IN practice one is often compelled to use to gether colours which do not perfectly harmonize, and it may be as well to note certain simple ways of overcoming the difficulty :
1. Mix a little of each colour with the other Full red and full green, laid side by side are apt to clash badly; but if one takes off the edge of the red with a touch of green, and the edge of the green with a touch of red, the result is a decided improvement.
The operation, a mere question of the palette is as simple as it is obvious, but the resultant tints, though less trying to the eye, are les brilliant than the originals. If the original colours cannot be mixed, the desired result may be produced by working a delicate pattern hatching, or stipple of each over the surface of the other. The resultant in this case will be more brilliant than in the case of the actual mixture of the two colours. The reason of this difference in brilliance is simple, but much too important to be lightly passed over. The mixing of pigments sacrifices light, but the mingling of rays does not. If red paint and green paint be mixed together, the particles are so blended that they seem to obscure one another's brightness, and the light given back from them is dulled; but when lines of red and green are alternated, the red and green rays given back by them are mingled in the air, and the resultant may appear even brighter than the original tints from which it was formed.
This is of great importance in estimating the carrying power of a colour, especially in such a case as that of a poster, in which it is essential that the glitter and brilliance of each tint should be felt as long as the poster remains in sight.
2. Mix a third colour with each of the original colours.
This is simply an adaptation of the ordinary effects of different coloured light upon a landscape, whereby a green tree and a red roof, yellow rick and a blue sky, are made to harmonize. Golden sunlight and grey mist both help to bring together colours not naturally harmonious. The same idea underlies the simple devices of covering the paper with a strong wash before starting a water-colour, or of glazing an oil-painting to pull it together.
As before, the result may be obtained either by actual mixture or by stippling, hatching, or patterning the third colour over each of the two original colours. Yellow-green and scarlet are not exactly harmonious, but they can be greatly helped by working blue over them both. The extent to which the third colour can be used can only be determined by the conditions and by the effect desired.
3. Use a well-defined outline to separate the jarring colours.
Though this is a distinct device it is nearly akin to the last in principle since it introduces a third colour.
The effect will be further altered and made lighter or darker in proportion as the outline is light or dark. Obviously, the broader the outline the more the effect will be altered.
The use of outline in this way deserves careful study. A group of colours which are dull, even though they do not jar, may be made quite brilliant and very attractive by using a broad outline of light or dark to separate them ; or, again, an entire group may be isolated from the ground in the same way. The effect of this is to supplement slow gradations of colour by sharp contrasts of tone, and to turn each patch of colour into a jewel in a setting.
The effect of a coloured outline may be to produce a wonderful glow, provided that the colour is bright enough, and that the enclosed forms are both small and numerous. To study this the same piece of design should be repeated, but with differently coloured outlines, and the effect should be carefully noted. The outline itself will not be visible at a short distance, but the change of colour resulting from its use will be very noticeable.