CIELAB substrate and ink parameters influence on ink fluorescence intensity

Abstract

The article presents the illuminance of eight fluorescent inks in the context of colour CIELAB parameters. The tested fluorescent inks include the most commonly used colors in the white light spectrum, from blue-violet to intense orange. These inks contain 30 % of fluorescent pigments. The illuminance analysis of the ink films covers a wide range of ink layer thicknesses, the type of substrate (without and with optical brighteners), and the substrate CIELAB lightness from white to black used to obtain prints. The article derives the dependencies of the ink illuminance excited by UV radiation on CIELAB parameters, including the lightness of the substrate (L∗_s), the lightness of the fluorescent ink layer (L∗_ink), and the a∗ and b∗ parameters in the CIELAB space. In all cases, these dependencies have the nature of an exponential function and significantly impact the fluorescent effect. The novelty of the presented results is the possibility of an appropriate selection of the thickness of the ink layer, the ink colour, the substrate, and the substrate lightness to obtain desired ink illuminance. The research results may find application in many industries where fluorescent inks are used, particularly in the case of evacuation routes, safety signs, security printing, and various types of sensors.