Field's Chromatography Part 9

It is a good drier.

Mixed with Indian ink, it furnishes useful shadows; and compounded with cobalt or indigo, most serviceable grays. For sunsets, where deep purple lines are louring over the horizon's brink, a mixture of French blue with a little Indian red and lake is admirably adapted. In twilight and stormy clouds, in sails and buildings, in shade carnations of portraits and backgrounds, &c., the red is often employed.

84. LIGHT RED

Is an ochre of an orange-russet hue, chiefly valued for its tints. The princ.i.p.al yellow ochres afford this colour best, and the brighter and clearer the yellow ochre is from which it is prepared, the brighter will the red be, and the better flesh tints will it yield with white. Light red has the good properties common to ochres, dries capitally, and furnishes an excellent crayon. It is much used both in figure and landscape painting, giving fine grays with cobalt, and serviceable compounds with yellow ochre, indigo, lamp black, rose madder, Payne's grey, brown madder, &c.

Terra Puzzoli, a volcanic production, is a species of light red, as is the Carnagione of the Italians.

85. VENETIAN RED,

Less known as _English Red_, _Prussian Red_, and _Scarlet Ochre_. True Venetian red, that is, the red of the Venetians, was probably brought from India, and similar to our modern Indian red. The Venetian red of the present day, however, is an artificial product, containing no earthy base, and therefore improperly cla.s.sed among the ochres. It is prepared by calcining sulphate of iron, to which a little nitre may be advantageously added. The result is a peroxide of iron, resembling light red, but more powerful, and of a more scarlet hue. It is very permanent, but being a purely iron pigment, should be cautiously employed with colours affected by that metal. Though not bright, its tints are clear, and it mixes and works kindly with cobalt or French blue, affording fine pearly grays. Heightened by madder lake, it furnishes a glowing red, very useful in some descriptions of skies; and saddened by black, it gives low toned reds of good quality for buildings. With white it produces carnation tints nearly approaching to nature, and much employed by t.i.tian, Vand.y.k.e, and others. Compounded with aureolin, Venetian red yields a clear orange of considerable transparency.

_Spanish Red_ is an ochre differing little from the above.

86. PURE SCARLET,

Or _Iodine Scarlet_, is an iodide of mercury, having the body and opacity of vermilion, and being as much inferior to it in permanence as it is superior in brilliancy. Of all artistic pigments, it is at once the most dazzling and the most fugitive, and should have no place on the palette. If used, it should be with an ivory knife, as iron and most metals change it to colours varying from yellow to black; hence it should never be compounded with metallic pigments. So sensitive, indeed, is it to the slightest touch of metal, that it has been known to turn to a dull brown merely by being washed over with a colour which had been taken out of its saucer with a penknife. In the cake, it must be carefully kept wrapped up in paper, otherwise the presence of metal tubes or a knife in the colour-box may spoil it. By a foul atmosphere, the scarlet is soon utterly destroyed, and even metallized. In contact with the air, it quickly fades away; and has been found to vanish completely, when exposed to light alone. Employed in water, a thick glaze of gum-arabic or gamboge adds to its stability. As a landscape pigment, the colour is out of the general scale of nature; but in flower-painting its charms are almost irresistible. Nothing certainly can approach it as a colour for scarlet geraniums, but its beauty is almost as fleeting as the flowers.

87. RED CHROME,

Also called _Scarlet Chrome_, is a bright chromate of lead of an orange-red colour, the red being predominant. Rank in tone, it is liable to the changes of the yellow chromes, though in a less degree. The recent introduction of cadmium red renders the use of this unnecessary.

88. RED LEAD,

_Minium_, or _Saturnine Red_, is an ancient pigment, by some old writers confounded with cinnabar, and termed Sinoper or Synoper. It is an oxide of uncertain composition, prepared by subjecting ma.s.sicot to the heat of a furnace with an expanded surface and free accession of air. Of a scarlet colour and fine hue, it is warmer than common vermilion, whose body and opacity it possesses, and with which it was once customary to mix it. Bright, but not so vivid as the iodide of mercury, it is more durable, although far less so than vermilion. When pure and alone, light does not affect its colour, which soon flies, however, on being mixed with white lead or any preparation of that metal. By impure air, red lead is blackened and ultimately metallized.

