Methods of test for paints - Optical tests on paint films - Determination of contrast ratio (opacity) of light-coloured paints at a fixed spreading rate
This part of ISO 6504 is one of a series of standards dealing with the sampling and testing of paints, varnishes and related products. It specifies methods for determining the opacity (by contrast ratio measurement) given by paint films of white or light colours of tristimulus value Y greater than 25, applied at a spreading rate of 20 m/l to an agreed black and white chart or to colourless transparent polyester foil, in the latter case the tristimulus value Y being measured subsequently over agreed black and white glass panels.