The invention relates to a hair treatment applicator for applying a hair treatment product composition to a user's hair by passing the applicator through the hair in a predetermined direction, where the applicator comprises a handle and a head connected to the handle, where the head includes a body having a base and a retaining structure, the retaining structure comprising a pair of opposed blades extending downwardly from the base and proximate the edges of the base, the pair of opposed blades being disposed coincident with the direction of use and the opposed blades defining a retaining volume adapted to receive the hair treatment product composition.