On account of its extreme fugacity when compounded with white lead, this red cannot be used in tints; but employed, unmixed with other pigments, in simple varnish or oil not rendered drying by any metallic oxide, it may stand a long time under favourable circ.u.mstances. It is an excellent dryer in oil, and has often been used as a siccative with other colours, but it cannot safely be so employed except with the ochres, earths, and blacks in general. Oils, varnishes, and, in some measure, strong mucilages, are preventive of chemical action in the compounding of colours, by intervening and clothing the particles of pigments; and hence heterogeneous and injudicious tints and mixtures have sometimes stood well, but are not to be relied upon in practice. Altogether, red lead is a dangerous pigment in any but skilled hands, and has naturally had a variable character for permanence. It is frequently adulterated with earthy substances, such as brickdust, red ochre, and colcotha.

VERMILIONS.

Vermilion is so called from the Italian word _vermiglio_ (little worm,) given to the kermes or "coccus ilicis," which was used as a scarlet dye before the introduction of cochineal. It is a sulphuret of mercury, which previous to levigation is called Cinnabar; and is found native in quicksilver mines, as well as produced artificially. This is an ancient pigment, the [Greek: kinnabari] of the Greeks, and the _minium_--a term now confined to red lead--of older writers. Pliny states that it was so esteemed by the Romans, as to have its price fixed by express law of state. Among other places, the natural product is met with in California, Spain, and Peru; and in China there is a native cinnabar so pure as only to require grinding to become very perfect vermilion.

Whether the natural possesses any advantages over the artificial, appears to admit of doubt: Bouvier thought that the former blackened more than the latter, and others coincide with him. As, however, native vermilion has become commercially obsolete, the question of their comparative permanence is of little importance. Theoretically, it is difficult to a.s.sign a reason why there should be any difference between the two.

Vermilion is capable of being made by both wet and dry processes, but the last are almost exclusively adopted on a scale, and are, we believe, preferable. Our opinion, expressed with some diffidence, is, that pigments whose colour depends on the union of sulphur with a metal--such as vermilion and cadmium yellow--are more stable when the sulphur is forced to bite into the base. This can only be effected by a considerable degree of heat, far greater than can be obtained in any moist method. We hold that in pigments so produced, the sulphur is less liable to oxidation by air and light, and that therefore the colour better withstands exposure to those agents. Before now, vermilions have been taxed with fading in a strong light: supposing them genuine, it would be interesting to know by what mode they were manufactured.

There are two kinds of vermilion in common use, European and Chinese, of which the first inclines to orange and the second to purple. These include the several varieties known as--_Vermilion_, _Deep Vermilion_, _Pale Vermilion_, _Scarlet Vermilion_, _Chinese Vermilion_, _Carmine Vermilion_, _Extract of Vermilion_, _Orange Vermilion_, and _Field's Orange Vermilion_.

89. VERMILION,

Deep or pale, when well made and pure is of strict permanence, not sensibly affected by light, time, or foul air; and eligible either in water, oil, or fresco. For an enamel colour it is unsuited, being dissipated at a red heat, a test that detects the presence of any non-volatile adulterant. The best vermilion is a powerful vivid colour, higher in tone than all reds, except the scarlet iodide of mercury. With this it should not be compounded, but with other pigments it may safely be used in admixture, as far as its own colour is concerned. Of great body, weight, and opacity, it is a somewhat slow drier; and does not retain that brilliancy when dry, which is peculiar to it while wet. A want of transparency, and not drying well, prevent its being so generally employed as would be desirable. Pictures should seem to be painted with colour, not with pigment, the material being lost amid the hues, tints, and shades; but with such compounds as vermilion, the art of concealing art becomes difficult indeed. The pigment is apt to predominate over the colour, and the painting to look mechanical rather than natural: particles are apparent where hues alone should be seen, and all sense of reality is destroyed. For these reasons, vermilion is a dangerous pigment in unskilled hands, needing an intimate acquaintance with its physical properties. The extreme weight or specific gravity of the red renders it liable to sink and separate when compounded with other colours; hence the heavier those mixed with it the better. Its almost equal opacity, too, and habit of washing up, militate against its use by young painters. With experience, however, and due care, this is a serviceable colour; yielding with white most delicate flesh tints, and in minute proportion with cobalt or French blue and white, tender aerial grays.

Being cheaper than formerly, vermilion is not so much adulterated as it once was; although, even now, brickdust, orpiment, &c. sometimes sophisticate it. The knavish practices to which the pigment has been subjected, have acquired it an ill-fame both with authors and artists.

