Tutored Life Drawing Blog Week 10: Tonal edges (Patreon)

A tonal edge describes the boundary between two areas of contrasting tonal value. This might be a sharp change, with an obvious edge, or a gradual transition between the two tones. Tonal edges are an essential, but often overlooked, part of observational drawing, and expressing these different changes in tone carefully allows for more naturalistic drawings.

Todays blog examines how to differentiate edges and how to translate your observations of edges into a drawing.

Main image: Saphire

Types of Tonal Edge

Dividing tonal edges into different types helps simplify the infinite variety of edges. Edges can be immediate in their transition between tones, or so fuzzy no clear boundary can be discerned. All that is needed is two neighbouring areas of different tonal value.

Breaking edges into these types is an artificial way of distinguishing them.

There are a few different approaches to categorising edges. Different artists may use slightly different words, talking about 'sharp' rather than 'hard' edges, but the meaning is the same. I like to separate tonal edges into:

• Hard edges: these are immediate transitions from one tone to another.
• Firm edges: edges with a slight 'fuzziness' to them.
• Soft edges: edges that are noticeably fuzzy.
• Gradient: an area where the change in tone is gradual.

A drawing can include all of these, or only some. When drawing organic subjects, such as the human figure, most edges will likely be firm and soft, with a few gradients and hard edges around the outline of the figure. You will see more hard edges on man-made objects, or under strong lighting conditions. The figure tends to have rounded forms, and body hair (even if it is a light fuzz) often soften hard edges into firm ones.

This photo shows a variety of different edges, with some labelled examples.

Lost Edges

In some parts of a subject you might encounter lost edges. A lost edge occurs when a previously clear edge of any degree of hardness or softness - usually one that represents a physical contour - seems to disappear into an area of constant tone, although the edge has become invisible (or 'lost') we know that it still exists. Our brains want to fill in that lost edge and in a line drawing you might still draw the contour-edge with a line, despite having visually lost it; in a visually representational tonal drawing it is a good habit to draw it as you see it and allow it to remain lost. 

The hard edges either side give way to an area in the middle where we imagine an edge to be, even though it has become 'lost' in constant tonal values. 

Lost edges in a tonal drawing of a sphere

It can be hard to see lost edges in reference images because good photographic lighting is often set up to create contrasts in the figure which minimise lost edges. Here is an example of an almost-lost-edge.

Observation and Edges

A common challenge in tonal drawing is creating the right kind of edge between different areas. It is easy to draw an excessive  of hard edges, leading to a harsh, linear feel to a drawing, or not committing to enough firm edges, resulting a drawing too misty to have clear structure.

It helps to pay attention to how observed tonal changes are read as edges. Different edges can be the result of many factors, such as light and shadow patterns, surface changes and contrast, or more indirect techniques such as atmospheric tone (see week 4).

The edges of the form shadows on the arm are firmer around the wrist, where the form has a sharper 'turn' compared to the more rounded forms of the muscles.  The cast shadow edge is harder near the arm it is cast from, and gets softer with distance.

Round forms tend to have a soft shadow edges, due to the gradual change in the direction the surface faces. Tighter turns in form creates a firmer shadow edge. At its most extreme, geometric forms like cubes – a common element of man-made objects – have hard shadow edges for their corners. In the figure, bony areas tend to have harder shadow edges than areas with more muscle or fat, which tend to be rounder.

Cast shadows can also vary in their edges, due to the distance between the shadow and what is casting it; shadows soften with distance from what is casting them. Cast shadow edges also imitate whatever is casting them, so if something soft or fluffy casts a shadow, the shadow edge will be soft too.

Both are affected by the light source; intense light sources create crisper shadows, whilst more diffuse, or 'fuzzy' light sources create softer shadows.

These different facial features rely on varied edges. Look for the different kinds of edges – hard, firm, soft and gradients – in each example.

Surface can affect edges as well. Facial features are a particularly common subject where surface forms are important. Ever tried to draw lips, and ended up with a result that seems harsh and unrealistic? Lips are a particular challenge of edges, because there is such a gentle transition from the edge of the lips to the surrounding skin. In the above drawings, the outer edges of the lips merge into the surrounding skin, whilst the central area, which turns form more suddenly, has a firmer edge.

The edges in the shadowy areas of this drawing become harder to discern, as there is less tonal contrast. Well lit areas show greater clarity – one way to think of this is more light equals more visual information.

It becomes harder for the eye to differentiate edges as contrast diminishes, especially in low light. If you look into a shadowy corner of your surroundings, it will likely be difficult to make out the boundaries between tonal shapes. One way of handling this is to make these edges softer, more faithfully imitating visual perception.

These are just a few reasons observed edges may vary. Manipulating edges for other reasons – such as composition or exaggeration – is also possible.

