How to Make Semi-Permanent Hair Dye Permanent: Safer Options
You cannot chemically turn semi-permanent hair dye into permanent color at home. Semi-permanent, or direct, dye deposits pre-formed pigments on and near the hair cuticle, while permanent color uses oxidation to develop dye molecules inside the cortex. You can extend direct-dye color to roughly 4-8 weeks by controlling porosity, application, rinsing, heat, and washing. Key […]