Characterization of Angle Dependent Color Travel of Printed Multi-Color Effect Pigment on Different Color Substrates
Color-travel pigments, which exhibit much more extensive color change as well provide angle-dependent optical effect can be used in many industrial products. In present paper the multi-color effect pigment printed on three different foils with different background color (black, silver and transparent) was investigated. The pigment was based on synthetically produced transparent silicon dioxide platelets coated with titanium dioxide. CIEL*a*b* values and reflection of prints were measured by multi-angle spectrophotometer at constant illumination at an angle of 45o and different viewing angles (-15o, 15°, 25o, 45o, 75o and 110o) were used. The measurements of printed multi-color pigment showed that CIEL*a*b* color coordinates varied to great extents, depending on detection angles as well on color of the printing substrate. The study revealed that pigmnet printed on black background obtained significant change in color. The study has also shown that when viewing angle increases, the reflection curves decreases.
Use of effect pigments for quality enhancement of offset printed specialty papers
Nowadays, effect pigments are widely used in many printing industries. The colorful effects produced by light scattering of these types of pigments add an additional value to the prints and enhances the overall quality of color appearance. The aim of this study was to investigate the quality enhancement of printed specialty papers with various effect pigments in combination with offset inks. Four different effect pigments were used (one luster pigment-EP1, two interference pigments-EP2, EP3, and one multicolor pigment-EP4) as well as two types of paper substrates (film synthetic paper and wood-free paper). The effect pigments were overprinted on dried CMYK offset prints on both paper substrates. The following analysis were performed: scanning electron microscopy analysis of effect pigment particles, contact angles of papers and offset prints, Fourier transform infrared spectrocopy (FTIR), principal components analysis (principal components analysis (PCA)), and flop index analysis of overprinted effect pigments, and paper and print gloss. The results of the experiment indicate that effect pigments behaved differently on different printing substrates. From the FTIR and PCA, it was found that the different composition of effect pigments differently influence the behavior of these particles on the final prints. Effect pigments overprinted on offset CMYK inks on both paper substrates enhance print gloss, except interference pigment EP2 on film synthetic paper. It was also found that the ink color has the most pronounced influence on flop index, followed by the papertype and the type of effect pigment. Higher flop index was obtained at wood-free paper, especially by overprinted pigment EP2. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 168–176, 2013.
Color measurements for pearlescent coatings
This article describes recent developments at the National Institution of Standards and Technology in the colorimetric characterization of pearlescent coatings. The goal of this research is to develop a measurement protocol for the accurate color characterization of these coatings using an understanding of their scattering mechanism as a guide. A large ensemble of bi-directional reflectance measurements on a series of pearl interference pigmented coatings show general trends in the color variations with illumination and viewing angles. These measurements were used to define a set of geometries (illumination angles of 15°, 45°, and 65° and aspecular angles of 15°, 35°, 45°, 70°, and 85°) to characterize the angle dependent color travel observed in these coatings. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 38–42, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10210