Practical study of qualitative and quantitative sebum excretion on the human forehead.

Measurement of Sebum Excretion Rate (SER) in patients is a time-consuming test. It is now possible to measure SER 1 h after having degreased the forehead with a 70% ethanol solution. The skin surface lipids (SSL) collected during this time have similar composition to those collected for up to 7 h. A qualitative and quantitative study of sebaceous excretion, on 18 volunteers, from 1 to 7 h after having cleansed the forehead, showed that the refatting kinetics, in all subjects, obeyed the same mathematical law, independent of the subjects' individual SER.