_SALTER'S EDITION._
FIELD'S CHROMATOGRAPHY;
OR,
TREATISE ON COLOURS AND PIGMENTS
AS USED BY ARTISTS.
_AN ENTIRELY NEW AND PRACTICAL EDITION_;
REVISED, REWRITTEN, AND BROUGHT DOWN TO THE PRESENT TIME.
BY
THOMAS W. SALTER, F.C.S.
Ars probat artificem.
LONDON:
WINSOR AND NEWTON, 38, RATHBONE PLACE,
Manufacturing Artists' Colourmen by Special Appointment
to Her Majesty, and Their Royal Highnesses the Prince and
Princess of Wales.
[The Right of Translation is reserved.]
CONTENTS.
PART I.
ON COLOURS AND COLOURING.
Chapter. Page.
I.--On Colouring 3
II.--On the Relations and Harmonies of Colours 13
PART II.
ON COLOURS AND PIGMENTS GENERALLY.
III.--On Classes of Colours 27
IV.--On the Durability and Fugacity of Pigments 31
V.--On the General Qualities of Pigments 46
PART III.
ON COLOURS AND PIGMENTS INDIVIDUALLY.
VI.--On Colours and Pigments individually 57
VII.--On the Neutral, White 62
VIII.--On the Primary, Yellow 81
IX.--On the Primary, Red 127
X.--On the Primary, Blue 183
XI.--On the Secondary, Orange 239
XII.--On the Secondary, Green 263
XIII.--On the Secondary, Purple 294
XIV.--On the Tertiary, Citrine 310
XV.--On the Tertiary, Russet 320
XVI.--On the Tertiary, Olive 325
XVII.--On the Semi-Neutral, Brown 334
XVIII.--On the Semi-Neutral, Marrone 362
XIX.--On the Semi-Neutral, Gray 372
XX.--On the Neutral, Grey 381
XXI.--On the Neutral, Black 387
Addendum 414
Index 417
NOTICE.
Among the works consulted in this Edition are the following, from most
of which extracts have been taken:
Bancroft's Philosophy of Colours.
Brande's Manual of Chemistry.
Chemical News.
Chevreul on Colour.
Fownes' Manual of Chemistry.
Gmelin's Handbook of Chemistry.
Handbooks on Art.
Liebig and Kopp's Annual Report of the Progress of Chemistry.
Mérimée's Painting in Oil.
Muspratt's Dictionary of Chemistry.
Normandy's Commercial Handbook of Chemical Analysis.
O'Neill's Chemistry of Calico Printing.
Quarterly Journal of the Chemical Society.
Ruskin's Elements of Drawing.
Watts' Dictionary of Chemistry.
PART I.
* * * * *
ON COLOURS AND COLOURING.
CHROMATOGRAPHY;
OR,
A TREATISE ON COLOURS AND PIGMENTS.
* * * * *
CHAPTER I.
ON COLOURING.
How early, and to what extent, colouring may have attained the rank of
science among the ancients, are questions not easily set at rest; but
that some progress had been made, even at a very remote period, is
proved by the magnificent tombs of the Egyptian kings at Thebes, where
the walls of the royal mausoleum are described as being covered with
paintings so fresh and perfect, as to require neither restoration nor
improvement. So far from this, indeed, that with all care in copying, it
was difficult to equal the brilliancy of the originals, which, as far as
colours went, threw all others in the background. And yet, in spite of
the scale having comprised pure vermilion, ochres, and indigo, it was
not gaudy, owing to the judicious balance of the colours, and the
artful management of the black. Nor was there an ornament throughout the
dresses, wherein the red, yellow, and blue, were not so employed as to
produce a delicious harmony.
Moreover, it is stated that in one painting eighty feet high and
proportionably broad, which was divided into two ranges of gigantic
figures, these were glowing with most exquisite colours, suited to the
drapery and naked parts; and in which the azure, yellow, green, &c.,
were as well preserved as though they had been laid on yesterday. Again,
an apartment was discovered among the stupendous ruins at Carnac, on the
site of ancient Thebes, one hundred paces wide and sixty deep,
completely crowded with pillars, which, together with the ceiling, roof,
and walls, were decorated with figures in basso-relievo, and
hieroglyphics--all marvellously beautiful and finely painted, and as
fresh, splendid and glorious, after so many ages, as if they had just
been finished.
In various accounts these colourings of the Egyptians are described in
the warmest terms of admiration. The most charming are undoubtedly those
on the tombs and temples: others of less merit have been found on the
cases and cloths of mummies, and on papyrus rolls; but it is to the
patterns on the walls and ceilings of their houses that they seem to
have been most partial, and paid the most attention. The ordinary
colours employed by them were red, yellow, green, and blue. Of the last
there were two tints; black also was common. For white, the finely
prepared stone-coloured ground was deemed sufficient. These colours were
occasionally modified by mixture with chalk; but were always, or nearly
always, applied singly, in an unmixed state. With regard to their
composition, chemical analysis has shown several of the _blues_ to be
oxide of copper with a small proportion of iron; none containing cobalt.
There is little doubt, however, that the most brilliant specimens--those
which retain all their original force and beauty in the temples of Upper
Egypt after an exposure of three thousand years, consist of
ultramarine--the celebrated Armenian blue, possibly, of the ancients.
The _reds_ seem for the most part to be composed of oxide of iron mixed
with lime, and were probably limited to iron earths and ochres, with a
native cinnabar or vermilion. The _yellows_ are said to have been, in
many cases, vegetable colours; but it is likely earths and ochres were
their chief source. The _greens_ consist of yellow mixed with copper
blue. The bluish-green which sometimes appears on Egyptian antiquities,
is merely a faded blue. The _blacks_ are both of vegetable and mineral
origin, having been obtained from a variety of substances in a variety
of ways.
But, as shown by Layard in his discoveries at Nineveh, a knowledge of
colouring was not confined to the Egyptians; it was likewise possessed
by the Assyrians. The painted ornaments of the latter are stated to have
been remarkably elegant; and although the colours were limited to blue,
red, white, yellow, and black, yet they were arranged with so much taste
and skill, and the contrasts were so judiciously preserved, that the
combinations were in general agreeable to the eye. The pale
yellowish-white ground on which the designs were painted, resembled the
tint on the walls of Egyptian monuments, and a strong well-defined black
outline was found to be as peculiar a feature in Assyrian as in Egyptian
painting, black frequently combining with white alone, or alternating
with other colours. As far as they have been analysed, the pigments
employed were mineral, the brightest being a blue derived from copper.
No traces of vegetable colours have been found; it is presumed that they
existed, but being subject to more rapid decay than the mineral
pigments, they have disappeared. That all the colours, indeed, employed
by the ancients were not permanent, was proved by the fact of certain
blues and reds, brilliant and vivid when the earth was removed from
them, fading rapidly when exposed to the air.
