What is the best method to measure the opaque black color of a plasic material?
The best method is to measure spectral reflectance with a high-quality benchtop spectrophotometer. The benchtop instruments will usually have larger measurement apertures, more powerful light sources, and more sensitive detection systems in comparison with handheld instruments. These features will help to make the measurement of very dark colors more accurate and precise. The measured spectral reflectance can then be used to compute CIELAB coordinates to describe the color of the material.