Color Cast in dark areas, especially in Rich Black, occurs when the rich black formulation is excessively skewed toward one of the CMY components (usually Cyan, which leads to a blue tint). The goal of adding CMY to the black (Key Color) is to increase visual depth, but excessive or unbalanced addition deviates the final black from a neutral gray toward a dark blue or purple. Consultants emphasize that only visual assessment under non-standard light can lead to the approval of a Rich Black with a color cast, whose flaw will be evident in other environments.

To prevent this issue, the Rich Black formulation must be adjusted within the permitted Total Ink Coverage (TIC) range and with a balanced CMY alignment. Standard formulas generally use low to medium CMY concentrations (e.g., C:40 M:30 Y:30 K:100) to ensure the black color base is a completely neutral gray. Precise establishment of the White Point at the start of the process and continuous use of a Standard Illuminant for final inspections are key actions that guarantee brand color consistency. This approach solves the color cast problem at the print inspection stage.