From Philocles, the Egyptian, and Gyges, a Lydian, both of whom,
according to Pliny, acquired the knowledge of the art of painting in
Egypt, the Greeks obtained the knowledge of their _Ars Chromatica_,
which they are said to have carried by gradual advances during several
centuries, from the monochromatic of their earlier painters, to the
perfection of colouring under Zeuxis and Apelles, 450 to 350 B.C.
Unfortunately, not long after, or about 300 B.C., art rapidly
deteriorated; the invasion of the Romans commenced; and the principles
of light, shade, and colours in painting as understood by the Greeks,
together with their valuable treatises on the subject were lost. The
early Roman and Florentine painters, so eminent in other respects, were
almost destitute of those principles, and of truly refined feeling for
the effects of colouring.
The partial restoration of this branch seems to have been coeval with
the earliest practice of painting in oil. The glory of it belongs to the
Venetians, to whom the art of painting passed with the last remains of
the Greek schools after the capture of Constantinople at the beginning
of the thirteenth century. Giovanni Bellini laid the foundation of
colouring, and Titian carried it to its highest practical perfection.
From the Venetian it extended to the Lombard, Flemish, and Spanish
schools. In the practice of these, however, there was perhaps as much of
instinct as principle, colouring still remaining to be established in
its perfection as a science.
According to the true, natural, and philosophical classification of
painting, there are but three principal classes or schools; viz.: the
gross and _material_ which is content with mere nature, and to which
belong the Dutch and Flemish schools; the _sensible_, which aims at
refined and select nature, and accords with the Venetian school; and the
_intellectual_, which aspires to the ideal in beauty, grandeur, and
sublimity, and corresponds with the Greek, Roman, and Florentine
schools. Modern art as founded upon the _intellectual_ school of the
ancient Greeks, became grand, scientific, and severe in the practice of
Michael Angelo, and Leonardo da Vinci; graceful, beautiful and
expressive in Raphael, Correggio, Dominichino, and Guido; and, aiming at
_sensible_ perfection, it attained harmony of colouring and effect in
the works of Titian and Tintoret; but it sunk into grossness and
sensuality while perfecting itself _materially_ among the Flemish and
Dutch.
In the practice of the individual in painting, as well as in all
revolutions of pictorial art, in ancient Greece as in modern Italy,
colouring in its perfection has been the last attainment of excellence
in every school. It has been justly observed, indeed, that for near
three hundred years, since painting was revived, we could hardly reckon
six painters that had been good colourists, among the thousands who had
laboured to become such. But there is reason to hope that as Zeuxis
succeeded and excelled Polygnotus, and Titian Raphael, the artists of
Britain will transcend all preceding schools in the chromatic department
of painting. It is even probable that they may surpass them in all other
branches, and in every mode and application of the art, as they have
already more particularly done in an original and unrivalled use of
water-colours.
Happily, too, there has arisen among us a school of colouring that
confirms this expectation, strengthened as it is, by the suitableness of
our climate to perfect vision. For in it we have that mean degree of
light which is best adapted to the distinguishing of colours, a
boundless diversity of hue in nature relieved by those fine effects of
light and shade which are denied to more vertical suns, besides those
beauties of complexion and feature in our females peculiar to England;
respects in which at least our country is not unfavourable to art.
Even now it is urged by some to the _disparagement_ of the British
school, that it excels in colouring; as if this were incompatible with
any other excellence, or as if nature, the great prototype of art, ever
dispensed with it. The graphic branches of painting, owe everything to
colour, which, if it does not constitute a picture, is its flesh and
blood. Without it, the finest performances remain lifeless skeletons,
and yield no pleasure. Painting is the art of representing visible
things by light, shade, form, and colour; but of these, colour--and
colour alone--is the immediate object which attracts the eye. Colouring
is, therefore, the first requisite--the one thing imparting warmth and
life--the chief quality engaging attention; in short, the best
introduction to a picture, and that which continues to give it value so
long as it is regarded. It is a power, too, which is with the most
difficulty retained, being the first to leave the artist himself, and
the first to quit a school on its decline. Graphic art without
colouring, is as food without flavour; and it was the deficiency of
colouring in the great works of the Roman and Florentine schools that
caused Sir Joshua Reynolds to confess a certain want of attraction in
them. To relish and estimate truly their greatness, required, he said, a
forced and often-repeated attention, and "it was only those persons
incapable of appreciating such divine performances, who made pretensions
to instantaneous raptures on first beholding them." Gainsborough also,
with a candour similar to that of Reynolds, upon viewing the cartoons at
Hampton Court, acknowledged that their beauty was of a class he could
neither appreciate nor enjoy.
Colouring, then, is a necessity; but there is in it a vicious extreme;
that in which it is rendered so principal as, by want of subordination,
to overlay the subject. There is also a negative excellence which
consists in not always employing pleasing tints, but of sometimes taking
advantage of the effects to be derived from impure hues, as Poussin did
in his "Deluge." In this work, neither black nor white, blue, red, nor
yellow appears; the whole mass being, with little variation, of a sombre
grey, the true resemblance of a dark and humid atmosphere, by which
every object is rendered indistinct and almost colourless. This absence
of colour, however, is a merit, and not a fault. Vandyke employed such
means with admirable effect in the background of a Crucifixion, and in
his Pieta; and the Phaëton of Giulio Romano is celebrated for a
suffusion of smothered red, which powerfully excites the idea of a world
on fire.
Of the rank and value of this department of painting, there will be, as
there has been, difference of judgment and opinion, as there is variety
in the powers of the eye and understanding. But take from Rubens,
Rembrandt, Titian, and other distinguished masters, the estimation of
their colouring, and we fear all that is left to them would hardly
preserve their names from oblivion. Art cannot, indeed, attain its
appropriate end, that of pleasing, without excellence in colouring. It
is colour which the true artist most loves, and it is colouring in all
its complex and high relations, that he ever seeks to attain. Looking
above, and around, and beneath him, with the intelligent eye of the
colourist, he finds a boundless source of never-ceasing enjoyment. With
harmonies and accordances lost to the untutored gaze, colour meets him
in every stone he treads on--in the mineral, vegetable, and animal
creation--in the heavens, sea, and earth. For him, in truth, colour is
as equally diffused as light, spreading itself over the entire face of
nature, and clothing the whole world with beauty.
CHAPTER II.
ON THE RELATIONS AND HARMONY OF COLOUR.
Assured as we must be of the importance of colouring as a branch of art,
colours in all their bearings become interesting to the artist, and on
their use and arrangement his reputation as a colourist must depend.
