Optical transmittance mechanisms of white pigments in chromatic expression of copperplate prints

White pigments are rarely employed as standalone elements in printmaking, primarily due to their susceptibility to discoloration and fading during both the printing process and long-term preservation. This study examines the influence of two white pigments—titanium dioxide (TiO2) and zinc oxide (ZnO)—on color development and adhesion in copperplate prints. Through controlled experiments, we demonstrate that the wavelength of transmitted light significantly affects ink drying rates, thereby altering the chemical environment of cured ink layers. Furthermore, substrate composition (particularly cotton content) and residual byproducts from etching processes were identified as critical factors contributing to pigment degradation. These findings reveal the intricate interplay between material properties and technical variables in printmaking, emphasizing the necessity of precise environmental and compositional control to maintain color accuracy and durability in printed works. This research may also offer valuable insights into the conservation and preservation of copperplate prints.