Values Before Colour: The 3-Tone Sketch

Many beginners stand in front of a subject agonising over the exact colour of a tiled roof or a façade. Yet what usually decides whether a picture works is something else entirely: the value, meaning the brightness of an area, independent of its hue. This lesson shows you how to work with just three tones and why that will improve your sketching straight away.

Why values matter more than colour

Take a photo of a street scene and convert it to black and white in your mind: you can still clearly make out the buildings, the people, the depth of the space. If, on the other hand, you colour that same image completely wrong but keep the correct differences in brightness, it still reads convincingly. This shows that our eye reads an image first through brightness contrast and only afterwards through colour. A façade in warm rather than cool grey is barely noticeable, but a façade that is exactly as light as the sky behind it makes the whole picture look flat. If you deal with the values first, a large part of the picture's impact is already in place before a single hue has been decided.

The three tones: light, mid, dark

To get started, it's enough to assign every area of your subject to one of three categories: light, mid or dark. Deliberately do without finer gradations, those will come by themselves later. The sky and sunlit surfaces usually belong to light, most façades and roads to mid, shadow areas, window openings and passageways to dark. The skill lies not in hitting every tone perfectly, but in keeping the three categories clearly apart: a mid tone must not suddenly look as light as your light, otherwise the structure of the picture blurs.

The squint test

To recognise the values of a subject, a simple trick helps: narrow your eyes almost shut so that you're looking through just a thin slit. Details disappear, colours fade, but the large light-and-dark zones stand out clearly. With this squint test you immediately see which area reads as light overall and which as dark, without being distracted by colour or detail. Use it right in front of the subject before you start painting, and by all means in between as well, to check whether your sketch still follows the same distribution of values as the real scene.

The value thumbnail in three minutes

Before you start the actual sketch, a value thumbnail is worth the effort: a thumbnail-sized preliminary sketch in which, in just three minutes, you divide the subject into the three values light, mid and dark using a single grey tone or a pencil. It's not about shapes or details, only about assigning rough areas to the right values: where does the paper stay white, where does a mid grey go, where do you place the darkest spots? This thumbnail often shows you whether a subject works as a picture before you've invested any time in the large sketch at all. If the thumbnail looks washed out because too many areas sit at the mid value, it's worth switching subject or deliberately strengthening the darkest value.

Exercise

Take a grey watercolour or mix a neutral grey from your palette. Look out of the window or find a subject outdoors with clear light and shadow, for example a row of houses with a sunny side and a shadow side. First make a value thumbnail in pencil, matchbox-sized, three minutes, only three tones. Then transfer the distribution of values to a larger sketch, using only your one grey tone and no other colour. Allow yourself 15 to 20 minutes in total and use the squint test in between to check whether your three tones are still clearly distinct.

Key points

The eye reads brightness contrast first and colour only afterwards, which is why values come before the choice of colour. The squint test shows you in seconds which areas are really light, mid or dark. A three-minute value thumbnail saves you time because it weeds out subjects that don't work before you start the large sketch.