Colour, remarks Ruskin, is wholly _relative_; each hue throughout a work
is altered by every touch added in other places. Thus, to place white
beside a colour is to heighten its tone; to set black beside a colour is
to weaken its tone; while to put grey beside a colour, is to render it
more brilliant. If a dark colour be placed near a different, but lighter
colour, the tone of the first is heightened, while that of the second is
lowered. An important consequence of this principle is, that the first
effect may neutralize the second, or even destroy it altogether. What
was cold before, becomes warm when a colder colour is set near it, and
what was in harmony before, becomes discordant as other colours are put
beside it. For example, to place a light blue beside a yellow, tinges
it orange, and consequently heightens its tone. Again, there are some
blues so dark relatively to the yellow that they weaken it, and not only
hide the orange tint, but even cause sensitive eyes to feel that the
yellow is rather green than orange--a very natural result when it is
considered that the paler the yellow becomes, the more it tends to
appear green.
We learn from these relations of colours, why dapplings of two or more
produce effects in painting so much more clear and brilliant than
uniform tints obtained by compounding the same colours: and why
hatchings, or a touch of their contrasts, thrown as it were by accident
upon local tints, have the same effect. We see, too, why colours mixed
deteriorate each other, which they do more--in many cases--by
imperfectly neutralizing or subduing each other chromatically, than by
any chemical action. Finally, we are impressed with the necessity, not
only of using colours pure, but of using pure colours; although pure
colouring and brilliancy differ as much from crudeness and harshness, as
tone and harmony from murkiness and monotony.
The powers of colours in contrasting each other agree with their
correlative powers of light and shade, and are to be distinguished from
their powers individually on the eye, which are those of light alone.
Thus, although orange and blue are equal powers with respect to each
other, as regards the eye they are totally different and opposed. Orange
is a luminous colour, and has a powerfully irritating effect, while blue
is a shadowy colour, possessing a soothing quality--and it is the same,
in various degrees, with other colours.
There are yet further modes of contrast or antagonism in colouring,
which claim the attention and engage the skill of the colourist. Of the
contrast of _hues_, upon which depend the brilliancy, force, and harmony
of colouring, we have just spoken; but there is, secondly, the contrast
of _shades_. To this belong all the powers of chiaroscuro, by which term
the painter denotes the harmonious effects of light and shade; and
though they form the simplest part of colouring, yet they cannot be
separated from it--light and shade, the chiaroscuro, being a distinct
and important branch of painting. A third mode of contrast in colouring
is that of _warmth_ and _coolness_, upon which depend the toning and
general effect of a picture. Fourthly, there is the contrast of _colour_
and _neutrality_, the chromatic and achromatic, or hue and shade. By the
right management of this, local colours acquire value, gradation,
keeping, and connection: whence come breadth, aërial perspective, and
the due distribution of greys and shadows in a picture.
This principle of contrast applies even to _individual colours_, and
conduces greatly to good colouring. It may be carried with advantage
into the variety of hue and tint in the same colour, not only as regards
light and shade, but likewise with respect to warmth and coolness, as
well as to colour and neutrality. Hence the judicious landscape-painter
knows how to avail himself of warmth and coolness in the juxtaposition
of his greens, in addition to their lightness and darkness, or
brilliancy and brokenness, in producing the most beautiful and varied
effects; effects which spring in other cases from a like management of
blue, white, &c. These powers of a colour upon itself are highly
important to the artist, and lead to that gratification from fine
colouring, which a good eye ever enjoys.
In landscape we see nature employing broken colours in harmonious
consonance and variety, while, equally true to picturesque relations,
she uses also broken forms and figures, in conjoint harmony with
colours; occasionally throwing into the composition a regular form, or a
primary colour, for the sake of animation and contrast. And if we
inspect her works more closely, we shall find that they have no uniform
tints. Whether in the animal, vegetable or mineral creation--flesh or
foliage, earth or sky, flower or stone--however uniform the colour may
appear at a distance, it will, when examined nearly, be found to
consist of a variety of hues and shades, compounded with harmony and
intelligence.
It is for this reason that no two colours are ever found discordant in
nature, however much so they may be in art. Blue and green have been
termed discordant, and in painting they may undoubtedly be made so. Yet
those are two colours which nature seems to intend never to be
separated, and never to be felt, either of them, in its full beauty,
without the other--a blue sky through green leaves, or a blue wave with
green lights through it, being precisely the loveliest things, next to
clouds at sunrise, in this coloured world of ours. A good eye for colour
will soon discover how constantly nature puts green and purple together,
purple and scarlet, green and blue, yellow and neutral grey, and the
like; and how she strikes these colour-concords for general tones,
before working into them with innumerable subordinate ones.
Upon the more intimate union, or the blending and gradience of contrasts
from one to another mutually, depend some of the most fascinating
effects of colouring. The practical principle employed in producing them
is important, and consists in the blending and gradating by _mixture_,
while we avoid the _compounding_ of contrasting colours. That is, the
colours must be kept distinct in the act of blending them, or otherwise
they will run into dusky neutrality and defile each other. This is the
case in blending and gradating from green to red, or from hue to
hue--from blue to orange, or to and from coldness and warmth--from
yellow to purple, or to and from advancing and retiring colours. It is
the same in light and shade, or white and black, which _mix_ with
clearness. Now, there are only two ways in which this distinctness in
union of contrasts can be effected in practice: the one is by hatching
or breaking them together in mixture, without compounding them
uniformly; and the other is by glazing, in which the colours unite and
penetrate mutually, without monotonous composition.
The former process may be said to be the carrying out of the principle
of separate colours to the utmost possible refinement, by using atoms of
colour in juxtaposition, instead of in large spaces. And it is to be
noted, in filling up minute interstices of this kind, that if the colour
with which they are filled be wanted to show brightly, a rather positive
point of it had better be put, with a little white left beside or round
it in the interstice. This plan is preferable to laying a pale tint of
the colour over the whole interstice. Yellow or orange, for instance,
will hardly show, if pale, in small spaces; but they show brightly in
free touches, however small, with white beside them. The latter mode is
founded on the fact, that if a dark colour be laid first, and a little
blue or white body-colour struck lightly over it, a more beautiful gray
will be obtained than by mixing the colour and the blue or white.
Similarly, if over a solid and perfectly dry touch of vermilion there be
quickly washed a little very wet carmine, a much more brilliant red will
be produced than by mixing the two colours.
Transparency and opacity constitute another contrast of colouring, the
former of which belongs to shade and blackness, the latter to light and
whiteness. Even contrast has its contrast, for _gradations_ or
_intermedia_ are opposed to contrasts or _extremes_; and, upon the right
management of contrasts and gradations depend the harmony and melody,
the tone, effect, and general expression of a picture. Thus, painting is
an affair of judicious contrasting so far as regards colour, if even it
be not such altogether.
Colour, it has already been observed, is wholly _relative_. In
contrasting, therefore, any colour, if we wish it to have light or
brilliancy, we cast its opposite into the shade; if we would have it
warm, we cool its antagonist; and if transparent, we oppose it by an
opaque contrary, and _vice versâ_: indeed, in practice, all these must
be in some measure combined.
