This part of EN 13900 specifies a method of assessing the degree of dispersion of a colorant in a thermoplastic polymer. The method is suitable for testing colorants in the form of colour concentrates in all polymer used for extrusion and melt-spinning processes.The filter pressure value (FPV) determined according to this method is valid only for the equipment, conditions and test polymer being used. The use of test conditions differing from those specified may give different results. The method of preparing the colour concentrate is not specified in this standard. The results obtained for individual colorants are therefore comparable only when the same met