What is the established color difference tolerance for the plastics industry?
There are not generally accepted standards for specific industries that suggests a single ΔE value as a standard. The tolerance is usually agreed upon between buyer and seller for the particular colors and applications in question. There are several issues that preclude use of such a simple tolerance. The first is the specification of the color difference equation to be used. Choice of a different equation (e.g. CIE94, CIE2000, CMC, or CIELAB) will result in differences in the perceptual magnitudes and characteristics of the stated Delta-E tolerance. The second is the dependency on color. For example, a CIELAB ΔE of 1.5 for a gray color is perceptually different from the same ΔE for a yellow color. This is part of what the newer equations like CIE94 and CIE2000 attempt to address. The differences between the various color difference equations and techniques for establishing meaningful tolerances with them are described in Chapter 4 of Roy Berns’ book, Principles of Color Technology, 3r
