Field's Chromatography Part 8

69. CARMINE.

A name once given only to the fine feculences of kermes and cochineal tinctures, now denotes generally any pigment which resembles them in beauty, richness of hue, and powdery texture. We have, therefore, blue and other coloured carmines, though the term is usually confined to the crimson and scarlet lakes of cochineal. As at present commonly understood, carmine is that preparation of cochineal which contains the most colouring matter and the least aluminous base. Hence it is the richest, deepest, most intense, and most permanent. Although not to be cla.s.sed as durable, yet by reason of its extreme depth, carmine is more stable than the weaker crimson, scarlet, and purple lakes. When well-made, pure, and employed alone and in body, it has been known to retain its colour for years, especially if protected by oil or varnish.

In tint with white lead, however, it has no stability; and though little affected by impure air, in glazing it is soon discoloured and destroyed by the action of light. Of great power in its full touches, it possesses considerable clearness in the pale washes, and works admirably. In landscape, carmine is seldom used, the colour being chiefly valued in flower painting and illumination.

It has been erroneously stated that the finest carmines cannot be made in England, owing to a want of clearness in the atmosphere and a scarcity of sunshine. For many years, however, they have been produced in this country, not only finer than any foreign preparations, but equally good in winter as in summer.

Carmine is sometimes sophisticated with starch, vermilion, and with alumina not formed in the process of manufacture. Occasionally also, a portion of the animal matter of the cochineal from which it has been obtained is left mixed with it. These accidental or intentional impurities may mostly be detected by heating the carmine with liquid ammonia, which entirely dissolves the colouring matter and leaves the impurities in an insoluble state.

70. CRIMSON LAKE

Is a cochineal pigment containing more aluminous base than carmine, and is consequently weaker in colour and less stable. Deficient in much of the depth and brilliancy which belong to the latter, it is more commonly employed and more generally useful. This lake is of service in mixing tints, to impart richness, in flower painting and illumination, and is, like all cochineal colours, of greater utility in water than in oil.

With cobalt and gamboge it yields an excellent gray, and with cobalt alone a fine purple for heather. Distant hills may be strengthened with a tint of French blue and lake, and Vand.y.k.e brown with the crimson will be found admirable for a rich coloured foreground. Many other beautiful tints, unexceptionable in an artistic sense, are afforded by crimson lake on admixture. It should be remembered, however, that not one of them is permanent as far as the lake is concerned. All cochineal pigments are more or less affected by strong light, which weakens their tints, and in time deprives them of colour; and it is not by being compounded that a fugitive colour is rendered durable.

71. SCARLET LAKE

Is prepared in the form of drops from cochineal, and is of a fine transparent red colour and excellent body, though, like other lakes, it dries slowly. Discoloured and destroyed by strong light both in water and oil, and not permanent in tint with white lead or in combination with other pigments, it possesses the common attributes of cochineal lakes. Yet when well prepared, used in sufficient body, and not unduly exposed, it has been found to last a lengthened period; but it ought never to be employed in glazing, nor at all in works that aim at high reputation and stability. It is in general tinted with vermilion, which has probably been mixed with lakes at all times to give their scarlet hue and add to their weight; for upon examining with a powerful lens some fine pictures of ancient masters, in which lake had been used in glazing, particles of vermilion were apparent, from which lake had evidently flown. Unfortunately, these lakes are injured by vermilion as they are by lead, so that glazings of cochineal over vermilion or lead are particularly apt to vanish. This effect is very remarkable in several pictures of Cuyp, where he has introduced a figure in red from which the shadows have disappeared, owing to their having been formed with lake over vermilion. The scarlet hue of this lake should properly be imparted to it during the process of manufacture, and not by subsequent mechanical admixture.

72. PURPLE LAKE

Is a species of crimson lake with a purple cast, transparent and deep-toned, and useful in shadows: in other respects resembling that pigment. Red being its predominant colour, we have preferred cla.s.sing this so-called purple among the reds, in spite of its name. On the whole it is more durable than crimson lake.

73. FLORENTINE LAKE

Differs from scarlet lake only in the mode of preparation. Formerly the lake so called was extracted from the shreds of scarlet cloth. The same may be said of _Chinese Lake_.

