This part of ISO 8780 specifies a method for the dispersion of pigments and extenders using a triple-roll mill. The results permit conclusions to be drawn as to the behaviour of the products tested when dispersed using corresponding production machinery. This part of ISO 8780 is for use in conjunction with the methods of assessment described in ISO 8781, using an agreed binder system of high viscosity free from volatile materials. It should be read in conjuction with ISO 8780-1. This method is restricted to high-viscosity mill bases. To improve the precision of the method, it is recommended that the dispersion procedures for the test pigment and agreed reference pigment are carried out at the same temperature. The results obtained are not suitable for making comparisons with dispersibility results obtained using other methods of dispersion. NOTE 1 The advantages of the triple-roll mill described in this part of ISO 8780 lie in the ease of handling of the equipment, the possibility of preparing adequate quantities of mill base for extensive evaluation procedures, the ease of cleaning and the possibility of correlating the results with those from production machinery. Unlike dispersing equipment for low-viscosity mill base formulations, a triple-roll mill of the kind described in this part of ISO 8780 permits the processing of mill base formulations within a wide range of high viscosities. Owing to this greater flexibility, precise specification of suitable mill base formulations is unnecessary