Vermilion has been charged with fading in the light, and with being blackened by impure air; but it was the custom to crimson the colour by means of lake, or tone it to a scarlet hue by red lead. With pigments as with persons, evil communications corrupt good manners--a motto that might be written with advantage on every palette.

90. SCARLET VERMILION

Resembles the preceding in all respects, except in being more scarlet in its tint, and washing better; advantages which render it more useful when the tone is required to be very bright and pure. At one time, the Dutch alone in Europe possessed the secret of giving to vermilion a rich scarlet colour.

91. CHINESE VERMILION,

Or _Carmine Vermilion_, partakes of a crimson hue, and is adapted, mixed with white, for the rose and lilac-tints of some complexions. Like other vermilions, however, the colour needs much nicety of management; and it must not be attempted to further enrich it by admixture of cochineal lakes. Those colours, as we have remarked, cannot safely be brought into contact with vermilion, either compounded or as a glaze.

The reds of madder should be subst.i.tuted for them.

92. EXTRACT OF VERMILION,

A somewhat curious name for a metallic colour, was a peculiar preparation of the author, possessing in its time certain advantages over other vermilions, and especially distinguished by a more scarlet hue. Now, however, extract of vermilion and scarlet vermilion are synonymous terms.

93. ORANGE VERMILION

Is rather more transparent than ordinary vermilion, with a clear but not bright orange hue. It also washes better, and is for landscape purposes more generally useful. Resembling red-lead in appearance, it is not subject to its changes, being perfectly durable in oil and water. A most powerful tinger of white, its tints are warmer than red-lead's, affording delicate carnations similar to those of t.i.tian and Rubens.

This pigment--or, preferably, the succeeding variety--may be employed with excellent results in sc.u.mbling of flesh, for which Sir Joshua Reynolds improperly used the so-called red orpiment. It dries in simple linseed oil, but works with best effect in water with a considerable portion of gum. In speaking of sunset and sunrise clouds, Mr. Penley observes--"Orange vermilion if used so thin as to get rid of its opacity, is a fine tone; but it must be remembered that _transparency_ is the character of the sunset or sunrise, and hence arises the difficulty of employing such opaque colour effectively." Before the introduction of cadmium red, this and the following pigment were the best and only unexceptionable orange-reds known. It is probable, however, that the new colour will in a great measure supersede these latter in cases where transparency is sought. Orange vermilion is often a mixture, in which case the yellow employed is apt to separate from the red and float on its surface.

94. FIELD'S ORANGE VERMILION

Is a superior preparation to the preceding, being brighter, purer, and clearer. It possesses also, less opacity, and is not a compound. Both pigments are rather reds with an orange cast than strictly orange colours, and are therefore inserted in this chapter.

95. _Antimony Red_,

Or Mineral Kermes. We have obtained this colour ranging from light orange to deep carmine, of different degrees of brightness and stability. Some of the tints stood well in a book, but faded on exposure to light and air; and some even vanished when secluded from those agents. It has more than once been recommended as a pigment, but our experience is against its adoption by artists. The colour is not affected by sulphuretted hydrogen.

96. _Chica Red_

Is extracted from the leaves of a tree growing in central and southern America. A sample examined by Mr. O'Neill was in small irregular lumps, of a bright scarlet colour, adherent to the tongue like indigo, and taking a metallic polish of a greenish reflection, when rubbed against a hard smooth body, as the finger nail. So far it seems to be only employed by the Indians as a paint for their bodies, mixed up with fatty matters. It has doubtless been used in painting: for in the old churches of those parts of America there is a good deal of red colour, which remains brilliant and sound after a couple of centuries; and from the appearance of it, and such accounts as can be collected, it is probably this chica. A portion was forwarded to an eminent artist in England, to ascertain whether it would be of any value as a pigment in the fine arts. His report is stated to have been unfavourable; and the chica, contained in a gourd labelled "Chica d'Andiguez," was then tested as to its capabilities for dyeing and printing. Fine and durable reds were found to be produced by it upon woollen, equal to those of cochineal. To mordanted calico the shades imparted were dull and heavy, but very solid. Chica is described as a very strong colouring matter, a small quant.i.ty dyeing a large amount of cloth, and as more nearly resembling lac lake than anything else.

