COMPOSITION FOR DYEING KERATIN FIBRES COMPRISING A DIRECT DYE BEARING A DISULFIDE/THIOL FUNCTION, A NONIONIC SURFACTANT, AN AMPHOTERIC SURFACTANT, AN ALKALINE AGENT AND A REDUCING AGENT
The invention relates to a process for dyeing and/or lightening keratin fibres such as the hair, using i) at least one direct dye bearing a disulfide, thiol or protected-thiol function and ii) at least one nonionic surfactant, iii) at least one amphoteric surfactant, iv) at least one alkaline agent, and v) at least one reducing agent. The invention also relates to a composition comprising the ingredients i) to v), to the use of the combination of i), ii), iii), iv) and v) for the dyeing and/or lightening of keratin fibres, and to a multi-compartment kit comprising the ingredients i) to v). The dyeing process and the composition according to the invention especially afford a long-lasting coloration on keratin fibres, which is strong, chromatic and/or homogeneous, with or without the use of an oxidizing agent.