Field's Chromatography Part 24

" = " + Citrine} " = 2 Yellow + Red + Blue " = 2 Orange + Green + Purple " = 2 Citrine + Russet + Olive Marrone = Black + Red " = " + Purple-red " = " + Russet " = 2 Red } " = 2 Purple-red} + Dark Brown or Black " = 2 Russet } Gray = Black + Blue } " = " + Purple-blue} + 2 White " = " + Olive } " = 2 Blue } " = 2 Purple-blue} + Light Brown, or Black + 2 White " = 2 Olive }

In the last division, the White has been added to remind the reader that grays are coloured greys, not coloured blacks; and are therefore faint of hue. This paleness, however, need not necessarily be produced by admixture with white: it can be gained by means of thin washes. As a pigment, gray may be to all appearance black in bulk.

285. NEUTRAL TINT,

or, more correctly, _Semi_-Neutral Tint, is a compound shadow colour of a cool character. It is permanent, except that on exposure the gray is apt to become grey, a change which may be prevented by a slight addition of ultramarine ash. So protected, it becomes serviceable in landscape for the extreme distance, which, it may be laid down as a general principle, should be painted rather cold than otherwise. Blue being the princ.i.p.al compound of atmosphere, it is of the utmost importance to obtain this in the first instance, particularly as, from its being only of a blue tint, not blue colour, it is so immediately altered and acted upon by subsequent washes; whereas, the blue tone once lost, it will be found very difficult to be recovered. Wherever a picture is wanting in air effect, the cause will, upon examination, be seen to rest entirely upon the absence of pure grays, bordering upon a bluish tone, not tending, be it observed, to brown or purple. A bluish gray, then, of rather a cold tone, such as the neutral tint, is recommended as the prevailing hue with which to begin the extreme distances; and, as a rule, it is better to pa.s.s with this over as much of the landscape as possible, and thus lay the foundation for a general atmosphere.

286. PAYNE'S GRAY

resembles the preceding in being a compound colour and liable to a.s.sume a grey cast by time, but differs from it in having more lilac in its hue, and being therefore of a warmer tone. Giving by itself a clear violet shadow, it may be rendered more neutral by a small portion of burnt Sienna, an admixture which, whether the gray or Sienna predominates, affords useful tints. Compounded with light red or Vand.y.k.e brown, the gray is good for s.h.i.+pping and sails, or the stems and branches of trees; while with gamboge or aureolin it is suited to glossy leaves in high light, also to very cold tones in foregrounds, herbage, &c. Yellow ochre, light red, and Payne's gray form a mixture for banks and roads; the ochre, gray, and sepia, a most beautiful tint for stones; and brown madder and the gray, a fine shade for the black head and feet of cattle. Alone, the gray is serviceable for slate; and compounded with light red, for bricks or tiles in shadow.

287. ULTRAMARINE ASH

is obtained from the stone after the richer and more intense blue has been extracted. Although not equal in beauty, and inferior in strength of colour to ultramarine, it is a valuable bye-product varying in shade from light to dark, and in hue from pale azure to cold blue. With a grey cast, it affords delicate and extremely tender tints, not so positive as ultramarine, but which, as water-colours, wash much better. It furnishes grays softer, purer, and more suited to the pearly tints of flesh, skies, distances, foliage, shadows of drapery, &c. than those composed of other blues, with white and black, which the old masters were wont to employ. Ultramarine, however, produces the same effects when broken with black and white, and is thus sometimes carried throughout the colouring of a picture. The ash, compounded with lamp black, gives a soft cold gray for dark louring clouds, or for twilight away from the sun's influence. Alone it is adapted to very remote hills or mountains, and with orient yellow or aureolin to distant foliage.

The native phosphate of iron, which has been already described in the tenth chapter under its name of Blue Ochre, might have been cla.s.sed among the grays, being similar in colour to the deeper hues of ultramarine ashes. Powdered slate, slate clays, and several native earths, likewise rank with grays; but some of the earths we have tried are not durable, being apt to become brown by the oxidation of the iron they contain. It may be proper here to mention those other pigments, known as tints, which, being the result of the experience of accredited masters in their peculiar modes of practice, serve to facilitate the progress of their amateur pupils, while they are more or less eligible for artists. Such are _Harding's_ and _Macpherson's Tints_, composed of pigments which a.s.sociate cordially, and sold ready prepared in cakes and boxes for miniature and water painting.

