The complete procedure consists of four parts: determination of the conditions for the preparation of the dispersion of the coloured pigment, and determination of the ratio of the coloured pigment to white pigment; preparation of the dispersion of the coloured pigment under defined conditions on an automatic muller; mixing the dispersions of coloured pigment and white pigment in a known ratio with a white pigment paste; the strength and undertone of the resulting reduction paste are compared with those of a similar paste made under the same conditions from the agreed reference pigment and the same white pigment paste. - This second edition cancels and replaces the first edition ISO 787/16-1973.