Testing of organic pigments

The method described is adopted in Farbwerke Hoechst AG for testing the colouring properties of organic pigments. The method closely follows the instructions for determining the relative tinctorial strength of coloured pigments according to DIN 53 204. It has been found to be necessary to make minor modifications in testing organic pigments. A pigment grinder of a specific type is used for the dispersion process. Depending on the dispersibility of the pigment, a known, readily reproducible degree of pigment dispersion is attained, which is comparable to that of a production batch after one to two passages on a triple‐roll mill. Somewhat different results may be obtained if different dispersing equipment is used.