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.

TTITLE 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

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