A Study of the Photolightening Mechanism of Blond Hair with Visible and Ultraviolet Light
September 2004
in “
International Journal of Cosmetic Science
”
Studysummary This study demonstrated that visible light lightens blond hair more effectively than ultraviolet light, attacking melanin granules directly, whereas ultraviolet light primarily damages other hair tissues following washing. Our plain-language summary of this paper — not a Tressless recommendation.
The study investigated the photolightening behavior of blond hair under visible (VIS) and ultraviolet (UV) light. It was found that VIS light contributed more significantly to the lightening of blond hair than UV light, acting directly on the hair, while UV light required the hair to be washed post-irradiation to show lightening effects. Both VIS and UV light lightened isolated melanin granules similarly, indicating that melanin granules are equally sensitive to both types of light. However, UV light damaged hair tissues excluding melanin granules, whereas VIS light did not. The study concluded that UV light damages hair tissues, leading to lightening after washing, while VIS light directly decomposes melanin granules, lightening the hair without the need for washing.
