Snap the Chalk Line

What happens here

With the line held taut and pressed against the surface at both ends, use your thumb and forefinger to grasp the chalk line somewhere near its middle. Lift the string directly upwards a few inches from the surface, creating a small amount of slack. Then, quickly release the string, allowing it to snap back down onto the surface. This impact transfers the powdered chalk from the string to the surface, creating a distinct and accurate line. The video demonstrates this snapping action multiple times, yielding single straight lines (e.g., 0:06.000-0:09.000, 0:15.000-0:18.000), a slightly curved line (0:20.000-0:23.000), and a double line by snapping twice slightly offset.

Goal: Produce a visible, accurate line on the surface.