greater the quantity of pigment used the deeper the shade of color produced the operator of the process should determine by trial the precise quantity and type required to produce the target color the manufacture of dispersions in accordance with the invention is performed in well known manner e g by grinding a concentrated mixture comprising a dispersion agent a dispersion medium and compound s of formula i e g in a ball sand glass bead or quartzite mill until the size of the undissolved particles lies in the average of 0 5 5 mu m preferably 1 mu m and if necessary by the adjustment of the desired concentration as a result of adding a dispersion medium which is preferably water many of the pigments used to color polymeric articles are supplied by their manufacturer in the required particle size for use in the invention in general the dispersions in accordance with the invention contain 10 60 weight percentage preferably 15 50 weight percentage and in particular 20 40 weight percentage of a compound or a mixture of the compounds of formula i or and ii 4 50 weight percentage preferably 5 45 weight percentage and in particular 6 35 weight percentage of a dispersion agent based on the weight of the flame retardant pigment the remainder.