Of the four grays in use--mineral gray, ultramarine ash, neutral tint, and Payne's gray--the two first are quite unchangeable, and the others sufficiently stable to be cla.s.sed as permanent.

CHAPTER XX.

ON THE NEUTRAL, GREY.

Grey is the second and intermediate of the neutral colours, standing between _white_ and _black_. True or normal grey is only obtainable by admixture of pure white with pure black, various proportions of which afford numerous tones of pure grey. In practice it may likewise be produced by a thin wash of black over white. The neutral gr_e_y differs from the semi-neutral gr_a_y in not being coloured by any primary, secondary, tertiary, or semi-neutral; hence any blue, purple, olive, or gray added to it, at once destroys the neutrality of grey, and converts it into gray. Thus easily defiled and changed in cla.s.s, grey is rather a theoretical than a practical colour. To our knowledge, there has never been a true grey pigment, that is, one composed exclusively of pure white and pure black; the gr_a_ys known to the palette as Mineral Grey and Payne's Grey having been incorrectly named. Practically, the nearest approach to a normal grey is furnished by Black Lead, which forms grey tints of greater permanence and purity than the blacks in general use, and is now employed for this purpose with approved satisfaction by experienced artists.

Being compounded of white and black, grey partakes in some measure of the qualities of both those colours--for colours, as a matter of convenience, they must be called; although white is often spoken of as no colour, and black as the complete extinction of all colour. With white predominant, grey is used, pure or coloured, for the general lights of a picture; just as, with black predominant, grey is employed, pure or coloured, for the shades. It helps to subdue the absolute white, and to make the absolute black conspicuous. Black and white are in some respects complementary to each other, and when in contact, appear to differ more from each other than when viewed separately: both show with best effect when harmonised by a medium of grey, normal or otherwise.

The primary colours, also, gain in brilliancy and purity by the proximity of grey. With dark colours, such as blue and violet, and deep tones in general, grey forms a.s.sortments of a.n.a.logous harmonies; while with the luminous colours, such as red, orange, yellow, and the light tints of green, it forms harmonies of contrast. Although grey never produces a bad effect in its a.s.sortments with two luminous colours, in most cases the a.s.sociation is dull and inferior to black and white. The only instance in which grey a.s.sociates with two such colours more happily than white is that with red and orange. Grey is inferior to both white and black with red and green, red and yellow, orange and yellow, orange and green, yellow and green; and is not so good as white with yellow and blue. In a.s.sociation with sombre colours, such as blue and violet, and with broken tones of luminous colours, grey gives rise to harmonies of a.n.a.logy which have not the vigour of those with white; but if the colours do not combine well together, it has the advantage of separating them from each other. a.s.sociated with two colours, one sombre, the other luminous, grey will perhaps be better than white, if white produces too strong a contrast of tone: on the other hand, grey will be preferable to black, if that has the inconvenience of increasing too much the proportion of sombre colours. Grey a.s.sociates more happily than black with orange and violet, green and blue, or green and violet.

288. MIXED GREY.

When a ray of solar light (a sunbeam) is pa.s.sed through a prism of flint gla.s.s, and the image or 'prismatic spectrum' received upon a screen of white paper, it is found to consist of numerous rays of different colours, which are conveniently divided into six groups--red, orange, yellow, green, blue, violet. Optically, the union of red, yellow, and blue, in proper proportions, const.i.tutes white light; whether the rays of the three separate colours are mixed, or of one with the other two in combination: the same result ensues when red is mixed with green as if it were mixed with blue and yellow, because green is composed of blue and yellow. Consequently, any primary mixed with a secondary composed of the other two primaries, forms the complement of rays necessary to const.i.tute or make up white light, and vice versa.

