A new instrumental method which allows us to measure hair raspiness in a wet condition has been developed. The remarkable feature of the method is that it enables us to measure mutual friction of hairs and to evaluate the extent of harsh feel of hair during the washing process. Water was passed through the circular tube filled with the bundle of hair (a hair strand). The pressure drop of water was related to the frictional coefficient of hair. That is, the pressure drop decreases with decreasing fricional coefficient of hair. By this method we evaluated several groups of hair strands treated tivith different shampoos and rinses. The result was in accord with expectations based on the formula of samples and corresponded to the evaluation by expert panels. Thus, this new instrumental method was found to be very useful for comparing product effects on hair raspiness in the washing process.
Commercially available seamers for plastic tubes generally use heat or high frequency but they have such problems as difficult sealing if the internal surface of the tube is contaminaited with its contents. Particularly, when the tube content is viscous and has thread-forming properties or is of low viscosity and readily forms droplet the probability of defective sealing due to contamination increases resulting in consumers. The authors have initiated a study aiming at the development of a perfect sealing method even if the appropriate parts of tube are contaminated with the contents. In this study, heat sealing and high-frequency sealing wealing were not considered to be suitable to solve the problems and methods employing ultrasonic energy were examined under various conditions. Favorable results were obtained by the use of diagonal vibration as the vibration source and a honeycomb shape for the pattern.