MEASUREMENTS ON FINGERNAILS 417 Figure 1. Apparatus for measuring the flexual properties of fingernails

418 .% ,-v v JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 2. Apparatus for cutting fingernail test specimens covered with a rigid plastic backing plate. A movable plunger is brought in contact with the plastic, and a weight is applied to the plunger. The weight forces the sample between the blades resulting in a clean sample, which is parallel to within a few hundred thousands of an inch. All of the specimens used for these experiments were conditioned to 25øC and 65 per cent RH before testing. FLEXURAL TESTING EXPERIMENTS As soon as a sufficient quantity of fingernail samples had been cut and conditioned initial experiments aimed at determining the capabilities of the apparatus were begun. During testing, the samples were subjected to a total deflection of 0.02 in. at a crosshead speed of 0.05 in./min. The testing machine is calibrated to measure forces in