There is, however, a very great difference between the results arising from the mixture of the pure coloured rays of the spectrum, and those from material colours or pigments. When, by means of a convex lens, we reunite the coloured rays of the spectrum white light is reproduced; but when we mix coloured materials, blues, yellows, and reds, the compound is never white, but grey or black; even if these coloured pigments are taken in the exact proportions in which their colours exist in the spectrum. Ultramarine, our purest blue, reflects red rays as well as blue rays; aureolin, our purest yellow, reflects blue as well as yellow rays; and carmine reflects yellow as well as red rays. Now whenever the third primary colour is present in any mixture of coloured materials, it tends to form grey, by mixing with a sufficient quant.i.ty of the other coloured rays to neutralize it, and the presence of this grey breaks or tarnishes the pure colour. Hence it is that to obtain a pure green, a blue should be taken tinged with yellow rather than with red, and a yellow tinged with blue: if there were chosen either a blue or a yellow tinged with red, this latter colour would go to form some grey in the compound, which would tarnish the green. In like manner, to produce pure orange, neither the red nor the yellow must contain blue; and similarly with pure purple, neither the blue nor red should contain yellow.

As regards pigments, then, a proper mixture of yellow, red, and blue; or of yellow and purple, red and green, or blue and orange; or of orange, green, and purple, affords black if sufficiently intense, and grey if sufficiently diluted. The black may be rendered grey by spreading a thin wash over a white ground, or by the direct addition of white. It must be remembered, however, that suitable proportions of the component colours are essential. When all three of the primaries, for example, are mixed together, colour is neutralised according as they are compounded of equal strength and in right quant.i.ties: if proper proportions are observed, pure black or normal grey results; but if not, there will be produced a coloured black or a coloured grey, an excess of one or two of the primaries giving rise to brown, marrone, or gray.

A reference to the lists of permanent primary and secondary pigments will show to what extent durable greys can be compounded. As these pigments differ so widely in hue and other properties, no fixed rules can be given for their admixture: to ensure neutrality, practice and a correct eye are indispensable. Without perfect neutrality, difficult to attain and rarely to be met with, grey ceases to exist. In pure white, pure grey, and pure black, colour is, so to speak, conspicuous by its absence.

CHAPTER XXI.

ON THE NEUTRAL, BLACK.

Black is the last and lowest in the series or scale of colours descending--the opposite extreme from white--the maximum of colour. To be perfect, it must be neutral with respect to colours individually, and absolutely transparent, or dest.i.tute of reflective power as regards light; its use in painting being to represent shade or depths, of which black is the element in a picture and in colours, as white is of light.

As there is no perfectly pure and transparent black pigment, black deteriorates all colours in deepening them, as it does warm colours by partially neutralizing them, but it combines less injuriously with cold colours. Though black is the antagonist of white, yet added to it in minute portion, it in general renders white more neutral, solid, and local, with less of the character of light. Impure black is brown, but black in its purity is a cold colour, and communicates a coolness to all light colours; thus it _blues_ white, _greens_ yellow, _purples_ red, and _cools_ blue. Hence the artist errs with ill effect who regards black as of nearest affinity to hot and brown colours, and will do well to keep in mind--"The glow of suns.h.i.+ne and the _cool_ of shade."

It is a fault of even some of our best colourists, as evinced by their pictures, to be too fond of black upon their palettes, and thence to infuse it needlessly into their tints and colours. With such it is a taste acquired from the study of old pictures; but in nature hardly any object above ground is black, or in daylight is rendered neutral thereby. Black, therefore, should be reserved for a local colour, or employed only in the under-painting properly called grounding and dead colouring. As a local colour, black has the effect of connecting or ama.s.sing surrounding objects, and is the most retiring of all colours, a property which it communicates to other colours in mixture. It heightens the effect of warm as well as light colours, by a double contrast when opposed to them, and in like manner subdues that of cold and deep colours. In mixture or glazing, however, these effects are reversed, by reason of the predominance of cold colour in the const.i.tution of black.

Having, therefore, the double office of colour and of shade, black is perhaps the most important of all colours to the artist, both as to its use and avoidance.

It may be laid down as a rule that the black must be conspicuous.

