Adding colour: a limited palette, glazes, and leaving white

In the last lesson you translated a subject into three values: light, mid, dark. Now colour joins in, and with it comes watercolour's greatest temptation: wanting too much. This lesson gives you a fixed sequence for applying colour in three manageable passes, without painting the sketch to death.

The three-pass method

Watercolour forgives very little after-the-fact fiddling, which is why a clear sequence helps more than talent. In the first pass you lay in large, light glazes: the sky, sunlit façades, the ground – everything that reads as light overall gets a thin, watery layer of colour, spread generously across wide areas. What counts here is pace, not precision. In the second pass, mid-tones and shadows go in all at once, while the first layer is still damp or has just dried off: window reveals, the shaded sides of buildings, trees in mid-tone. This second layer is the real work of the sketch; this is where form emerges. Only in the third and final pass do you place a few deliberate dark accents: an open door, a window in shadow, the cast shadow under a ledge. These accents are sparing and come last, because dark has the greatest impact when it stays rare.

A palette that's enough

You don't need twenty colours; six are enough for almost any urban subject if you choose them well. Take a warm and a cool version of each primary – yellow, red, blue: a warm yellow such as cadmium yellow alongside a cool lemon yellow, a warm red such as cadmium red alongside a cool carmine, a warm blue such as ultramarine alongside a cool Prussian blue. From these six colours you can mix practically every tone you need for a city scene, and because you always mix from the same small set, your pictures look harmonious automatically. A big, freshly bought tube tempts you to use the colour unmixed, and that's exactly what often makes pictures look restless.

The white you don't paint

The lightest element in your sketch isn't a colour, it's the paper itself. Watercolour has no white from a tube: every highlight, every glint of sun on a windowpane, every bright edge comes about because you simply don't paint there. That demands planning before the first brushstroke: look at your subject and consciously decide which two or three spots are to stay white, before you even pick up water. Usually these are small areas – a reflected highlight, a roof edge, a patch of sun on the street. Paint around these spots rather than scratching them out afterwards. Paper white works all the more strongly the more sparingly you use it; leave too many spots free and each one loses its power.

Shadows: cool and connected

A common mistake is to paint shadows as simply a darker version of the same colour. Shadows are almost always cooler than direct light, because they're lit by the blue light of the sky rather than by the warm sun – so mix a little blue or violet into your shadow tones, even when the shaded surface is actually warm. Just as important: treat all the shadow areas in a scene as one connected shape, not as many separate patches. If a tree's shadow travels across the façade, over the pavement and under a parked car, paint it as one continuous, cool area. That keeps the picture calm, whereas lots of small, individually placed shadow patches make a scene look restless and blotchy.

Mud and hard edges – and how to rescue them

Two mistakes are guaranteed to meet you early on: mud and hard edges. Mud appears when you mix too many colours over or into each other, or stir around too long in a damp area; the colour loses its luminosity and turns into an indeterminate brown-grey. The remedy is restraint: mix the colour fully on the palette before it goes onto the paper, and then leave a stroke alone instead of working it. Hard edges appear when wet paint meets paper that has already dried off; a dark, often cloudy line forms that you never planned. If the spot is still damp, you can carefully brush over it with a clean, only slightly moistened brush and blot the excess colour with kitchen paper. If it has already dried, leave it dry – trying to soften a dry hard edge after the fact almost always makes it worse. Sometimes it's even worth reinterpreting such an edge as a branch, a joint line or a cast shadow instead of fighting it. And if nothing else helps: a thin, even glaze over the whole area, once everything is dry, calms many small blemishes at a stroke.

Exercise

Choose a photo or a subject outside your window with clear light and shadow. From your six-colour palette, pre-mix three or four tones you'll need for the light glaze, and use them in the first pass to lay in the large light areas generously, without paying attention to detail. Let the area dry off, then mix a cool shadow tone and a mid-tone, and in the second pass add form and shadow as one connected whole. Decide beforehand on two spots that are to remain pure paper white, and stick to that strictly. Finally, in the third pass, place at most three or four deliberate accents with a dark mixture. Give yourself 20 minutes in total and watch where mud or a hard edge appears – and whether you can rescue it.

Key points

Light glazes first, mid-tones and shadows in one go, dark accents last and sparingly. Paper white is your lightest colour; plan it before you start painting. Shadows are cool and belong together, not scattered across the picture as separate patches.