Hair Detangling Evaluation Method Using Section Detangling Rate

This study was conducted to objectively evaluate the degree of detangling needed to develop the effectiveness of cosmetic hair ingredients to prevent hair tangles. To evaluate the degree of hair tangling, the frictional force applied when combing the hair was measured. The tooth spacing of the comb used in the evaluation was examined, and it was confirmed that the 4 mm interval comb was suitable as there was a large difference in combability between different treatments and the deviation was small. To create samples to standardize hair tangles, spinning 25 cm or more of wet hair on a spinner for 5 min was found to be best for observing differences between treatments. In the case of hair shorter than 25 cm, tangles did not occur even when spun using a tool, but a suitable sample for evaluating tangles was obtained by rubbing the hair by hand about 15 times. When testing combability, the distance the comb moves until it reaches 9.8 N is considered to be proportional to the detangling efficacy, and the degree of tangling is evaluated based on the section detangling rate, which is the distance the comb travels to reach 9.8 N divided by the total tress length. As a result of evaluating the contact angle of tangled hair using an atomic force microscope (AFM) and a scanning electron microscope (SEM), it was found that the contact angle of the cuticle surface for the tangled part was larger than that of the straight part and the cuticle was damaged. After immersing tangled hair in rice bran extract containing six OH groups, the contact angle changed from 103° to 95°, which is the level of the straight part, and an increase in the section detangling rate of the hair was observed. As a result, it was suggested that the detangling efficacy could be evaluated by applying this evaluation method using the section detangling rate.