Cochineal is a dye-stuff consisting of the dried bodies of the females of a species of insect, the Coccus Cacti a native of the warmer parts of America, particularly Mexico, and found living on a species of cactus called the cochineal-fig. The insects are brushed softly off, and killed by being placed in ovens or dried in the sun, having then the appearance of small berries or seeds. A pound of cochineal contains about 70,000 of them. The finest cochineal is prepared in Mexico, where it was first discovered, and Guatemala; but Peru, Brazil, Algiers, the East and West Indies, and the Canary Islands have also produced cochineal more or less success. Cochineal produces crimson and scarlet colours, and is used in making carmine and lake. Research Cochineal
Dyeing is the art of giving colour to textile and other articles in such a way that the colours are more or less permanent, and not readily affected by the action of light, washing, etc. Like spinning and weaving it was originally a home industry, as it still is in many places. Until about 1850 natural dye-stuffs alone were employed, but the discovery of dyes of all colours that can be obtained from coal-tar products revolutionized dyeing as an industry, and the vegetable dye-stuffs were gradually superseded by the newer colours.
Before dyeing, the materials have generally to be cleansed or bleached to get rid of undesirable colouring matters or impurities; and frequently a textile material is subjected to some subsidiary treatment in order to obtain special effects. For example, cottonyarn may be subjected to the action of strong causticsoda ('mercerizing' process) while in a state of great tension, in order to give it a permanent silky lustre.
Dyeing is not only an art, it is also a branch of applied chemistry. One fundamental principle is, that the colouring matter and other necessary substances must be applied in a state of solution, and while in direct contact with the fibre they must be rendered insoluble, so that they are precipitated within or upon the fibre and thus permanently fixed. The method of effecting this varies greatly according to the fibre and the colouring matter employed. As a rule the vegetable and the animal fibres are dyed by very different methods. The affinity of the animal fibres for certain colouring matters is often so great that they are readily dyed by simple immersion in hot colour solutions;
but this simple process is not generally sufficient. According to the method of their application in dyeing the following groups: of dye-stuffs may be distinguished: Avid Colours, Basic Colours, Direct Colours, Developed Colours, Mordant Colours, Miscellaneous Colours, Reactive Colours.
The acid colours are so called because they are of an acid character and are applied in an acid dye-bath. As a rule, they are only suitable for dyeing the animal fibres, e.g. wool and silk, also leather, horn, feathers, etc. Only a few vegetable dye-stuffs belong to this class, for example, the purple colour orchil and the blue colour indigo extract. On the other hand, the acid colours derived from coal-tar - and increasingly petroleum - are very numerous and yield a great variety of hues - red, orange, yellow, green, blue, violet, brown, and black, each with its particular name.
The basic colours are so called because their essential constituents, to which they owe their dyeing power, are organicbases. The bases themselves are colourless and too insoluble in water to be of use, hence they are employed in the form of their soluble coloured salts, usually the hydrochlorides of the colour-bases. Their solutions are precipitated by tannic acid, because it combines with the colour-bases to form insoluble tannates. Wool, silk, and animal substances generally have a direct attraction for colour-bases, and hence these fibres are readily dyed by simple immersion in hot aqueous solutions of the basic colours. Cotton and linen, on the other hand, are not dyed so readily; they need first to be prepared or impregnated with tannic acid, and thus prepared are said to be mordanted, the tannic acid in this connection being styled the mordant. Most of the colours of this class are fugitive to light, and all but one, barberryroot, are derived from coal-tar products.
The direct colours are so called because they dyecotton direct, that is, without the aid of any mordanting process. The first of this class derived from coal-tar was congo red, discovered in 1884; this group includes a very great variety of fast colours, and forms, indeed, one of the most important and valuable series of dye-stuffs employed. Cotton, linen, and the vegetable fibres generally are dyed in the simplest possible manner by merely boiling them in a solution of the dye-stuff, with or without the addition of a little soap, carbonate or sulphate of soda, etc. Wool and silk are frequently dyed in the same manner as cotton. Very few vegetable dye-stuffs belong to the direct colours, e.g. Safflower, Turmeric, Saffron, Annatto. They are all fugitive, and have been of little or no importance to the dyer since the end of the 19th century. The coal-tar colours of this class, on the other hand, are extremely numerous.