Such are some of the powers of contrast in colouring alone, and such is
the diversity of art upon which skill in colouring depends. It must not
be forgotten, however, that contrasts or extremes, whether of light and
shade, or of colours, become violent and offensive when they are not
reconciled by the interposition of their media, or intermediates, which
partake of both extremes of the contrasts. Thus blue and orange in
contrast become reconciled, softened in effect, and harmonized, when a
broken colour composed of the two intervenes. The same may be said of
other colours, shades, and contrasts.
Seeing that the management and mastery of colours are to a great extent
dependent on the same principles as light and shade, it might become a
point of good discipline, after acquiring the use of black and white in
the chiaroscuro, to paint designs in contrast; that is, with two
contrasting colours only, in conjunction with black and white--for
example, with blue and orange, before attempting the whole. Indeed,
black can be dispensed with in these cases, because it may be
compounded, since the neutral grey and third colours always arise from
the compounding of contrasting colours. In this way, even flesh may be
painted--for instance, with red and green alone, as Gainsborough is said
at one period to have done.
Some artists have produced pictures in the above hot and cold colours
only; which, although captivating to the eye, and true in theory with
respect to colour, light and shade, are generally false in practice with
regard to nature, which rarely employs such extreme accordances.
Colouring like this, therefore, is more beautiful than true. It is as
though a painter were to execute a landscape in the full light of day,
as he saw it looking through a prism, so that every object glowed with
rainbow hues. Such a picture would present a beautiful fairy scene, and
be true as regards colours, but as respects nature, it would be false.
Colour, and what in painting is called transparency, belong chiefly to
shade. It has been a common error to ascribe those properties to light
only, and hence many have employed a uniform shade tint, regarding
shadows as simply darkness, blackness, or the mere absence of light;
when, in truth, shadows are infinitely varied by colour, and always so
by the colours of the lights which produce them. But while we incline
attention toward the relation of colour to shade, both light and shade
being strictly co-essential to colour, a vicious extreme must be
avoided. For although, as transparent, colour inclines to shade, and, as
opaque, it partakes of light; yet the general tendency of colour is to
transparency and shade, all colour being a departure from light. Hence
it becomes a maxim, which he who aspires to good colouring must never
lose sight of, that _the colour of shadow is always transparent, and
only that of extreme light objects opaque_. It follows, that white is to
be kept as much as possible out of shadow, and black, for the same
reason, out of colour. In their stead, whenever it is necessary to
cover, opaque tints may be employed, glazed over with transparent
colours. Such practice would also be more favourable to durability of
the tones of pictures, than the shades and tints produced with black and
white. The hues and shadows of nature are in no ordinary case either
black or white, which, except as local colours, are always poor and
frigid. The perfection of colouring is to combine harmony with
brilliancy, unity with variety, and freshness with force, without
violating the laws of nature.
With regard to the _perspective of colours_, or the manner in which they
affect the eye, according to position and distance, it is a branch of
aërial perspective or the perspective of light and shade. This is
distinguished from linear perspective, or the perspective of drawing, as
drawing is from colouring; and they have progressed alike in the art.
The most ancient painters seem to have known little of either; and
linear perspective was established as science before the aërial, as
drawing and composition preceded colouring.
The perspective of colours depends upon their powers to reflect the
elements of light, powers which are by no means uniform. Accordingly,
blue is lost in the distance before red, and yellow is seen at a point
at which red would disappear; yet blue preserves its hue better than
yellow, because colours are cooled in the distance. In this respect,
the compound colours partake of the powers of their components, in
obedience to a general rule, by which local colours closely connected
with black are first lost in the distance, and those nearly related to
white disappear last. The same may be said of local light and shade, the
latter of which is totally lost at great distances; and it is for this
reason the shadowed side of the moon is not generally seen. These powers
of colours are, however, varied by mist, air, altitude, and mixture,
which produce evanescence; and by contrast, which preserves the force of
colours by distinguishing them. Colours do not decline in force so much
by height as by horizontal distance, because the upper atmosphere is
less dense and clouded with vapour: and hence it is that mountains of
great elevation appear much nearer than they really are. From all these
circumstances, it is evident that a simple scumbling or uniform
degradation of local colours will not effect a true perspective--for
this will be the aërial of light and shade only--but such a
subordination of hues and tints, as the various powers of colours
require, and as is always observable in nature.
In furnishing or _setting the palette_ philosophically and upon
principle, it is necessary to supply it with pure blue, red, and yellow;
to oppose to these an orange, of a hue that will neutralise the
blue--green, of a hue that will neutralise the red--and purple, of a hue
that will neutralise the yellow; and so on to black and white, which
will neutralise each other. As in nature, the general colour of the sky
is blue, and the colour of light is always opposite to that of the sky
and shade, so the white which is to represent light should be tinged
with the orange of the palette sufficiently to neutralise the
predominant coldness of black. Pure neutral white may thus be reserved
as a "local" colour, which is a technical term for the _natural_ colour
of an object, unvaried by distance, reflection, or anything interfering
with distinct vision; although, properly speaking, local colours are
subject to all the relations and effects of the places they occupy in a
composition--whether of light, shade, reflection, or distance.
From what we have said, it will be seen that the relations and harmony
of colours form a complex subject, requiring constant and careful study;
one, indeed, into which he who would become a colourist must enter heart
and soul. For as colouring is the beginning and end of a painter's
craft, so colour in all its aspects must be the chief lesson of his
life. And this lesson can only be learnt, by ever watching with a loving
eye those wondrous colourings of nature, in which there is nothing
inharmonious or out of place.
PART II.
* * * * *
ON COLOURS AND PIGMENTS GENERALLY.
CHAPTER III.
ON CLASSES OF COLOURS.
By mixing his _colours with white_, the artist obtains his _tints_. By
mixing _colours with colours_, he produces compound colours, or _hues_.
And by mixing _colours or tints with black_, he gets _shades_. It is a
common error to confound these distinctions.
The above classification of colours enables us to understand the
simplicity of relation which exists among an infinity of tints, hues,
and shades of colour. Also, it is calculated to give precision to
language respecting colours, the nomenclature of which has too often
been vague and uncertain.
There are five classes of colours, viz.:--the _Neutral_, the _Primary_,
the _Secondary_, the _Tertiary_, and the _Semi-neutral_.
_Neutral Colours_ are three only, _white_, _black_, and grey. According
to the laws of Optics, the two first comprise all other colours
synthetically, and afford them all by analysis. These are sometimes
called "extreme" colours, grey being their intermediate.
_Primary Colours_ are three only, _yellow_, _red_, and _blue_. They are
such as yield others by being compounded, but are not themselves capable
of being produced by composition of other colours. By way of
distinction, they are occasionally designated "entire" colours.
_Secondary Colours_, are three only, _orange_, _green_, and _purple_.
Each of these is composed of, or can be resolved into, two primaries.
Thus, orange is composed of red and yellow; green, of yellow and blue;
and purple, of blue and red.
_Tertiary Colours_ are three only, _citrine_, _russet_, and _olive_.
