the present invention relates to a method of maintaining chemical reactivity of an oxidative hair colorant in an opened flexible sachet including a reclosure element . the quality of the re - closure will strongly influence how the hair colorant will perform when using it as intended . the method according to the present invention ensures maintaining chemical reactivity by improving the quality of the re - closure by intuitively inducing safe and tight re - closure by users of such hair colorant . this is achieved by providing the sachet to the user in a configuration already in its re - closure position , while the sachet has not been opened yet .