The present invention relates to dyes of the general formula CAT+ Y− (I), where Y− is an anion selected from the group of the cyanoborates, fluoroalkylphosphates, fluoroalkylborates or imidates and CAT+ is a cation selected from the group of the azine, xanthene, polymethine, styryl, azo, tetrazolium, pyrylium, benzopyrylium, thiopyrylium, benzothiopyrylium, thiazine, oxazine, triarylmethane, diarylmethane, methine, acridine, quinoline, isoquinoline or quaternary azafluorenone dyes, for colouring plastics and plastic fibres, for the preparation of flexographic printing inks, as ball-point pen pastes, as stamp ink, for colouring leather and paper, for use in data acquisition systems, reprography, in ink microfilters, in photogalvanics, laser technology and the photo industry.