Ammonia remains the best agent to open the hair scales. To achieve significant lightening, or even bleaching, it must be incorporated into the formula. In oxidation colonies without ammonia, it is generally replaced by MEA (mono-ethanolamine), a milder and odorless alkaline agent… but a little less effective.
It mainly affects the exposure time. Each type of hair has a particular structure and diameter, which influence
the color result. The thinner it is, the less you need to force the scales open for the colon to set (=exposure time up to 10 minutes shorter). Ditto, if it is sensitized or very dry, the scales are already open, so the exposure time is shorter.
Thanks to Frédéric Mennetrier, colorist at Atelier Blanc and L’Oréal Professionnel expert, to Rodolphe Lombard, colorist at the Couleur par Rodolphe salon and to David Merveille, Schwarzkopf consultant hairdresser.
