
Basic dye	a cationic dye (see Cationic dye) which forms links with anionic substances in the fibre.
Batchwise processing	a process in which the whole of the material passes through each treatment as a single unit (batch). It thus differs from continuous processing in which all the material passes successively through each treatment stage as for example when a roll of cloth passes through a bath from beginning to end.
Baumé (° Be)	an arbitrary scale of specific gravities (see Specific gravity) devised by French chemist Antoine Baumé.There are two scales having, at 60° F, the following relationships to specific gravity:
	(i) Materials more dense than water
	°Bé= (145 - 145)/Specific gravity
	(ii) Materials less dense than water
	°Bé = (1 40 - 1 30)/Specific gravity
	(Appendix 1, Table C uses the scale for materials more dense than water).
Blending	mixing two or more different dyes in order to match a particular hue (see Hue).
Cationic after-treating	a colourless basic dye which is applied to fibre dyed agent with direct or reactive dyes to make the dye more water fast by forming larger molecules which migrate out of the material less readily.
Cationic dye	a dye that gives positively-charged colouredions
Cellulosic	made of or containing cellulose - a chemical, based on the sugar glucose, found in all plants. Some fibres, e.g. cotton, consist almost entirely of cellulose; others, such as jute and sisal, consist of about 70 per cent cellulose.
Colour Index	an authoritative, descriptive catalogue of natural and synthetic colourants and intermediates in terms of generic name and constitution where disclosed.
Complex	a large molecule formed by an association between two or more smaller molecules. Complexes may be formed between dyes and metals (as in 1:2 metal complex dyes) or between cationic after-treating agents (see Cationic after-treating agent) and dyes containing anionic water solubilising groups (see Anionic dye).
Contrast	the degree of visible difference between two adjacent materials. For example black and white produce a high contrast whilst grey and white or grey and black produce a lower contrast.
Depth	the colour quality that is associated with the amount of dyestuff present. Increased dyestuff gives increased depth. In dyeing, depth is usually the amount of dyestuff used in the dyebath expressed as a percentage of the weight of air-dry fibre dyed (see also Standard depth).
Direct dye	an anionic dye having substantivity (see Substantivity) for cellulosic fibres
Disperse dye	a dye which will disperse but not dissolve in water and be adsorbed by certain synthetic fibres (e.g. polyester, acetate, nylon).
Dispersol dye	an Imperial Chemical Industries plc (ICI) brand of disperse dye.
Dylon Cold	reactive dyes packaged in sizes convenient for the home dyer marketed by Dylon International Ltd.
Dylon Multi-purpose	International Ltd, which will colour almost any textile material.a blend (see Blending) of dyes marketed by Dylon dye
Exhaust dyeing	-a batchwise dyeing process (see Batchwise processing) in which the dye is attracted to, and gradually adsorbed onto, the material from a large volume of liquor, until the dye in the liquor is exhausted. The dyebath is discarded on completion as opposed to the use of a standing bath (see Standing bath. See also Pad-batch dyeing).
Fastness	the ability of a colour to resist change when exposed to light or water, etc.
Generic Name	the ColourIndex classification of a colourant or intermediate according to application properties. Dyestuffs which share the same Colour Index Generic Name usually contain the same chemical as their major component.
Hue	the visual colour, e.g. red, blue, green, etc. (See also Shade).
Insoluble	chemicals which remain solid when stirred in a liquid (see Disperse dyes).
Ionic	chemicals which in solution yield anionic and cationic particles (ions) (see Anionic dye and Cationic dye).
Liquor	the liquid containing the dissolved chemicals used for processing textiles.
Liquor ratio	the ratio of the weight of liquor used in processing to the weight of air-dry material processed, e.g. Iiquor ratio 20:1 means, for example, 20 kg of liquor used on 1 kg air-dry material. Low liquor ratio is called a 'short' liquor; high liquor ratio is called a 'long' liquor.
Metal complex dye	a dye comprising simple dye molecules complexed with a metal to form larger, more water fast molecules -a 2:1 metal complex has two dye molecules associated with one metal atom.
Molecule	the smallest particle of a compound which can exist as that particular chemical substance. It is composed of atoms-the smallest particle of a chemical element that can exist as a discrete substance. Some molecules (e.g. sodium chloride! are made up of only two atoms (one of sodium and one of chlorine) whilst others (dye molecules for example) are composed of around 1 00 atoms.
Normal depth see
Pad-batch dyeing	Standard depth. methods of dyeing in which the dye is first 'padded' on the material (see Padding) and the material is then left for a period of time to allow the dye to penetrate into and fix onto the fibres ('batching') (see Canning et al. (1977)).
Padding	distributing liquor throughout the material, often by dipping and then squeezing to remove the excess.
Procion MX dye	-a dyestuff made by Imperial Chemical Industries plc (ICI), which reacts chemically in the cold with cellulose. The reacted dye cannot be removed from the cellulose by ordinary physical means, e.g. washing .
Reactive dye	a dye which is designed to react chemically with the substrate (see Substrate).
Sequestering agent	a compound which prevents metallic ions from causing unwanted reactions by forming a complex with them.
Shade	term used in dyeing to describe the depth of colour, e.g. 'light', ‘dark','pale', 'deep', etc. (see also Depth and Standard depth).
Sisal	a coarse, hard, stiff sisalana .fibre obtained from the leaf of Agave
Sodium bicarbonate	a mild alkali used with TDRl's pad-batch dyeing method to fix the dye. This chemical is also commonly called bicarbonate of soda.
Sodium carbonate	a non-caustic alkali which is stronger than sodium bicarbonate. The anhydrous powder is known as soda ash and the hydrated crystals are 'washing soda'.
Space-dyeing	the production of multi-colour yarns by the application of various dyes at intervals along a yarn.
Specific gravity (Sp.gr.) -	the ratio of the weight of a substance to the weight of the same volume of water.
Standard depth	an arbitrarily chosen medium visual depth, judged to be equal for all hues, which enables dyeing, fastness or other properties to be compared on a uniform basis. Conventionally, standard, or normal, depth is symbolised '1/1 N'; lighter depths as, e.g. '1/3N'; and heavier depths as, e.g. '2/1 N'.
Substantivity	an attraction between a fibre and a dyestuff.
Substrate	the material to which dye is applied.
Synacril dye	an Imperial Chemical Industries plc (ICI) brand of basic dye.
Tinctorial yield	a measure of the strength of a dye. Some dyes (of high tinctorial yield) produce a deep shade with a small amount of dye, whilst others (of low tinctorial yield) give only a pastel shade with the same amount of dye.
Twaddell (°Tw)	a system used for reporting the densities of liquids which are heavier than water. The relationship with specific gravity (see Specific gravity) is: Specific gravity = ((°Tw X 5) + 1,000)/1,000
Vegetable dyes	colouring matters, usually of unknown character and composition, obtained from plants.