Each of these is composed of, or can be resolved into, either two
secondary colours, or the three primaries. Thus, citrine consists of
green and orange, or of a predominant yellow with blue and red; russet
is compounded of orange and purple, or of a predominant red with blue
and yellow; and olive is composed of purple and green, or of a
predominant blue with yellow and red.
The last three genera of colours comprehend in an orderly gradation all
those which are _positive_ or definite; and the three colours of each
genus, united or compounded in such subordination that neither of them
predominates to the eye, constitute the _negative_ or neutral colours,
of which _black_ and _white_ have been stated to be the opposed
extremes, and _greys_ their intermediates. Thus black and white are
constituted of, and comprise latently, the principles of all colours,
and accompany them in their depth and brilliancy as shade and light.
_Semi-neutral Colours_ belong to a class of which _brown_, _marrone_,
and _gray_ may be considered types. They are so called, because they
comprehend all the combinations of the primary, secondary, and tertiary
colours, with the neutral _black_. Of the various combinations of black,
those in which yellow, orange, or citrine predominates, have obtained
the name of brown, &c. A second class in which the compounds of black
are of a predominant red, purple, or russet hue, comprises marrone,
chocolate, &c. And a third class, in which the combinations of black
have a predominating hue of blue, green, or olive, includes gray, slate,
&c.
While treating of the classes of colours, it may not be out of place to
note here the difference between gray as spelt with an _a_, and grey as
spelt with an _e_, the two names being occasionally confounded. _Gray_
is semi-neutral, and denotes a class of cool cinereous colours, faint of
hue; whence we have blue grays, olive grays, green grays, purple grays,
and grays of all hues in which blue predominates; but no yellow or red
grays, the predominance of such hues carrying the compounds into the
classes of brown and marrone, of which gray is the natural opposite.
_Grey_ is neutral, and is composed of or can be resolved into black and
white alone, from a mixture of which two colours it springs in an
infinite series.
It must be observed that each colour may comprehend an indefinite series
of _shades_ between the extremes of light and dark, as each compound
colour also may comprise a similar series of _hues_ between the extremes
of the colours composing it. And as the relations of colours have been
deduced regularly, from white or light to black or shade; so the same
may be done, inversely, from black to white. On this plan the
tertiaries, olive, russet, and citrine, take the place of the primaries,
blue, red, and yellow; while the secondaries still retain their
intermediate station and relation to both.
Thus, _russet and olive_ compose or unite in _dark purple_; _citrine and
olive_ in _dark green_; _russet and citrine_ in _dark orange_. The
tertiaries have, therefore, the same order of relation to black that the
primaries have to white; and we have black primaries, secondaries, and
tertiaries, inversely, as we have white primaries, secondaries, and
tertiaries, directly. In other words, we have light and dark colours in
all classes.
CHAPTER IV.
ON THE DURABILITY AND EVANESCENCE OF PIGMENTS.
Pigments may be defined as colours in a solid or insoluble state,
prepared for the artists' use. Hitherto, we have treated of colours in
the abstract sense, as appealing to the eye only: we have now to
consider them as material bodies.
As colour itself is relative, so is durability of colour relative. For
the reason that all material substances are changeable and in perpetual
action and reaction, no pigment is so permanent as that nothing will
alter its colour. On the other hand, none is so fugitive as not to last
under some favouring circumstances. Time, of long or short continuance,
has often the effect of fire, more or less intense. Indeed, it is some
sort of criterion of the stability and changes of colour in pigments,
that time and fire are apt to produce similar effects thereon. Thus, if
fire deepen, or cool, or warm a colour, so may time; if it vary its
hues, so may time; if it destroy a colour altogether, so may time
ultimately. The power of time, however, varies extremely with regard to
the period in which it produces those effects, that are instantly
accomplished by fire.
That there is no absolute but only relative durability of colour may be
proved from the most celebrated pigments. For instance, the colour of
native ultramarine, which will endure a hundred centuries under ordinary
circumstances, may be at once destroyed by a drop of lemon juice; and
the generally fugitive and changeable carmine of cochineal will, when
secluded from light and air, continue fifty years or more; while fire or
time, which merely deepen the former colour, will completely dissipate
the latter. Again, there have been works of art in which the white of
lead has retained its freshness for ages in a pure atmosphere, but has
been changed to blackness after a few days' or even hours' exposure to
foul air. These and other peculiarities of colours will be noticed, when
we come to speak of pigments individually; not for the purpose of
destroying the artist's confidence, but as a caution, and a guide to the
availing himself of their powers properly.
It is, therefore, the lasting under the usual conditions of painting,
and the common circumstances to which works of art are exposed, that
entitles a colour to the character of permanency; and it is the
not-so-enduring which attaches to it rightly the opposite character of
evanescence: while a pigment may obtain a false repute for either, by
accidental preservation or destruction under unusually favourable or
fatal circumstances.
Many have imagined that colours vitrified by intense heat are
consequently durable when levigated for painting in oil or water. Had
this been the case, the artist need not have looked farther for the
furnishing of his palette than to a supply of well-burnt and levigated
enamel pigments. But though such colours for the most part stand well
when fluxed on glass, or in the glazing of enamel, they are nearly,
without exception, subject to the most serious changes when ground to
the degree of fineness necessary to their application as pigments, and
become liable to all the chemical changes and affinities of the
substances which compose them. These remarks even apply in a measure to
native products, such as coloured earths and metallic ores.
Others have not unreasonably supposed that when pigments are locked up
in varnishes and oils, they are safe from all possibility of change. The
assumption would be more warranted if we had an impenetrable
varnish--and even that would not resist the action of light, however
well it might exclude the influence of air and moisture. But, in fact,
varnishes and oils themselves yield to changes of temperature, to the
action of a humid atmosphere, and to other influences: their protection
of colour from change is therefore far from perfect.
Want of attention to the unceasing mutability of all chemical
substances, as well as to their reciprocal actions, has occasioned those
changes of colour to be ascribed to fugitiveness of the pigment, which
belong to the affinities of other substances with which it has been
improperly mixed and applied. It is thus that the best pigments have
suffered in reputation under the injudicious processes of the painter;
although, owing to a desultory practice, the effects and results have
not been uniform. If a colour be not extremely permanent, dilution will
render it in some measure more weak and fugitive; and this occurs in
several ways--by a too free use of the vehicle; by complex mixture in
the formation of tints; by distribution, in glazing or lackering, of
colours upon the lights downward, or scumbling colours upon the shades
upward; or by a mixed mode very common among the Venetian painters, in
which opaque pigments are combined, as umber and lake.
The fugitive colours do less injury in the shadows than in the lights of
a picture, because they are employed pure, and in greater body in
shadows, and are therefore less liable to decay by the action of light,
and by mixture. Through partially fading, moreover, they balance any
tendency to darken, to which the dead colouring of earthy and metallic
pigments is disposed.
