Process for one-step colouring and straightening hair

摘要

The present invention provides a method which achieves a simultaneous coulouring and straightening of the hair in single step, utilizing a hair treatment composition comprising at least one carboxylic acid of formula (I) defined below and at least one direct dye: R-CO-COOH Formula (I) In another aspect, the invention is directed to the hair treatment composition and the use thereof for straightening and colouring the hair.