. When is it necessary to lighten eyebrows? Either to achieve the desired natural colour (4N to 9N) as basis before tinting with RefectoCil No. 4 chestnut and No. 4.1 red in order to intensify the subsequent tinting result and therfore enable a perfect match with client’s dyed hair; or to match too prominent or dark eyebrows with bleached/dyed blond hair. CAUTION: RefectoCil Bleaching paste No.0 blond must not be mixed with any of the RefectoCil colours! For detailed instructions for use and application tips go to RefectoCil Bleaching paste No.0 blond.