Chromatic analyses on the visual perception of cadmium orange

Abstract

This article investigates the chromatic variations of the cadmium orange pigment (PO20) and their implications for the creative process in painting. The research, of an experimental and qualitative nature, stems from practical experience in outdoor landscape painting and studio work, extending to teaching, where discrepancies were observed between the results obtained with different brands of paint. The study compares six samples of oil paints with nomenclature related to cadmium orange, including genuine pigments (PO20) and their variations (PO20:1) and substitutes (mixtures of PY1+PR10 and PO43). The samples were tested in mixtures with Prussian blue (PB27) and titanium white (PW6), generating 420 color samples organized into six charts. The results demonstrate that, although theoretically opposite on the color wheel, the combinations between orange and blue produce significant variations of greens, violets, browns, and chromatic blacks, depending on the spectral inclination of the orange hue (more yellowish or more reddish). It is observed that pigments with the same Colour Index International code (PO20) may present distinct chromatic behaviors due to differences in supplier, calcination temperature, and the proportion of cadmium selenide. As a didactic contribution, the article proposes the "Chromatic Clock", a graph that assists in interpreting color temperature and opposition in pictorial practice. It is concluded that in-depth knowledge of the characteristics of each pigment is essential to avoid unwanted chromatic results and to expand the artist's expressive possibilities.