This part of this European Standard specifies a method of determining the colouristic properties of a test pigment relative to a standard, and the ease of dispersion DHPVC-P of pigments from the differences in colour strength on dispersing colouring materials under various conditions in plasticized polyvinyl chloride (PVC-P) compounds. The method is appropriate for use with organic and inorganic black and colour pigments and for pigment preparations. The ease of dispersion determined in this way is valid only for the dispersion equipment, dispersion conditions and dispersion medium being used. The use of test conditions differing from those specified may give different results; this applies both to the absolute magnitude and to the relation between values of the ease of dispersion of various pigments. The subscript DHPVC-P is therefore used to designate the value obtained as specified in this part of this European Standard. The principle of this standard may also be used for routine quality control purposes by reference to the photometric data generated from the sheets milled at 130 oC. For quality control purposes, the ratio of pigment to TiO2 may be agreed between the interested parties. Ratios of 1:10 for organic pigments and 0,2 to 0,5:1 for inorganic pigments are suggested as convenient and widely used standard ratios. Annex A is informative and gives a description of a suitable basic compound.