Evaluation of post-application rheological changes in cosmetics using a novel measuring device: relationship to sensory evaluation.

Abstract

application, and the relationship of the results to subjective sensory evaluation was examined. The device can measure the frictional force (0.001-0.1 N) between a probe and the surface of the sample stage, which moves reciprocally at a constant speed (1-8 cm/s). Two different probes (block-type and roller-type) were used under a constant load (0.02-0.3 N). The relationship between frictional force and the spreading resistance was examined using massage gels with the block-type probe. The changes in the measured force with the block-type probe correlated well with the changes in the spreading resistance experienced upon massaging the skin. This indicates that the spreading properties of cosmetics can be evaluated with this device. With respect to stickiness, no clear correlation was found between the measured frictional force and the skin sensation of moisturizing creams and essences using the block-type probe. With the roller-type probe, however, the stickiness of cosmetics due to thickening of polymers, oils, and other ingredients after application to the skin was reflected in the friction curves. The frictional force at 10 min correlated with the post-application stickiness.