Empirical Evaluation of Color Shift Caused by Ultraviolet Coatings on Offset-Printed Coated Substrates

: In high-fidelity offset printing, maintaining colour accuracy is vital—particularly for applications such as illustrated books, packaging, and promotional materials. This study investigates the influence of post-print UV coatings—specifically UV-Gloss and UV-Matt—on colour stability across three types of coated media: Solid Bleached Sulfate (SBS) Coated One Side (C1S) paper, Gloss Art Paper, and Matt Art Paper. Using the CIE Lab* colour space and ΔE values as objective indicators of colour shift, printed samples of cyan, magenta, yellow, and black were analyzed before and after coating application. Pre-coated (Pre-Op) samples served as the baseline for comparison. The findings reveal that UV-Gloss coatings generally produce lower and more consistent ΔE values, especially for cyan and yellow, signifying better preservation of original colour tones. UV-Gloss was particularly effective on Matt and Gloss Art papers. Conversely, UV-Matt coatings consistently induced higher ΔE values across all paper types and colours, with black and yellow experiencing the most pronounced shifts. While UV-Matt coatings showed uniformity in their effects, their high ΔE readings suggest significant colour distortion. This empirical analysis offers practical guidance for printers, designers, and production managers seeking to balance print durability with visual integrity. The results underscore UV-Gloss as the preferred coating for applications where colour fidelity is paramount, while UV-Matt coatings are better suited for less colour-critical projects. The study contributes to optimized coating selection in print workflows, aligning aesthetic goals with technical constraints in contemporary offset printing.