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Monday, December 7, 2015

Color Difference: CMC and the Commercial Factor

The CMC Color Difference Formula (below) is very good at defining tolerances that are directly related to how people see color and accept matches. The tolerances that are created are ellipsoid (left). Therefore, all samples which fall inside the ellipsoid are deemed acceptable and all samples which fall outside the ellipsoid are rejected.  

Here is some brief information on how tolerances can be set for production (pass/fail) purposes. CF, commercial factor, is a number that converts the “just acceptable” ΔE*CMC to a value that is 1.0. In other words:

Our customer must know what a “just acceptable” ΔE*CMC is, which will typically vary depending upon their customer. Once that is known the CF can be determined and entered into the ΔE*CMC set up table. From that point on, if