Study of the re-oiling process of hair with the replica technique

Synopsis In the case of individuals with oily hair, the sebum excreted to the scalp surface spreads over the hair during the days following hair washing. The migration of sebum from the roots to the ends of hairs creates a gradient which may be measured by making casts on appropriate materials. An optical reading device enables the assessment of the alterations of the material brilliancy as a function of the sebum presence. The following parameters may be assessed from the recording: length of the cast, surface, height and width of the peak. Thus, different types of oily states may be identified according to: - the number of days after the last shampoo; - the characteristics of sebum (e.g. quantity, viscosity); - the features of hair. The casts reflect the oily state of hair as accurately as if it were assessed with a sensory method. Thus, this technique enables the study and comparison of oily states. It can be used to determine the efficacy of products having an effect on the re-oiling process of hair.