Evaluating Mid-Gloss Black

Q. We measure our mid-gloss black color using a color difference meter. We are having a hard time correlating the instrumental color values to the visual perception of the finished black paint. In many cases, we found that when a sample has good instrumental color match to the standard, it does not look good visually, and vice-versa. What is the best way to evaluate the black color, which has 60° gloss of 55–65 units? B.N.

 

A. It is well known that each person will perceive the color differences between a painted surface and a color standard differently. These discrepancies from person to person are due to varying ocular pigmentation, varying concepts of what is a good color match, training and experience. The other notable phenomenon is the effect of different glosses on color perception. In the early 20th century, these differences were recognized and led to the concept of the Standard Observer.

This was recommended in 1931 by the International Commission on Illumination (CIE). Simply stated, the spectral response of the standard observer is defined by the tristimulus value, X (red), Y (green) and Z (blue). Space does not permit a complete explanation of this concept. Although this early work by the CIE and the establishment of the Standard Observer concept had some deficiencies, it ultimately led to the development of the modern color difference meters that we use today.

With this in mind, you are faced with two choices. You must either train one person to be your color expert or rely on instrumental measurements. The problem with the color expert choice is, what to do when he is sick or on vacation? Owing to the aforementioned color perception of different people, I suggest you use your color difference meter for these measurements.