However small a point of black may be, it ought to catch the eye, otherwise the work is too heavy in the shadow. All the ordinary shadows should be of some _colour_--never black, nor approaching black, they should be evidently and always of a luminous nature, and the black should look strange among them; never occurring except in a black object, or in small points indicative of intense shade in the very centre of ma.s.ses of shadow. Shadows of absolutely negative grey, however, may be beautifully used with white, or with gold; but still though the black thus, in subdued strength, becomes s.p.a.cious, it should always be conspicuous: the spectator should notice this grey neutrality with some wonder, and enjoy, all the more intensely on account of it, the gold colour and the white which it relieves. Of all the great colourists, Velasquez is the greatest master of the black chords: his black is more precious than other people's crimson. Yet it is not simply black and white that must be made valuable, rare worth must be given to each colour employed; but the white and black ought to separate themselves quaintly from the rest, while the other colours should be continually pa.s.sing one into the other, being all plainly companions in the same gay world; while the white, black, and neutral grey should stand monkishly aloof in the midst of them. Crimson may be melted into purple, purple into blue, and blue into green, but none of them must be melted into black.

All colours are comprehended in the synthesis of black, consequently the whole sedative power of colour is comprised in black. It is the same in the synthesis of white; and, with like relative consequence, white includes all the stimulating powers of colour in painting. It follows that a little white or black is equivalent to much colour, and hence their use as colours requires judgment and caution. By due attention to the synthesis of black, it may be rendered a harmonizing medium to all colours, to all which it lends brilliancy by its sedative effect on the eye, and its powers of contrast: nevertheless, we repeat, it must be introduced with caution when _hue_ is of greater importance than shade.

Even when employed as a shadow, without much judgment in its use, black is apt to appear as local colour rather than as privation of light; and black pigments obtained by charring have a tendency to rise and predominate over other hues, subduing the more delicate tints by their chemical bleaching power upon other colours, and their own disposition to turn brown or dusky. For these reasons deep and transparent colours, which have darkness in their const.i.tution, are better adapted as a rule for producing the true natural and permanent effects of shade. Many pictures of the early masters, and especially of the Roman and Florentine schools, evince the truth of our remarks; and it is to be feared the high reputation of these works has betrayed their admirers into this defective employment of black.

Black substances reflect a small quant.i.ty of white light, which receives the complementary of the colour contiguous to the black. By 'complementary' is meant that colour which is required with another colour to form white light; thus, green is the complementary of red, blue of orange, and yellow of violet, or vice versa; because green and red, blue and orange, and yellow and violet, each make up the full complement of rays necessary to form white light. Briefly digressing, we give the following mode of observing complementary colours:--Place a sheet of white paper on a table opposite to one of two windows admitting diffused daylight[C] into a room; take a piece of coloured gla.s.s and so place it that the coloured light transmitted through it falls over the surface of the paper; then put an opaque object on the paper close to the coloured gla.s.s. The shadow of this object will not appear black or of the colour of the gla.s.s, as might be supposed, but of its complementary colour; thus if the gla.s.s is red, the colour of the shadow will be green, although the whole of the paper surrounding it appears red. Similarly, if the gla.s.s is blue, the shadow will appear orange; if it is green, the shadow will appear red; and so with other colours. It is absolutely essential, however, to the success of this experiment, that the paper be also illuminated with the white light admitted from the other window.

It has been said that black substances reflect a small quant.i.ty of white light, which receives the complementary of the colour contiguous to the black. If this colour is deep, it gives rise to a luminous complementary, such as orange, or yellow, and enfeebles the black; while the other complementaries, such as violet or green, strengthen and purify it. In colours a.s.sociated with black, if green is juxtaposed therewith, its complementary red, added to the black, makes it seem rusty. Those colours which best a.s.sociate with black are orange, yellow, blue, and violet. It would be well to remember that black, being always deeper than the juxtaposed colour, entails contrast of tone, and tends to lower the tone of that colour.

Most of the black pigments in use are obtained by charring, and owe their colour to the carbon they contain. As the objects of vegetal and animal nature may be blackened through every degree of impurity by the action of fire, black substances more or less fitted for pigments abound. The following are the chief native and artificial black pigments, or colours available as such:--

289. BLACK LEAD,

_Plumbago_, or _Graphite_, contains in spite of its name no lead, being simply a species of carbon or charcoal. In most specimens iron is present, varying in quant.i.ty from a mere trace up to five per cent, together with silica and alumina. Sometimes manganese and t.i.tanic acid are likewise found. It is curious that carbon should occur in two distinct and very dissimilar forms--as diamond, and as graphite; one, white, hard, and transparent; the other, black, soft, and opaque: the artist, therefore, who uses a pigment of plumbago, paints with nothing more or less than a black diamond. The best graphite, the finest and most valuable for pencils, is yielded by the mine of Borrowdale, at the west end of Derwent Lake, in c.u.mberland, where it was first wrought during the reign of Elizabeth. A kind of irregular vein traverses the ancient slate-beds of that district, furnis.h.i.+ng the carbon of an iron-grey colour, metallic l.u.s.tre, and soft and greasy to the touch.

