Design and Development of a Shampoo with Dark Semi-Permanent Dyes for Gradual Gray Hair Coverage

This study focused on creating a shampoo with dark semi-permanent dyes for gradual gray hair coverage. Four formulations were tested on bleached hair to evaluate color deposition and performance. The chosen formulation, containing dyes Basic Blue 124, Basic Yellow 87, Basic Orange 31, and Basic Red 51, showed stability in organoleptic, physicochemical, microbiological, and functional aspects. It effectively maintained a gray–black coloration on hair with 90% grayness after eight washes, demonstrating its potential for gradual cosmetic gray hair coverage.