74. HAMBURGH LAKE

Is a lake of great power and depth of colour, purplish or inclining to crimson, which dries with extreme difficulty, but differs in no other essential respect from preceding cochineal lakes--an observation which applies to _Roman Lake_, _Venetian Lake_, and many others; none of which, however beautiful or reputed, is ent.i.tled to the character of stability either in hue, shade, or tint.

75. DRAGON'S BLOOD

Is a resin brought from the East Indies. It is of a warm semi-transparent, rather dull red colour, which is deepened by impure air, and darkened by light. There are two or three sorts, but that in drops is the best. White lead soon destroys it, and in oil it dries with extreme difficulty. It is sometimes used to colour varnishes and lackers, being soluble in oils and alcohol. Although it has been recommended as a pigment, dragon's blood does not merit the attention of the artist.

76. INDIAN LAKE,

Likewise called _Lac Lake_. This is obtained from the lac or lacca of India, a resinous secretion which seems to depend upon the puncture of a small insect--_coccus ficus_--made for the sake of depositing its ova on the branches of several plants, found in Siam, a.s.sam, and Bengal. The twigs soon become encrusted with a mammelated substance of a red colour more or less deep, nearly transparent, hard, and having a brilliant conchoidal fracture. The roughly-prepared coating is imported in two forms, called lac-lake and lac-dye, which contain about 50 per cent of colouring matter, combined with more or less resin, and with earthy matters, consisting chiefly of carbonate and sulphate of lime and silica.

Indian lake is rich, transparent, and deep,--less brilliant and more durable than the colours of cochineal, but inferior in both respects to those of madder. Used thickly or in strong glazing, as a shadow colour, it is of great body and much permanence; but in thin glazing it changes and flies, as it also does in tint with white lead. In the properties of drying, &c., it resembles other lakes. The pigment may be dispensed with in favour of madder lake and madder brown, whose combinations serve for every purpose to which it can be applied, and are stable.

Lac appears to be the lake which has stood best in old pictures, and was probably employed by the Venetians, who had the trade of India when painting flourished at Venice.

MADDER LAKES.

_Rubric Lakes_, or _Field's Lakes_, are derived from the root of "rubia tinctorum," a plant largely grown in France and Holland, whence the bulk of that used in England is obtained. The French madders are in a state of very fine powder, containing one half their weight of gum, sugar, salts, and other soluble substances, which water speedily dissolves.

Madder roots in the unground state are imported from the Levant, and called Turkey roots. Good qualities of Turkey madder yield near sixty per cent of extractive matters, a term that includes everything removable by water and dilute alkalis: the woody fibre is therefore about forty per cent. This is presuming the root to be genuine, for madder is often adulterated with brickdust, red ochre, red sand, clay, mahogany sawdust, logwood, sandal and j.a.pan-wood, and bran.

Unlike cochineal, madder possesses several colouring matters; the question of which, despite the learned researches of Dr. Schunck and others, is far from settled yet. The following remarks embody our own experience of the root, simply as a pigment-producing product:--

Madder contains five colouring matters--yellow, red, orange, purple, and brown. Of these, the first colour is soluble in cold water. By washing the powdered root quickly with it by decantation, the yellow and brown are extracted in the form of an opaque liquid. If this be decanted and allowed to stand, the brown deposits, leaving a clear buffish-yellow supernatant liquor. In the root from which the extract was poured, the remaining three colours are left. On adding a strong boiling solution of alum, these are dissolved, yielding a fine red liquid. From this there can be thrown down, by the agency of different chemicals, a red, an orange, or a purple precipitate. Or, supposing the whole of the colouring matter to be deposited as a red lake, it is possible to convert this--also by the agency of different chemicals--either into orange or purple. Hence, for all practical purposes, madder contains but three colouring matters: a yellow, soluble in cold water; a brown, not soluble in, but capable of being extracted by cold water; and a red, soluble in boiling alum, and furnishing at will a purple or an orange.