No information existing as to its price, or the quant.i.ty that could be obtained if it were wanted, chica remains in the state of an unapplied product. If it really possess, however, the durability a.s.signed to it, this red is worth attention. With regard to the artist's disapproval, the chica sent him may not have been properly or sufficiently prepared to adapt it for a pigment.

97. _Coal-Tar Colours._

Our work might be considered incomplete without some allusion to the coal-tar colours, even though they are rather dyes than pigments, not possessing sufficient stability for the palette. To avoid repeated reference, we have preferred grouping them in this chapter, irrespective of hue. Consequently, yellow, red, blue, orange, green, purple, brown, and black, will be all comprised under the heading of coal-tar colours.

Previous to the year 1856 the colouring matters derived from coal-tar were practically unknown. Until then, that black evil-smelling substance was looked upon as almost worthless; but gradually the unsightly grub emerged into a beautiful b.u.t.terfly, clothed first in mauve and next in magenta. After its long winter of neglect, there sprung from coal-tar the most vivid and varied hues, like flowers from the earth at spring.

At a touch of the fairy wand of science, the waste land became a garden of tropic tints, and colour succeeded colour, until the whole gamut had been gone through. Never was transformation more dazzling or more complete. The once despised refuse was now a valued commercial product--indeed a trade in itself. Perfectly fascinated by the study, chemists threw themselves heart and soul into coal-tar, and coal-tar colours were to be seen everywhere.

It were beside our purpose to enter into the various stages through which coal has to pa.s.s to become colour. Enough to state that to the introduction of gas-light we are indebted for the acquisition of coal-tar colours, the starting point for the production of mauve, magenta, &c., being the manufacture of coal-gas. From the destructive distillation of coal, coal-tar oil results; and from this are obtained the products which yield the colours in question. Among these products may be mentioned aniline, rosaniline, napthaline, chinoline, carbolic acid, picric acid, &c., with their derivatives.

Of the fifty-one compounds furnished by the distillation of coal, perhaps the most popularly a.s.sociated with coal-tar colours is aniline, to which we will therefore confine ourselves. Discovered in 1826, this body was formerly prepared from indigo--in Spanish, _anil_, whence the name; but is now produced on a larger scale from benzol, a coal-tar product. As the source of mauve and magenta, aniline must be considered the parent of coal-tar colours generally. Little was known of it at one time except that on being mixed with a solution of chloride of lime there was formed a splendid purple liquid, which immediately gave place to a dingy reddish precipitate. From the investigation of this simple fact, however, by Mr. W. Perkin, there was created a new and important branch of chemical industry--the manufacture of coal-tar colours. The violet mauve led the way, followed by the red magenta, the blue azuline, the yellow phosphine, the green emeraldine, the orange aurine, by purple, and brown, and black. Such were the hues, with many intermediate tints and shades, which one reaction brought forth. The world rubbed its eyes with astonishment; and truly it seemed almost as wonderful to produce the colours of the rainbow from a lump of coal, as to extract sunshine from cuc.u.mbers.

The history of these colours reads more like a romance than a sober story, but to the artist it is of slight practical interest.

Sufficiently stable as dyes, though they be, coal-tar colours are not adapted to the palette. Mauve, magenta, with a few others, hare been introduced as pigments and fairly tried, but a want of permanence has been fatal to their success. Mauve is more durable than magenta, and the rest vary in stability, but none of them have proved really fitted for artists' colours. Exposed to light and air, they all more or less fade, especially in thin washes; and they have mostly the objection of staining and permeating the paper or canvas on which they are employed.

Used in body, some may be found eligible in portfolio illuminations and the like, where the brilliancy of their colours shows to advantage; but in landscapes and pictures of life, coal-tar pigments are best avoided.

Cakes of red, blue, violet, and other hues, may be prepared for painting, by combining the colours with a mixture of starch and alumina, or with soap and alumina in a moist state--thus: 150 parts of white curd soap, dissolved in 1000 parts of hot water, are mixed with an alcoholic or a methylated spirit solution of six parts of the crystallized or solid coal-tar colour. To this are added 250 parts by weight of washed gelatinous alumina. The whole is then well stirred, collected on a filter, drained, and dried. Several hues, tints, and shades may be obtained by compounding: for instance, an orange is produced on admixture of picric yellow with aniline red, or a green by adding the same yellow to aniline blue.

98. _Cobalt Reds._