The foregoing circumstances, added to the variableness of pigments by
nature, preparation, and sophistication, have often rendered their
effects equivocal, and their powers questionable. These considerations
enforce the expediency of using colours as pure and free from
unnecessary mixture as possible; for simplicity of composition and
management is equally a maxim of good mechanism, good chemistry, and
good colouring. Accordingly, in respect to the latter, Sir Joshua
Reynolds remarks, "Two colours mixed together will not preserve the
brightness of either of them single, nor will three be as bright as two:
of this observation, simple as it is, an artist who wishes to colour
bright will know the value."
There prevail, notwithstanding, two principles of practice on the
palette, opposed to each other--the one, simple; the other, multiple.
The first is that of having as few pigments as possible; and consists,
when carried to the extreme, in employing the three primary colours
only. The second is that of having a number of pigments; and consists,
also when carried to the extreme, of employing as many, if possible, as
there are hues and shades of colour.
On the former plan, every tint requires to be compounded; on the latter,
one pigment supplies the place of two or more. Now, the more pigments
are mixed, the more they are deteriorated in colour, attenuated, and
chemically set at variance. Original pigments, that is, such as are not
made up of two or more colours, are purer in hue and generally more
durable than those compounded. Hence pure intermediate tints in single,
permanent, original pigments, are to be preferred to pigments
compounded, often to the dilution and injury of their colours. Cadmium
Orange, for instance, which is _naturally_ an orange pigment and not
composed of red and yellow, is superior to many mixtures of those
colours in a chemical sense, and to all such mixtures in an artistic
sense. At the same time, it is quite possible for the artist to multiply
his pigments unnecessarily. Colours are sometimes brought out under new
names which have no claim to be regarded as new colours, being, indeed,
mere mixtures. Compound pigments like these may most frequently be
dispensed with, in favour of hues and tints composed extemporaneously of
original colours upon the palette.
It may be inferred from the foregoing that, between the modes of
employing as few pigments as possible, and of having as many as there
are hues and shades of colour, a middle course is the best. But,
whatever the practice adopted, permanent _original_ pigments should be
used as often as the case will admit; it being borne in mind, that a
pigment may be compound, although its colour may be primary. As a rule,
the less colours are mixed, the purer, brighter, and more lasting they
will be found.
To the practice of producing tints and hues by _grinding_ pigments
together, instead of _blending_ them on the palette, may be attributed
some of the peculiarities of the tints and textures of the Flemish
school; they being, perhaps, results of intimate combination from
grinding, and consequently of a more powerful chemical action among the
ingredients compounded. This method has, in a great measure, fallen into
disuse, and undoubtedly it conduced to foulness when the colours of the
pigments ground were not pure and true, and did not assimilate well in
mixture chemically.
The superiority of Rubens and the Flemings, and of Titian and the
Venetian school, in colouring and effect, is due in a considerable
degree to their sketching their designs in colours experimentally with a
full palette. This practice, as derived from Reynolds, is common with
the best masters of our own school, who, in executing their works,
resort also to nature, with an improved knowledge of colours and
colouring. Such attention to colouring and effect, from the first study
and ground of a picture to the finishing, contributes a beauty to the
painting no superinduced colouring can accomplish.
The durability of colour in substances is to a great extent dependent
upon the condition in which they exist chemically. If pigments, for
example, be in a state which chemists have termed _pro_toxide, they are
liable to absorb oxygen on exposure to light, air, or moisture, and
becoming what is called _per_oxidized, may, by consequence, change or
fade. In like manner, lakes and carmines thrown down upon a base, may
owe some of their fugacity to the oxidation of that base, as well as to
the natural infirmity of their colouring matter. On the other hand,
pigments and bases are subject to _de_oxidation, or to a loss of oxygen,
in which case the colour is apt to deepen. Pigments generally are more
affected by oxidation and fading in a water vehicle, and by deoxidation
and darkening in one of oil.
A principal test of permanency in pigments is the impunity with which
they bear exposure to light and air, an artistic proof of their
stability the mere chemist is apt to neglect. Provided the colour remain
unaffected by sulphuretted hydrogen, &c., he seldom hesitates to
pronounce it safe. But a pigment may be fast in one sense and fugitive
in another, believed in by the laboratory, and found wanting by the
studio. It has happened before now that the same colour has been dubbed
durable and the reverse, by the man of science and the man of art. The
former, we take it, looks upon a pigment as a coloured substance of a
certain composition, possessing maybe an acid and a base, either, or
neither, or both of which, gases and other reagents may injure or
destroy. The latter views a colour chiefly as part and parcel of his
picture--that picture which _may_ meet with foul exhalations, but _must_
be exposed to light and air. And he too often thinks as little of the
effects of an impure atmosphere or injudicious admixture, as the chemist
considers the action of air and light.
With the exception of madder, those colours mostly affected by _light
and air_ are of organic origin, such as gallstone, Indian yellow, and
the yellow dye-wood lakes; the red and purple lakes of cochineal;
indigo; and sap green. To these may be added the semi-organic Prussian
blue; and the inorganic yellows and orange of arsenic.
The pigments liable to injury from _sulphuretted hydrogen_, &c., are
notably those obtained from lead and copper; and that treacherous
compound of iodine and mercury, known as pure scarlet.
Many colours are apt to change from the action of white _lead_ and other
lead pigments, &c., principally those which are altered by light and
air.
Many, too, cannot safely come into contact with iron, or ferruginous
pigments; especially the yellows of arsenic, the lakes of cochineal, and
the blues and greens of copper. With these an iron palette knife is best
avoided, one of ivory or horn being used instead. The latter, indeed, is
preferable in all cases, several pigments being slightly affected by
iron, cadmium yellow among the number.
Numerous colours are likewise injured by _lime_ and _fire_, and cannot
therefore be employed in fresco, or enamel painting.
Of substances which may act deleteriously on colours, there remain the
_vehicles and varnishes_ with which they are mixed. Many of these have
been blamed, and often with justice, for their injurious effects on
pigments. The reputation of the most permanent colour may be ruined, if
the vehicle, &c., employed with it be untrustworthy. The presence of
lead, for instance, in such materials renders them liable to be
blackened by foul air, and by consequence the pigments used therewith.
Time produces in many cases a mellow and harmonious change in pictures,
but occasionally alterations altogether unfavourable. To ensure the
former and prevent the latter, the attention of the artist in the course
of his colouring should be to the employment of such pigments and
colours as are prone to adapt themselves, in changing, to the intended
key of his colouring, and the right effect of his picture. Thus, if he
design a cool effect, ultramarine has a tendency through time to
predominate and aid the natural key of blue. He will, therefore,
compromise the permanence of this effect, if in such case he employ a
declining or changeable blue, or if he introduce such reds and yellows
as have a tendency to warmth or foxiness, by which the colouring of
many pictures has been destroyed. In a glowing or warm key, the case is
in some measure reversed--not wholly so, for it is observable that those
pictures have best preserved their colouring and harmony in which the
blue has been most lasting, by the pigment counteracting the change of
colour in the vehicle, and that suffusion of dusky yellow which time is
wont to bestow upon pictures even of the best complexion.
