PREDICTIVE ASSESSMENT OF HAIR STRUCTURAL CONDITION AS THE BASIS FOR PERSONALIZED SELECTION OF COLORING TECHNOLOGY

The global hair color market reached USD 28.1 billion in 2025 and continues to expand, yet a substantial proportion of coloring failures, including uneven pigment deposition, accelerated color fade, and fiber breakage, can be traced to the absence of structured pre-service structural diagnostics. This study examines the relationship between hair structural condition, fiber porosity, and degree of physicochemical damage on the one hand, and on the other hand the capacity of different coloring technologies to achieve stable, even pigment fixation. Through systematic literature synthesis covering peer-reviewed sources indexed in Scopus and Web of Science, complemented by analysis of instrumental diagnostic methods, a four-level Hair Structural Damage Classification is proposed together with a decision-support diagnostic framework mapping damage level to coloring technology selection. Results indicate that porosity-index-guided pre-treatment protocols can improve pigment fixation uniformity and reduce structural loss during coloring by a clinically meaningful margin. Findings are of practical relevance to professional colorists, salon educators, and cosmetic formulators working in the personalized hair care segment