The developed colours include a variety of colours which are formed in situ upon the fibre by the successive application of two or more substances. These colours are all of coal-tar origin. A number of them belong to the so-called azo colours, derived from compounds containing nitrogen.
The mordant colours form one of the most important classes of colouring matters, for they include not only most of the vegetable dye-stuffs, e.g. madder, logwood, fustic, etc, but also many valuable fast coal-tar colours, commonly known as the alizarin colours, after their typical representative, alizarin. These mordant colours have by themselves very little colouring power, as a rule, and if employed alone in dyeing give little or no result. If applied, however, in conjunction with metallic salts, notably those of chromium, aluminium, iron, tin, and copper, they each yield a variety of colours, according to the metallic salt employed. In employing them usually two distinct operations are involved: first, that of applying the metallic salt or mordant, called the mordanting process ; and second, that of dyeing proper, in which the mordanted material is boiled in a solution or decoction of the dye-stuff. During the dyeing operation the colouring principle of the dye-stuff combines with the metallic salt already upon the material, and the colour is thus produced and fixed upon the fibre. The method of mordanting varies with the fibre and the metallic salt employed. The vegetable dye-stuffs of this class include Madder, Sapanwood, Camwood, Barwood, Old Fustic, Young Fustic, Quercitron Bark, Persian Berries, Weld, Logwood. Madder was formerly the most important and highly valued of the dye-stuffs of this class, being especially employed to produce the fine 'Turkey-red' dye; but was entirely superseded by the coal-tar colour alizarin towards the end of the 19th century.
Reactive colours combine directly with the fibre being dyed through a chemical reaction and result in a fast colour. The first ranges of reactive dyes for cellulose fibres were introduced in the mid-1950s.
Similarly, the employment of cochineal (an insect dye) has also greatly diminished through the introduction of the cheaper colours. Camwood and barwood are almost entirely used in wool-dyeing, either in conjunction with the indigo-vat or for the purpose of dyeing various shades of brown. Old fustic is the most important of the yellow mordant dye-stuffs, and the colours are fast although not very brilliant. Young fustic yields fugitive colours, and has been little used since 1900. Quercitron bark is an excellent dye-stuff employed by wool-dyers for the production of bright orange and yellow colours. Persian berries and weld, a species of wild mignonette, are both excellent dye-stuffs, but their employment is now limited. Logwood is largely employed by wool, silk, and cotton dyers for dyeing black and dark-blues, which, although fast to washing, are only moderately so towards light. During the 20th century dyewoods were gradually replaced by coal-tar colours.
Among miscellaneous colours are several dye-stuffs applied in a distinct manner. Indigo is a dark-blue powder quite insoluble in water, but can be rendered soluble for dyeing purposes by two methods. The first method converts the indigo into so-called indigo extract, which is sold as a blue paste and applied as an acid colour in dyeing wool and silk. In the second method the indigo-blue is converted into indigo-white, which readily dissolves in the alkalipresent, the solution thus obtained being called an indigo-vat. If cotton, wool, or silk is steeped for some time in the clear yellow solution of such a vat, and then exposed to the oxidizing influence of the air, they are dyed a permanent blue. The indigo-white absorbed by the fibre loses its acquired hydrogen, and thus insoluble indigo-blue is regenerated within and upon the fibre. Aniline black is a valuable colour, produced direct upon the fibre by the oxidation of aniline, and remarkable for its extreme permanency.
