This part of ISO 23900 specifies a method assessing the degree of dispersion of colorants1) and/or extenders in a thermoplastic polymer. The method is suitable for testing colorants and/or extenders in the form of concentrates or compounds in all polymers used for extrusion processes. NOTE Defects such as gels, black specks, holes in the test film are not in the scope of this part of ISO 23900. The film test result 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 might give different results. The preparation methods of concentrates or compounds are not specified in this part of ISO 23900. The results obtained for individual colorants and/or extenders are therefore comparable only when the same conditions of preparation for concentrates or compounds and a comparable detection system are used.