Comparing Edges in Artwork

 Georges Seurat - Embroidery; The Artist's Mother (Source: New York MET)

The structure of this drawing relies on edges and subtle tonal shifts. There are no hard edges, and most tonal edges are very soft orgradients, with only a few firmer ones surrounding the patch of light under the sitter's chin. However, the features and hands are still easy to discern, despite being often considered areas requiring tight detail.

A common trap when drawing is becoming over-reliant on details and hard edges, however they are not necessarily that important. Varied edges are a natural result of accurately observing a subject, as it is unlikely the same kind of edge will persist throughout. However, edges are also something that can be manipulated suit personal taste.

Henri Fantin-Latour - Self Portrait (Source: New York MET)

This is another example of work where soft, loose edges predominate, this time in paint. Hard and firm edges are starting to emerge, with the white edge of the collar, and lights on the nose and ear. However, the shadowy eye socket shows only the most subtle indication of the eye.

The softness of the hair is portrayed with loose brushstrokes as well. Edges are a valuable tool in describing textures; this loose rendering helps indicate the soft transition of hair to skin, and the diffuseness of the strands of hair.

Honoré Daumier - A Man Reading in a Garden (Source: New York MET)

This sketch by Honoré Daumier shows the use of varied edges for a figure in a setting. This is done by combining tonal transitions and lines, where the lines are used to add a bit more clarity.

Note how the shadow shapes are unified by gradients, merging the figure into the surrounding pools of shadow by his foot. Around the perimeter of the figure there is a variety of contrasts and edges. The top right side shows a harder dark edge on the light background, alternating to softer contrasts with the dark of the hat on the shadowy foliage, and trouser leg against the lawn. The left side of the figure shows firmer edges under the light, up to the soft boundary of that anchoring leg.

Key Points to remember about Tone:

• Edges are the boundaries between contrasting areas of tone or colour.
• Edges can be broadly separated into different types: sharp, firm, soft, and lost.
• Varying edges can help create more interesting drawing results, and portray tonal values in a more naturalistic way.

Over to You – Edges in Drawing

Recommended Materials: Graphite, charcoal, or conté.

Further Reading: 02-Contour, 08-Tonal Value, 09-Tonal Shapes 

Exercise 1: Edge Drawing Study

This exercise can be done with any subject matter, though it works well with still life subjects or scenery, such as landscapes and interiors. Pick a pressure sensitive medium, such as charcoal or soft graphite pencils. The approach is similar to the continuous line drawing exercise from the first lesson, Introduction to Life Drawing.

By following the contours of the subject, make a continuous line, pressing harder for the sharper edges, and lighter for soft and lost edges. Don't worry too much about getting accurate contours.

This drawing, done in charcoal pencil, shows darker lines where the edges get sharper. Towards the centre of the plant, there were more shadows, making the edges hard to discern.

Exercise 2:  Copy a Portrait Painting

Good edges are a key ingredient to painting, and it is possible to learn a lot from them that translates to drawing. Often painters will manipulate edges significantly.

For this exercise, select a portrait painting – it is fine to try this with other subject matter, but portraiture offers a contained subject. Using a medium that is quite malleable, such as willow charcoal, or wet, like ink or watercolour, create a copy, focusing on the variety of edges in the painting.

Try working at a smaller scale to avoid getting bogged down with details. Instead, look for the broad changes in edges, and think about how they are used. Is the artist changing them to manipulate focus, or is the edge quality consistent throughout? Doing multiple small studies from different artists is a great way to approach this.

Study from Rembrandt - 'Portrait of Gerard de Lairesse' (Approximately A5.)

Exercise 3: Soft to Hard Edge Tonal Drawing

In this exercise, it is again fine to draw any subject. It is best to use something soft and malleable, such as charcoal, a soft graphite (4B or higher) or conté.

Start by laying in the subject in loose, soft tonal shapes. These should be blurry and fuzzy – avoid committing to any edges or drawing any underlying construction lines.

After drawing the subject out in loose tone, start to refine the shapes. Do this by adding darker tone to create firmer edges and erasing unwanted tone. Work until the drawing feels resolved – this is largely up to your own taste. It might be finding a likeness, a sense of balance between edges, or enough detail to feel complete. Consider the earlier examples – a loose, soft drawing may fulfil the original intention.

If drawing too many hard edges is a common issue for you, this is an especially useful exercise.

This portrait was done entirely in willow charcoal. I defined the shapes by blending the charcoal with a make-up pad and erasing out light shapes.

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Further links

>> Watch the Week 10: Tonal Edges main lesson HERE (Student & Life Tiers)  
>> Watch the Week 10: Tonal Edges demo HERE (Student & Life Tiers)

Find links to the whole Tutored Life Drawing Course HERE