Any painting, of whatever period, will attain an effect by setting differently coloured areas side-by-side .But a specific colour within a painting can be determined without physical mixing, simply by juxtaposing small areas or taches of those constituent colours which otherwise would be used to mix it subtractively on the palette. Delacroix would paint rapid strokes of purple and green into flesh pink to modulate its appearance from a distance. The Impressionists partially developed this technique, but it was not until the 1880’s that a younger group of artists, led by Seurat, responded to contemporary colour theorists and attempted to place Impressionism on a more consistent footing. Accordingly, they confined their palettes to include only the fully saturated colour-circle colours and white. Thus a green lawn could be rendered with small points of yellow and of blue, a blue sky could be made to shimmer with points of orange, and a brown shadow could be recreated with dots of red, green and a little yellow. In many respects their technique anticipated modern 3-colour printing, although they found that the primaries alone were not, as paints, strong enough to synthesize optically all the colours they needed.
