Q. We measure our mid-gloss black color instrumentally, and we are having a difficult time correlating the instrumental color values to the visual perception. In many cases, we found that when a sample has a good instrumental correlation value to the standard, it does not look too good visually, and visa versa. What is the best way to evaluate a black color that has 60° gloss on 55–65 units? B.N.
A. Visual color perception is a complicated phenomenon. A complete explanation, both physical and psychological, of color perception is beyond the scope of Painting Clinic. Simply stated, color perception depends on a number of factors including the illumination of the subject as well as the age and condition of the eyes of the viewer. It is well known that even under the same illumination, it is possible that twelve viewers will give twelve different descriptions of the same color.
With these facts in mind, I recommend you do your color measurements instrumentally. However, if you must make visual determinations, have the same person perform the evaluations under the same light every time. This method applies to every color, not only black.
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Masking is employed in most any metal finishing operation where only a specifically defined area of the surface of a part must be exposed to a process. Conversely, masking may be employed on a surface where treatment is either not required or must be avoided. This article covers the many aspects of masking for metal finishing, including applications, methods and the various types of masking employed.