Effectiveness of blue LED in enhancing hair treatments: Analysis in different hair ethnicities

Blue LED has several clinical applications, including enhancing the permeation of cosmetics into hair and enhancing hair treatments. This study evaluated its efficacy in these processes in different hair ethnicities, in addition to analyzing the changes in the physicochemical properties of the hair fiber after treatment. The study used virgin hair of Caucasian, African, and Asian types free from previous chemical treatments. Different application approaches with blue LED were adopted: spot application and sweeping application. For the analyses, six hair samples were prepared for each ethnic group, comprising: 1) Control without treatment; 2) Treated with leave-in cosmetic; 3) Treated with leave-in cosmetic and irradiated with blue LED in sweeping mode; 4) Treated with leave-in cosmetic and irradiated with blue LED in spot mode; 5) Untreated hair fiber irradiated with blue LED in sweeping mode; 6) Untreated hair fiber irradiated with blue LED in spot mode. Differences in cosmetic permeation into the hair strand after irradiation with blue LED were observed among different hair ethnicities. The Caucasian and Asian hair groups, when treated with cosmetics and irradiated with blue LED in the form of spot application and sweeping, showed a significant increase in cosmetic permeation, diameter, and resistance of the hair fiber compared to the African hair group.