In realistic painting, “lost edges” occur where adjoining shapes are the same color and you can’t see exactly where one ends and another begins. This effect is also called combining shapes, simplification, suggestion, or even achieving a more plastic picture plane. Whatever you call it, painting with lost edges involves recognizing and exploiting the difference between seeing and touching.
Babies are born with an exquisite sense of touch, but their eyesight takes over a year to fully develop. Children draw their mother’s face as three dots and a line because that’s how it felt in their earliest memory of her, regardless of how it looks to them now. Touch continues to inform and even dominate sight into adulthood. That’s why it’s so hard to learn how to draw realistically—what you know from your early experience through the sense of touch confuses and overpowers what you actually see in the present.
For day-to-day survival, the marriage of sight and touch in the mind of the observer is essential. You look at a tree and your visual cortex says, “I can’t see the tree trunk in the middle of the tree.” Your tactile cortex replies, “Don’t worry, I can image running our hand up the trunk behind the leaves—I’m sure the trunk continues all the way up.” What you have touched in the past and what you can imagine touching fill in the gaps in your current visual field, allowing you to climb or trim or pick fruit off the tree with confidence.
Painting the tree is another story. You are likely to paint a complete scaffolding of trunk and branches first, then hang leaves from it, because that’s how your sense of touch tells you a tree is constructed. This knowledge distorts and overpowers how this tree actually looks from this vantage point, in this light. Beginning painters have their tactile cortex too fully engaged, so they show all the edges, outline all the shapes, paint each object separately like a kid filling in a coloring book.
Learning to paint well means learning to see without the distortions of touch. Actually look at the tree. Notice how many edges and shapes are not actually visible. Sunlight and shade hide edges. There are places where the trunk and the leaves merge in the same brown/green/gray tones.
Experienced painters try to turn off their tactile cortex so they can experience their subjects as purely visual phenomena. Then they recreate in paint what they actually see, leaving out what they imagine touching. Sometimes they even create more lost edges than are present in their subjects, by adding or deleting objects, changing the light source, inventing shadows, or moving things around in the composition.
Lost edges allow your painting’s viewers to use their own tactile imaginations to fill in details. This is more fun for them than relying on you to spell everything out.