Undulating outlines can be an expressive mark making element, which can reveal the emotional state of the artist and/or represent the emotional state of the subject being outlined.

Pressure on the brush or drawing implement is increased and decreased throughout each stroke of each outline, creating variations in the stroke's width. The viewer can follow the hand of the artist in time from start to finish of each stroke, sensing perhaps the artist's calm mastery, perhaps the artist's edginess, or perhaps the artist's sloppy irreverence.

The outline is usually of a color and/or value that is distinct from the subjects/shapes. The color(s) chosen for the outlines might have a symbolic meaning, and varied colors can be used around different subjects to allude to a distinct aura that each subject has.

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