Optical Properties of Hair: Effect of Treatments on Luster as Quantified by Image Analysis

In 2003, a study used image analysis to measure the luster of hair, which is the light reflected from a curved hair tress. The study found that the luster of hair increased in proportion to an increase in fiber pigmentation, meaning that darker hair had more luster. Cosmetic oils such as phenyl trimethicone, amodimethicone, and castor oil were found to increase the luster of hair due to a change in contrast between specular and diffuse reflection. Styling resins also increased hair gloss by a similar mechanism. However, the study also found that hair dulling occurred with the deposition of micronized ZnO at various concentrations and by synthetic sebum.