5 citations
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October 2007 in “PubMed” Amino acids in conditioners improve hair strength, hydration, and color retention.
March 2011 in “Focus on surfactants” Several companies launched new hair care ingredients in 2011 to improve conditioning, color retention, combability, and heat protection.
6 citations
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October 2003 in “Journal of applied polymer science” A new method using poly(ethylene imine) improves hair dyeing at lower temperatures with better color retention.
January 2023 in “Fashion and textiles” Cationic and nonionic surfactants provide better color intensity and resistance for semi-permanent hair dye than anionic surfactants.
November 2025 in “Journal of Ayurveda and Integrated Medical Sciences” Herbal hair dyes are safe, effective, and beneficial for hair health.