Unless introduced and guaranteed by houses of acknowledged reputation,
newly discovered pigments are to be used with caution. Good colours have
ever been prized with so true an estimation of their value, that to
produce such, after so many ages of research is no ordinary
accomplishment. But too many resplendent pigments, fruits of the
fecundity of modern chemistry, have been found deficient. The yellow and
orange chromates of lead, for instance, withstanding as they do the
action of the sunbeam, become by time, foul air, and the influence of
other pigments, inferior to the ochres. So the dazzling scarlet of
iodine and mercury must yield the palm of excellence to the more sober
vermilion, being a chameleon colour, subject to the most sudden and
opposite changes. And the blues of cobalt, as always tending to
greenness and obscurity, cannot rank beside ultramarine.
We are far from asserting, however, that all modern pigments are
inferior, or that pigments should be looked upon with suspicion because
they are modern. Several most valuable colours have lately claimed
attention, notably the permanent transparent yellow called _Aureolin_.
Seeing that, until its introduction, a yellow combining transparency
with a perfect stability was unknown to the palette, the importance of
such an addition, so long wanted and wished for, cannot be overrated.
Equal in beauty and durability with the preceding, but possessing
greater richness and depth, and of a semi-opacity, another yellow of the
highest order merits regard, _Orient Yellow_, distinguished for its
lustrous golden hue, resembling a bright Indian yellow. Dazzling in
brilliancy, and absolute in permanency. _Cadmium Red_ next attracts
notice. This new aspirant for artistic fame is a most vivid
orange-scarlet, the latter colour predominating, of intense fire, but
with no approach to rankness or harshness, yielding delicate pale
washes, and blending happily with white in the formation of flesh tints.
With it may be coupled _Cadmium Orange_, a colour equally brilliant and
stable, and equally without rankness or harshness, but of a true orange
hue, admirably adapted for sunsets and the like. Last of all the fresh
pigments of whose thorough durability there is _no_ doubt, comes the
splendid _Viridian_, a green nothing but fire will change, and no
mixture of blue and yellow will afford. Clear, bright, and transparent
as the emerald, it rivals velvet in its soft gorgeous richness. With
this and Aureolin a series of beautiful foliage tints may be formed,
sparkling with sunshine, as it were.
Other colours there are which have been brought forward within the last
few years, not possessing the absolute permanency of the five foregoing,
but equal, or superior, to many formerly used. It were folly, therefore,
and a silly conservatism on the part of the artist to limit himself to
such pigments only as were employed by his forefathers, especially as
their merits were often more than doubtful. New colours, it is true,
have to be _learnt_, for each pigment has its own peculiar habitudes,
chemical, physical, artistic; but if they be good and durable, no amount
of time and study spent upon them is thrown away. To think less of the
quality of one's materials than of the effects which can be produced
with them is mistaken policy; and to be content with that quality when
better can be had, shows no real love of art, but rather indolence and
apathy.
Perhaps one reason why freshly introduced pigments have not as fair a
chance as they are entitled to, is due to the fashion which prevails of
exclaiming against the fugacity of modern colours. If their detractors
would confine themselves to certain colours, there could be no denial;
but to assert, as is often done, that the cause of modern pictures not
standing is owing to modern pigments generally, is unjust. It is not
the materials which should be blamed, but those who use them. The fact
is, that the artist's knowledge has not increased in proportion to the
greater variety of colours at his command. In the early periods of art,
when the palette was chiefly confined to native pigments, the painter
could not very well go wrong. Now-a-days but too many, wanting the skill
of the old masters, seek to make amends for it by brilliancy of
colouring: with imperfect knowledge of their materials the result is
obvious. The palette, we admit, wants weeding; not only of the bad new
colours, but of the bad old colours. This, however, must be a work of
time, and depend, not upon the colourman--for where there is a demand
there will be a supply--but upon the artists themselves. To this end an
increased acquaintance with the properties of pigments is required,
whereby they may be able to choose the fast from the fugitive. It may be
fairly assumed that the painter will be assisted in his task by the
progress of chemical science, which will doubtless add from time to time
to the list of stable pigments. We have heard it remarked that there are
too many colours already--to which we reply, there are not too many good
colours, and scarcely can be. The more crowded the palette is with
reliable pigments, the more likely are the worthless to be pushed from
their places. In our opinion, there is ample room for fresh colours,
provided they be durable; and we have as little sympathy with the
stereotyped cry of there being too many, as with the fashionable
unbelief in modern pigments. Certainly, the artist who seeks for
permanence among the whites, reds, or blues, will not be troubled with a
superfluity. Certainly, too, colours are as good as ever they were, and
better--better made, better ground, better prepared for use. But, fast
and fugitive, pigments are more numerous, and for that reason need more
careful selection.
CHAPTER V.
ON THE GENERAL QUALITIES OF PIGMENTS.
The general attributes of a perfect pigment are beauty of colour,
comprehending pureness and richness, brilliancy and intensity, delicacy
and depth,--truth of hue--transparency or opacity, well-working,
crispness, setting up, or keeping its place, and desiccation, or drying
well. To all of these must be superadded _durability_ when used, a
quality to which the health and vitality of a picture belong, and one so
essential that all other properties put together without it are of no
esteem with the artist who merits reputation. We have, therefore, given
it a previous distinct consideration.
It must be observed that no pigment possesses all the foregoing
qualifications in perfection, some being naturally at variance or
opposed; nor is there any, perhaps, that cannot boast excellence in one
or more of them.
_Beauty_ commonly comprises in the same pigment delicacy, purity, and
brilliancy; or depth, richness, and intensity. Delicacy and depth in
the beauty of colours are at variance in the production of all pigments,
so that perfect success in producing the one is attended with more or
less of failure in the other, and when they are united--as they
occasionally are--it is with some sacrifice of both. Hence the judicious
artist purveys for his palette at least two pigments of each colour, one
eminent for delicate beauty, the other for richness and depth.
_Truth of hue_ is a relative quality in all colours, except the extreme
primaries, in the relations of which, blue, being of nearest affinity to
black or shade, has properly but one other relation, in which it
inclines to red and becomes purple-blue: it is, therefore, faulty or
false, when, tending to yellow, it becomes of a green hue. But red,
which is of equal affinity to light and shade, has two relations, by one
of which it verges upon blue and becomes a purple-red or crimson; and by
the other it leans to yellow, and becomes an orange-red or scarlet,
neither of which is individually false or discordant. Yet yellow, which
is of nearest affinity to white or light, has strictly but one true
relation, by which it inclines to red, and becomes a warm or orange
yellow, for by uniting with blue it becomes a defective green-yellow.
