Of the Expression and Relief of Line and Form by Colour—Effect of same Colour upon different Grounds—Radiation of Colour—White Outline to clear Colours—Quality of Tints relieved upon other Tints—Complementaries—Harmony—The Colour Sense—Colour Proportions—Importance of Pure Tints—Tones and Planes—The Tone of Time—Pattern and Picture—A Pattern not necessarily a Picture, but a Picture in principle a Pattern—Chiaroscuro—Examples of Pattern-work and Picture-work—Picture-patterns and Pattern-pictures.
Perhaps the most striking means of the expression of relief of line and form, certainly the most attractive, is by colour. By colour we obtain the most complete and beautiful means of expression in art.
Relief of Line and Form by Colour
Our earliest ideas of form are probably derived through the different colours of objects around us, by which they are thrown into relief upon the background, or against other objects; and, as I mentioned in the first chapter, we reach outline by observing the edges of different masses relieved as dark or light upon light or dark grounds, so now, in my last, we come again to the consideration of the definition of line and form by colour, and their relief and expression upon different planes or fields of colour.
There is first the colour of the object itself—the local colour—and then the colour of the ground upon which it is relieved, both of which in their action and reaction upon each other will greatly affect the value of the local colour and the degree of relief of the form upon it.
One of the best and simplest ways to ascertain the real value of a colour and its effect upon different grounds or fields is to take a flower—say a red poppy, and place it against a white paper ground, blocking in the local colour as relieved upon white, as near as may be to its full strength, with a brush, and defining the form as we go along. Then try the same flower upon grounds of different tints—green, blue, yellow—and it will be at once perceived what a different value and expression the same form in the same colour has upon different tinted grounds. A scarlet poppy would appear clearest and darkest upon white; it would show a tendency upon a blue ground to blend or blur at its edges, and also on yellow and green to a less extent.
It is this tendency to lose the edges of forms owing to the radiation of colours, and to mingle with the colour of the background, which makes a strong outline so constantly a necessity in decorative work. One may use a black on a white, a brown, or a gold outline (as in cloisonné), the nature of the outline being generally determined by the nature of the work. In stained glass the outline must be black, and this black is of the greatest value in enhancing by opposition the brilliance of the colours of the glass it incloses, stopping out the light around it as it does in solid lead when placed in the window.