Quantifying Hair Motion.

A commercially-available instrument, previously intended to visualize and quantify hair shape and volume, has been modified to measure hair motion. Specifically, a transversal motor now induces a side-to-side oscillating tress stimulus, while a video camera records the outcome. Image analysis software allows for quantifying the amount of motion (i.e. the amplitude), the shape and volume of the hair during motion, and the homogeneity of the hair (i.e. bulk -vs- flyaways). Each of these parameters has considerable dependence on the frequency of oscillation and so evaluations are carried out by systematically varying this parameter. Preliminary validation experiments are documented which involved methodical variation of parameters that were presumed to be of importance. These included the size and shape of hair tresses, various hair treatments, and environmental conditions. As a result of the sizable amount of data that results, graphical depictions provide the best means of representation. For example, amplitude -vs- frequency plots describe the extent of hair motion as a function of energy supplied to the system. Visually noticeable decreases in tress motion were observed after applying small quantities of silicone oil to the hair. This occurrence reduced the measured amplitude of tress motion, while also moving the maximum amplitude to high frequency. Accordingly, it is supposed that improved motion is attained by inducing a higher amplitude at a given frequency, and/or by attaining comparable amplitude under the application of a lower frequency.