FORM and Colour are the twin foundation stones of art. Form must come first, before the application of colour, but construction is the province of the architect. Wall decoration when extensive may be done by the architect, the decorator, or by both working conjointly. Part I of this book gives a thorough consideration of the treatment of walls in all periods, so that nothing pertaining to form remains here for consideration excepting the arrangement and balance of the furniture and other objects to be introduced into the interior and the matters of design and scale. Consideration of these points will naturally come later.

On the other hand, it is impossible for us even to plan our scheme of decoration without reference to the universally interesting subject of colour.

Colour

In this chapter colour will be treated from a simple and practical point of view. It is a subject upon which a vast deal of theory is usually expended, all in itself excellent but usually resulting simply in the obfusca-tion of the general reader. There is perhaps a better way to communicate it.

As everyone knows, the primary colours are yellow, red and blue, and the binary colours (those composed of two) are orange (yellow and red), violet (red and blue) and green (yellow and blue).

Red, yellow and blue are called primary colours because white light in the solar spectrum separates into these three basic colours. As pure light these colours would fuse back into white. In material pigment they do not quite accomplish this but fuse into grey.

Two simple little diagrams will explain the matter of colour. Yellow, red and blue may be called the 11 eternal triangle" of colour - let us so arrange them.

Colour 3

As orange is an equal mixture of normal yellow and red, let us place it midway between its two components, also placing the other two binary colours between the components of each. We then have superimposed a second triangle upon the first.

The dotted lines will show at once the opposing or complementary colours. They are opposing because each of these contains none of the other. Orange is a mixture of yellow and red and contains no blue. Blue and orange are therefore opposing. A glance at the diagram will likewise show the other opposing colours. It is simplicity itself.

There is a curious effect which while, of course, experienced by all artists, has not, to the writers' knowledge, previously been formally pointed out. It is a most important one to be remembered by all who have to handle colour. Let us glance for a moment at our triangle of yellow, red and blue. Yellow and blue, though occupying opposing points of the triangle and thus contrasting, do yet form a harmony of difference, i.e., they are pleasing in combination.

Blue and red also occupy two opposing points of the triangle and while they are less contrasting than blue and yellow are at the same time less pleasing an harmony.

Colour 4

Yellow and red likewise occupy two opposing points of the triangle. Now these, in their pure state, form no harmony, but rather a discord. If we but remember these things, and also that the three colours in the upper left of the diagram (yellow, orange and red) are advancing or aggressive and warm colours and those in the right (green and blue) are retreating or quiet and cool colours, we have already gone far in the understanding of colour for decoration. Violet is neutral. In decorative practice gold also is neutral.

Our useful little diagram shows that normal orange is half way between yellow and red, i.e., it is composed of an equal power of each. It is evident that if more red be added it becomes a reddish orange, and if more yellow it becomes a yellowish orange. It is also plain that if one follows the dotted line from orange across the diagram to its opponent blue and adds blue to orange he will neutralise the orange by the blue he adds until if a sufficient power of blue were added the orange would be totally destroyed and the combination become grey. It is by this adding of a portion of one colour to another, or the adding to them of white or black that tones are made.

The number of hues and tones to be produced by the mixture of colours is necessarily very large. The most prominent are those composed of any one of the six colours on the second diagram with the one next it - thus yellow and orange produce yellow orange. The others in successive order are red-orange, red-violet, blue-violet, blue-green, yellow-green.

In practice the most generally useful colours are the slightly greyed hues of these twelve colours and those known as the Tertiary and Quartenary Colours and are produced as follows:

Tertiary

The mixture of two Binary (sometimes called Secondary) colours - Slate (violet and green), citrine (green and orange), russet (orange and violet).

Quartenary

The Mixture of two Tertiary colours - Sage (citrine and slate), buff (citrine and russet), plum (russet and slate).

As one thinks of such tones as buff, rose, grey, grey-blue, etc., it is plain that such tones are more agreeable and subtle than the strident and hard primary yellow, red and blue.

The strong prismatic primaries and binaries are suitable for accents, about which we shall by-and-by have much to say, but in quantity are not agreeable to cultivated tastes.

With but a few words as to the general characteristics of each colour we shall be ready to proceed to their use in decoration. It should be remembered that these characteristics are those of the pure colours and that in their tones they are modified by the amount of departure from this original.

Yellow

Although sunlight is a white light, yellow gives more of an effect of light than does white itself. If a piece of light yellow paper is placed out of doors on a gloomy day and glanced at through the window it will appear as if the sun were shining upon it. Yellow in its various shades is therefore useful for the lightening of dark rooms.