Ammonia remains the most effective agent for opening the hair cuticle, enabling deep pigment penetration. For substantial lightening or bleaching, it’s essential in the formula. Ammonia-free oxidative colors typically use monoethanolamine (MEA) instead—a milder, odorless alkaline agent that’s slightly less powerful.
It primarily influences processing time. Hair varies in structure and diameter, impacting the outcome. Thinner hair needs less cuticle opening for pigments to deposit (up to 10 minutes shorter exposure). The same applies to sensitized or very dry hair, where cuticles are already raised, reducing development time.
Thanks to Frédéric Mennetrier, colorist at Atelier Blanc and L’Oréal Professionnel expert; Rodolphe Lombard, colorist at Couleur par Rodolphe salon; and David Merveille, Schwarzkopf consultant hairdresser.