As was observed in the previous chapter, no good pigment is obtained from the yellow, of which the less there is present the better; but the brown affords a valued product, which will be duly noticed. It is essential to the purity of the reds, that the madder should be freed from both these colours; and it was probably due to insufficient aqueous washing of the root, that the old lakes were dull and muddy, mere brick-reds of ochrous hues. For many years, however, lakes have been prepared perfectly transparent, and literally as beautiful and pure in colour as the rose; qualities in which they are unrivalled by the lakes and carmine of cochineal. They have justly been considered as supplying a desideratum, and as among the most valuable acquisitions of the palette in modern times, since permanent transparent red and rose pigments were previously unknown. The red varieties range from rich crimson to a delicate rose, and are known as _Madder Carmine_, _Field's Carmine_, _Pink Madder_, _Rose Madder_, _Madder Lake_, and _Liquid Rubiate_ or _Liquid Madder Lake_.

77. MADDER CARMINE,

Or _Field's Carmine_, like that of cochineal, is the richest and deepest lake prepared, containing most colouring matter and least base. It differs from the paler products chiefly in transparency and intensity, and is the only durable carmine for painting either in water or oil; for both which it is qualified by texture without previous grinding. In common with the other reds of madder, its faint washes possess greater clearness than those of cochineal. This carmine is a difficult colour to make well, exceeding care and nicety being required to obtain the fullest tint: hence it is apt to vary in hue according to the skill of the manufacturer. Being expensive also, the price increasing according to depth of colour, the lake has been the most liable to adulteration, of all the reds of madder. Merimee states that samples were sent to him from Berlin, under the name of "carmine madder," which evidently owed their brightness to tincture of cochineal. It is certain that madder lakes have been imitated on the Continent with various success by those of lac, cochineal, and carthamus or safflower. The best we have seen is the _laque de garance_, which was tinged with the rouge of carthamus, and was of course inferior in durability. As, however, liquid ammonia and alkalis generally dissolve the colours of cochineal, lac, and safflower, the test is simple. If the liquid remain uncoloured on adding ammonia to an a.s.sumed madder lake, in all probability the pigment is genuine.

78. ROSE MADDER.

The exquisite flowers of Bartholomew, Miss Mutrie, and others, give evidence of the beauty, purity, and stability of the reds of madder, both in water and oil. This variety, less intense than the preceding and without its carmine hue, is of a rich rose colour--a true rose--tending neither to crimson, scarlet, nor purple. Marked by a peculiar softness, and an unusual clearness in its pale washes, rose madder affords the most perfect carnation tints known. Not liable to change by the action of light, impure air, or admixture with white lead and other colours, it resembles all madder lakes in these respects. Like them, too, it is but a tardy dryer in oil unless thoroughly edulcorated, and does not work in water with the entire fulness and facility of cochineal pigments. When, therefore, permanence is of no consideration, the latter may still be preferred. In those works, however, where the hues and tints of nature are to be imitated with stability and pure effect, the rose colours of madder are become indispensable. They have this advantage, moreover, that they possess the property of ultramarine of improving in hue by time--their tendency being to their own specific prismatic red colour.

As they are too beautiful and require saddening for the general use of the painter, the addition of manganese brown, cappagh brown, or burnt umber, adds to their powers, and improves their drying in oils; for which last purpose a little j.a.panner's gold size may be likewise employed.

In the light touches of bright clouds or mountains, where a mixture of cadmium yellow and Chinese white is used, rose madder is invaluable for glazing over such touches when dry, should they be required of a warmer hue. The red portion of sunset skies may be improved by a thin wash of this pigment, tinged perhaps with the above yellow, or with gamboge.

Most serviceable landscape tints are afforded by admixture of rose madder with cobalt, Indian red, purple madder, yellow ochre, lamp black, &c. In painting flesh, the lake cannot be dispensed with.

79. PINK MADDER

Was a weaker preparation of the preceding, paler in hue and possessing less colour. It was formerly employed in miniature painting, but with the decline of that art became less and less used, until it may now be said to be obsolete. The name, however, still lives, but is applied to rose madder, which is indeed indifferently called _Rose Madder_, _Pink Madder_, or _Madder Lake_. Speaking of pink roses, Mrs. Duffield remarks that "the local colour is best imitated with pink madder," and the Messrs. Rowbotham observe "this heather may be best represented by cobalt and madder lake." In trade catalogues several names are often given, as in this instance, to one and the same pigment. The seeming superfluity is rendered necessary through some artists knowing a pigment by one name and some by another. Hence arises the value of a list of synonyms.