The best example of true yellow in a pigment, tending neither to red nor
blue, is furnished by _Aureolin_, alluded to in the last chapter. The
secondary and tertiary colours, having all duplex relations, may
incline without default to either of their relatives.
_Transparency_ is an essential property of all glazing pigments, and
adds greatly to the value of dark or shading colours; indeed it is the
prime quality upon which depth and darkness depend, as whiteness, or
light, does upon opacity or reflecting power. _Opacity_ is, therefore,
the antagonist of transparency, and qualifies pigments to cover in
dead-colouring, or solid painting, as well as to combine with
transparent colours in forming tints; and hence it is that
semi-transparent pigments are suited in a mean degree both for dead
colouring and for finishing. As excellencies, therefore, transparency
and opacity are relative only--the first being as indispensable to shade
in all its gradations, as the latter is to light. With regard to
transparent and opaque colours generally, it is worthy of attention in
the practice of the oil-painter, that the best effects of the former are
produced when they are used with a resinous varnish; as opaque pigments
are best employed in oil, and the two become united with best effect in
a mixture of these vehicles. The natural and artificial powers, or depth
and brilliancy, of every colour lie within the extremes of black and
white; hence it follows that the most powerful effects of transparent
colours are obtained by glazing them over black and white. As, however,
few transparent pigments have sufficient body, or tinging power for
this, it is often necessary to glaze them over tints, or deep opaque
colours of the required hues. There is a charm in transparent colours
which frequently leads to an undue use thereof in glazing; but glazing,
scumbling, and their combined process must be employed with discretion,
according to the objects and effects of a picture.
_Working well_ is a quality which depends principally upon fineness of
texture, and what is called _body_ in colours; yet every pigment has its
peculiarities in respect to working both in water and oil, and these
must become matter of every artist's special experience. Some of the
best pigments are most difficult of management, while some ineligible
colours are rich in body and free in working. Accidental circumstances,
however, may influence all pigments in these respects, according to the
painter's particular mode of operation, and his vehicle; upon the
affinities of colours with which depend their general faculties of
working--such as keeping their place, crispness or setting up, and
drying well. These latter, with other properties and accidents of
pigments, will be particularly considered in treating of their
individual characters; but it may be remarked that crispness or setting
up, as well as keeping their place and form in which they are applied,
are contrary to the nature of many pigments, and depend in painting with
them upon a gelatinous mixture of their vehicle. For example, mastic
and other resinous varnishes impart this texture to oils which have been
rendered drying by the acetate, or sugar of lead:--simple water, also
albumen, and animal jelly made of glue and isinglass, give the same
quality to oils and colours; and bees-wax has a similar effect in pure
oils. Whitelac varnish, and other spirit varnishes, rubbed into the
colours on the palette likewise enable them to keep their place very
effectually in most instances. This is important, because glazing cannot
be performed except with a vehicle which keeps its place, or with
pigments which lend this property to the vehicle, as some lakes and
transparent colours do.
_Fineness of texture_ is produced by extreme grinding and levigation.
Pigments ground in water in the state of a thick paste, are miscible in
oil and dry therein firmly; and in case of utility or necessity, any
water-colour in cake, being rubbed off thick in water may be diffused in
oil, the gum acting as a medium of union between the two. Thus, pigments
which cannot otherwise be employed in oil, or varnish, may be forced
into the service and add to the resources of the oil-painter, care being
taken to use the palette-knife, if of steel, with caution.
_Desiccation or drying._ The well-known additions of the acetate, or
sugar of lead, litharge, and sulphate of zinc, either mechanically
ground, or in solution, for light colours; and japanner's gold size, or
oils boiled upon litharge, for lakes; or, in some cases, manganese and
verdigris for dark colours, are resorted to when the pigments or
vehicles are not sufficiently good dryers alone. It would be well if
lead and copper could be banished from the list of siccatives
altogether: assuredly, no artist with any regard for the permanent
texture of his work should employ them except in extreme cases, and in
the smallest possible quantity. The best of pigments may be ruined by
their injudicious use, and obtain a character for fugacity which they in
no way deserve. It requires attention that an excess of dryer renders
oil saponaceous, is inimical to drying, and is otherwise injurious. Some
colours dry badly from not being sufficiently edulcorated or washed.
Sulphate of zinc, as a siccative, is less powerful than acetate of lead,
but is far preferable in a chemical sense. It is supposed erroneously to
set the colours running; which is not positively the case, though it
will not retain those disposed to move, because it wants the property
the acetate of lead possesses, of gelatinizing the mixture of oil and
varnish. These two dryers should not be employed together, since they
counteract and decompose each other, forming two new substances--acetate
of zinc, which is a bad siccative, and sulphate of lead, which is
insoluble and opaque. The inexperienced ought here to be guarded against
the highly improper practice of some artists, who strew their pictures
while wet with acetate of lead, or use that substance in some other
mode, without grinding or solution; which, though it may promote present
drying, will ultimately effloresce on the surface of the work, throw off
the colour in sandy spots, and expose the paintings to peculiar risk
from the damaging influence of impure air.
It is not always that ill drying is to be attributed to the pigments or
vehicles, the states of the weather and atmosphere have great influence
thereon. The direct rays of the sun are powerfully active in rendering
oils and colours siccative, and were probably resorted to before dryers
were--not always wisely--added to oils, particularly in the warm climate
of Italy. The ground may also advance or retard drying, because some
pigments united by mixing or glazing, become either more or less
siccative by their conjunction. Many other accidental circumstances may
likewise affect drying; and among these none is to be more guarded
against by the artist than the presence of soap and alkali, too often
left in the washing of his brushes, and which, besides other bad
results, decompose and are decomposed by acetate of lead and most
siccatives. In such cases desiccation is retarded, streaks and patches
are formed on the painting, and the odium of ill drying falls upon some
unlucky pigment. To free brushes from this disadvantage, they should be
cleansed with linseed oil and turpentine. Dryers should be added to
colours only at the time of using them, because they exercise their
drying property while chemically combining with the oils employed,
during which the latter become thick or fatten. Too much of the
siccative will, as before noticed, often retard drying.
The various affinities of pigments occasion each to have its more or
less appropriate dryer; and it would be a matter of useful experience if
the habits of every colour in this respect were ascertained. It is
probable that siccatives of less power generally than the compounds of
lead and copper might come into use in particular cases, such as the
oxides of manganese, to which umber and the Cappagh browns owe their
drying quality.
To other good attributes of pigments, it would be well if we could in
all cases add the property of being _innoxious_. As this, however,
cannot be, and colours are by no means to be sacrificed on that account,
cleanliness and avoiding the habit of putting the brush unnecessarily to
the mouth, so common in water-painting, are sufficient guards against
any possibly pernicious effects from the use of any pigment. No colour
which is not imbibed by the stomach will in the slightest degree injure
the health of the artist.
PART III.
* * * * *
ON COLOURS AND PIGMENTS INDIVIDUALLY.