Which of the following tool positions is not used in curvature volume?

• A. On-base
• B. Off-base
• C. Overdirected
• D. Underdirected

Answer: (C)

Curvature volume hinges on how each lash fan is anchored and angled so the overall set forms a smooth arc that follows the natural lash line. Placing the base on the natural lash (on-base) gives the strongest root hold and a dense look right at the base, while placing the base away from the root toward the mid-shaft (off-base) creates a lighter lift and helps preserve the curved silhouette without crowding at the root. Adjusting the fan’s direction (underdirected) lets you bias the arc—keeping it within the natural curve rather than flaring outward. Directing the fan too far outward (overdirected) would push lashes away from the intended arc, breaking the curvature and producing a less cohesive look. So overdirected is not used in curvature volume.