Formulation Correction for Spot Color Inks Under Batch‐to‐Batch Variation of Substrates and Inks

ABSTRACT Batch‐to‐batch variations in substrates and primary inks pose significant challenges in spot color printing, often resulting in noticeable color inconsistencies despite consistent ink formulations. Existing solutions typically require recalculating optical properties for each new batch, a process that is both time‐consuming and resource‐intensive. This study proposes a formulation correction method based on the single‐constant Kubelka–Munk (KM) theory that compensates for batch‐induced deviations in the absorption‐to‐scattering ( K / S ) ratio. By utilizing the optical constants derived from a benchmark batch, the method estimates the K / S discrepancy caused by new batches and corrects the ink formulation accordingly, avoiding the need to remeasure optical properties. Experiments were conducted on five target spot colors using two batches of gravure inks and uncoated paper substrates. The proposed method improved color reproduction accuracy, reducing the average CIE ΔE from 2.05 to 0.97 and the RMSE of spectral reflectance across samples. Four out of five corrected samples achieved ΔE values below 1, indicating excellent visual consistency. This method offers a practical and efficient solution for maintaining high‐fidelity spot color reproduction in industrial printing workflows.