80. LIQUID RUBIATE,

_Rose Rubiate_, or _Liquid Madder Lake_, is a concentrated tincture of madder of the most beautiful and perfect rose colour and transparency.

It is used as a water colour only in its simple state, diluted with water, and with or without gum. In oil it dries by acting as a siccative. Mixed or ground with all other madder colours, with or without gum, it forms combinations which work freely in water, and produce the most charming and stable effects. The rubiate also furnishes a fine red ink, and is a durable stain for printing on cotton, &c. To the tinting of maps and charts permanently, it is peculiarly suited.

81. MARS RED

Or _Rouge de Mars_, is an artificial iron ochre, similar in subdued tint and permanence to the native earths. Its chemical affinities, however, are greater than those of the latter, and it therefore requires to be employed cautiously with pigments affected by iron. In this respect the red resembles its compeers, Mars yellow, Mars orange, Mars violet, and Mars brown, all of which are iron ochres artificially prepared.

Possessing the richness and depth of Indian red, it is distinguished by the russet-orange hue of light red. Its pale washes are marked by considerable clearness. In keeping the Mars colours separate from the ochres, we have followed the plan of the author.

OCHRES

Comprise _Red Ochre_, _Indian Red_, _Light Red_, _Venetian Red_, _English Red_, _Persian Red_, _Prussian Red_, _Spanish Red_, _Brown Red_, _Indian Ochre_, _Scarlet Ochre_, _Carnagione_, _Terra Puzzoli_, _English Vermilion_, _Spanish Brown_, _Majolica_, _Redding_, _Ruddle_, _Bole_, _Almagra_, _Sil Attic.u.m_, _Terra Sinopica_, &c. They are rather hues and tints than definite colours, or more properly belong to the tertiary, semi-neutral, and broken colours. As a rule they are native pigments, found in most countries, and very abundantly and fine in our own; but some are products of manufacture, and obtainable in the variety of nature by art.

The colouring matter of these earths is the red oxide of iron, as that of the yellow ochres is the yellow oxide. All the yellow ochres are more or less reddened by being burnt, as yellow oxide of iron itself becomes red on calcination. It was observed in the fourth chapter that time has often the effect of fire, more or less intense; and hence it is that yellow ochres occasionally a.s.sume a buffish-red hue, by the gradual peroxidation of the iron. Similarly, if a yellow ochre be but partially calcined, the red so obtained is apt to deepen or darken. Especially do these changes take place when the iron oxides are not a.s.sociated with an earthy base; when, in fact, the so-called ochres cannot be cla.s.sed as such. In this case, too, as was lately remarked, the pigments are more chemically active, and more likely to affect those colours to which iron is inimical.

82. RED OCHRE

Is a native earth; sometimes brown ochre burnt, and called _Brown Red_.

It is less pure in hue and clear in its tints than light red, and is best reserved for dark and vigorous shades and touches. For draperies of a dusky red it is well suited, or even for the shadows of bright-red drapery. In dead colouring it is very valuable. Like all ochres, it is characterized by permanence in water, oil, crayons, and fresco; and is, like most of them, available in enamel-painting.

Almagra, the Sil Attic.u.m of the ancients, is a deep red ochre found in Andalusia; as is also their Terra Sinopica or Armenian Bole, dug originally in Cappadocia, and now found in New Jersey and elsewhere under the name of Bloodstone.

83. INDIAN RED,

Once known as _Persian Red_, is brought from Bengal. It is a natural earth rich in peroxide of iron, of a purple russet hue and good body, and valued when fine for the clearness and soft lakey tone of its tints.

In a crude state it is a coa.r.s.e powder, full of extremely hard and brilliant particles of a dark appearance and sometimes magnetic. It is greatly improved by grinding and washing over, and is very permanent.

Neither light, impure air, mixture with other colours, time, nor fire, effects any sensible change in it; but being opaque and not keeping its place well, it is unsuited for glazing. This pigment differs considerably in its hues, that which is most rosy being esteemed the best, and affording the purest tints. Inferior ochres were formerly subst.i.tuted for Indian red, which procured it a variable character; but the colour being now obtained abundantly can in general be had genuine.