Common problems with drawing the mouth include heavily outlined lips and teeth, lack of shadow on the gums and teeth, and inadequate modeling of the area around the mouth. Correct lighting of the subject helps to prevent these problems—drawing from flat, flash-lit photographs flattens the subject. If you do a drawing of the skull, or even look at your own teeth, you can see how three-dimensional this part of the face is; it is not at all flat. Take your time and carefully observe the shadows in and around the mouth, as accurately drawing these will solve most of the problem. There is often not much difference in actual tonal value between lip, tooth, and gum, especially when these areas are shaded or highlighted. Use an eraser to soften the edge of the lower lip, and lightly render the upper lip, avoiding outlining. When possible, ask your subject to remove lipstick, as the artificial shine and color emphasizes the lips too much. If drawing lipstick, use a blending stump to create a smooth sheen, reserving white highlights.
Smiling generally involves the whole face, with the corners of the eyes crinkling and the upward movement of the cheeks pushing the lower lids up.
Contemporary style tends to be hard-edged and encourages immediacy of line, so that the mark you place on the paper is left as is. If you want a more traditional look, consider using the blending stump and using soft edges wherever appropriate for a gentle “sfumato” (soft, smoky) effect.
With a closed-mouth smile, there is a sideways tension that pulls the mouth out slightly and compresses the lips, with the cheeks rising slightly. Most people show their teeth when they smile, revealing varying amounts of tooth and gum, with the top lip straight across and the lower lip curved in the classic smile shape. Correctly shading the teeth is the key here—avoid harsh outlines.
Note how the cheeks rise, crinkling the eye area. Some people, especially models and actors, tighten the lower lip downward as they smile, minimizing the distortion of the eye area and revealing less of the upper teeth and gums. With a big, open-mouthed smile—as when laughing or expressing surprise—the point of the chin drops as the muscles of the face pull upward and outward.
