Investigation of penetration abilities of various oils into human hair fibers

In the study titled "Investigation of penetration abilities of various oils into human hair fibers," researchers explored the capillary adhesion between hair fibers treated with different types of oils, including coconut, olive, sunflower, and mineral oils. They found that capillary adhesion decreased over time when using coconut, olive, and sunflower oils, but not with mineral oil. Application of heat further reduced capillary adhesion for coconut and sunflower oils, but again, not for mineral oil. Based on previous studies showing that coconut oil could penetrate hair while mineral oil could not, the researchers hypothesized that the reduction in capillary adhesion was due to the penetration of oil into the fiber, which left a thinner oil film on the hair surface. This hypothesis was supported by goniophotometric measurements on single hair fibers, which showed that as the oil is absorbed into the hair, the film thins and the scale structure of the hair reappears. The study concluded that the reduction in capillary adhesion between hair fibers is likely due to the absorption of oil into the hair.