Universally employed in the form of crayons, &c. in sketching, designing, and drawing, until of late years it was not acknowledged as a pigment: yet its powers in this respect claim a place for it. As a water-colour, levigated in gum in the usual manner, it may be effectively used with rapidity and freedom in the shading and finis.h.i.+ng of pencil drawings, or as a subst.i.tute therein for Indian ink. Even in oil it may be employed occasionally, as it possesses remarkably the property of covering, forms very pure grey, dries quickly, injures no colour chemically, and endures for ever. These qualities render it the most eligible black for adding to white in minute quant.i.ty to preserve the neutrality of its tint.

Although plumbago has usurped the name of Black Lead, there is another substance more properly ent.i.tled to this appellation, and which may be used in the same way, and with like effects as a pigment. This substance is the sulphide of lead, found native in the beautiful lead ore, or Galena, of Derbys.h.i.+re. An artificial sulphide can be prepared by dry and wet processes, which is subject to gradual oxidation on exposure to the air, and consequent conversion into grey or white. Neither variety can be compared to graphite for permanence, although the native is preferable to the artificial.

Plumbago, or the so-called Black Lead, is often adulterated to an enormous extent with lamp black.

290. BLUE BLACK,

_Charcoal_, _Liege_, or _Vine Black_, is a well-burnt and levigated charcoal prepared from vine twigs, of weaker body than ivory or lamp black, and consequently better suited to the grays and general mixed tints of landscape painting, in which it is not so likely to look black and sooty as the others may do. Of a cool neutral tint, it has, in common with all carbonaceous blacks, a preserving influence on white when duly mixed therewith; which it owes, chemically, to the bleaching power of carbon, and, chromatically, to the neutralizing and contrasting power of black with white. Compounded slightly with blue black, and washed over with zinc white, white lead may be exposed to any ordinary impure atmosphere with comparative impunity. It would be well for art if carbon had a like power upon the colour of oils, but of this it is deficient; and although chlorine destroys their colour temporarily, they re-acquire it at no very distant period.

Alone, blue black is useful as a cool shade for white draperies; and compounded with cobalt, affords a good gray for louring clouds.

291. BRITISH INK

is a compound black, preferred by some artists to Indian ink, on account of its not being liable to wash streaky, as the latter does: at the same time it is not so perfectly fixed on the paper as Indian ink.

292. INDIAN INK,

sometimes called _China_ or _Chinese Ink_, is chiefly brought from China in oblong cakes, of a musky scent, ready prepared for painting in water. Varying considerably in body and colour, the best has a s.h.i.+ning black fracture, is finely compact, and h.o.m.ogeneous when rubbed with water, in which, when largely diluted, it yields no precipitate. Without the least appearance of particles, its dry surface is covered with a pellicle of a metallic appearance. When dry on the paper, it resists the action of water, yet it will give way at once to that action, when it has been used and dried on marble or ivory, a fact which proves that the alummed paper forms a strong combination with the ink; possibly a compound of the latter on an aluminous base, might even be employed in oil. Different accounts are given of the mode of making this ink, the princ.i.p.al substance or colouring matter of which is a smoke black, having all the properties of our lamp black; the variety of its hues and texture seeming wholly to depend on the degree of burning and levigating it receives. From certain Chinese doc.u.ments, we learn that the ink of Nan-king is the most esteemed; and among the many sorts imported into this country, we find those of the best quality are prepared with lamp black of the oil of Sesame; with which are combined camphor, and the juice of a plant named _Houng hoa_ to give it brightness of tone.

According to an a.n.a.lysis by M. Proust, the better kinds contain about two per cent. of camphor. By some, the pigment known as Sepia has been supposed to enter into their composition.

_Liquid Indian Ink_ is a solution for architects, surveyors, &c.

293. IVORY BLACK