Olive In Dark Green; Russet And Citrine In Dark Orange The

: ON COLOURS AND PIGMENTS GENERALLY.

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.









TTITLE ON THE DURABILITY AND EVANESCENCE OF PIGMENTS.



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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