GB/T 5211.19-1988 "Determination of relative tinting strength and reduced colour of coloured pigments - Visual comparison method" specifies a visual comparison method for determining the relative tinting strength and reduced colour of coloured pigments, applicable to various types of coloured pigments. The test involves mixing dispersions of the sample and a standard pigment separately with a white pigment paste to prepare reduced colour pastes, followed by comparing the colour intensity under a standard light source. The detection requires equipment such as a levelling machine, wet film applicator, standard light source box, and palette knife. The method is simple to operate and provides a means for rapid evaluation of the colouring properties of pigments.