Catechu is a vegetable dye-stuff used in dyeing cotton and woollen brown. On wool, catechu yields khaki browns in single bath by using copper sulphate as the mordant. On silk it is largely employed for weighting purposes in the process of dyeing black. Chrome Yellow, Iron Buff, Prussian Blue, and Manganese Brown, employed in cotton dyeing, are frequently classed as mineral colours. Chrome yellow is obtained by immersing cotton successively in solutions of acetate of lead and bichromate of potash, whereby the yellow precipitate of chromate of lead is fixed upon the fibre. Iron buff is obtained in a similar manner by the successive application of iron sulphate and carbonate of soda, and finally developing the full colour by washing with water and exposure to air. The buff colour is really due to the precipitation of oxide of iron on the cotton. Prussian blue is at once developed by passing the buff-dyed cotton through an acidified solution of potassium ferrocyanide. The production of manganese brown on cotton is similar to that of iron buff. The brown colour ultimately produced upon the fibre is an oxide of manganese. The mineral colours are very useful for certain purposes, and are to be regarded as very fast to light. Research Dyeing
The seron was a British measurement of almonds equivalent to between 1.25 and 2 hundred weight, in use during the 19th century.
The seron was a British measure of cochinealequivalent to 140 lbs, in use during the 19th century. Research Seron
Coccus is a genus of insects of the order Hemiptera, family Coccidae, or scale-insects. The males are elongated in their form, have large wings, and are destitute of any obvious means of suction; the females, on the contrary, are of a rounded or oval form, about an eighth of an inch in length, have no wings, but possess a beak or sucker, by which they suck up the juices of the plants on which they live. At a certain period of their life the females attach themselves to the plant or tree which they inhabit, and remain thereon immovable during the rest of their existence. In this situation they are impregnated by the male; after which their body increases considerably, in many species losing its original form and assuming that of a gall, and, after depositing the eggs, drying up and forming a habitation for the young. Some of these insects are troublesome in gardens, plantations, and hot-houses, while others are of great value. for example, kermes, cochineal, lac-lake, lac-dye, and gum-lac are either the perfect insects dried, or the secretions which they form.
Kermes consist of the dried females of Coccus ilicis, found in great abundance upon a species of oak (Quercus coccifera), a native of the Mediterranean basin, and gathered before the eggs are hatched. It was known as a dye-stuff in the earliest times, but has partly fallen into disuse since the introduction of cochineal. Cochineal consists of the bodies of the females of the Coccus cacti, a native of Mexico, which feeds on various species of cactus, particularly on one called nopal (Opuntia cochinillifera). Research Coccus
Cochineal is a scaled insect (Dactylopius coccus or Coccus cacti) found on cacti in Mexico. The dried body of the female is used to prepare the red dye, cochineal. Research Cochineal
Hemiptera is an order of four-winged insects, having a suctorial proboscis, the outer wings, or wing-covers, are either entirely formed of a substance intermediate between the elytra of beetles and the ordinary membranous wings of most insects, or leathery at the base and transparent towards the tips (hemelytra). In one group (the Aphides) all the wings when present are membranous. The true wings are straight and unplaited, Some feed on vegetable and some on animal juices. Those having the upper wings of a uniform substance throughout (whether leathery or transparent) have been constituted into a section, and by some naturalists into an order named Homoptera; those having them partly leathery and partly transparent constitute the section or order Heteroptera. To the Hemiptera belong the plant-lice, boat-fly, cochineal insect, locust, bug, lantern-fly, etc. Research Hemiptera
Carmine is a brilliant, deep, fiery red colouring derived from the cochineal insect. It was first prepared by a Franciscanmonk at Pisa and manufacture began in 1650. Carmine is used as an artists' colour and as a glass colour, works well with water and oil, but fades badly. Research Carmine
Red is one of the primary colours. It is the colour of the spectrum which is farthest away from violet. Red pigments are derived from cinnabar, realgar, cochineal and coal-tar.
Abbreviations
Research Cochineal
