Influence of the thickness of the copper glaze layer on the color and its formation mechanism

In this paper, the effects of glaze layer thickness on the color properties of copper glaze were investigated, and the related mechanism was also revealed. The results manifest that the glaze thickness would affect the color of copper glaze. The color properties of copper glaze are determined by the phase-separated structure, the distribution of elements and the valence state of copper species. Due to the heterogeneous distribution behavior of the elements, the copper glazes with all thicknesses have three phase-separated structures, which are spherical (top layer), worm-like (interlayer) and nano-porous network-like (bottom layer). Simultaneously, the copper glazes with all thicknesses have three colors, of which the bottom layer of all samples is red. However, the color of the top layer gradually changes from milk white (0.2 mm) to cyan (0.4–0.6 mm) and then to blue (0.8–1.0 mm) with the green body thickness increases. The color of interlayer is the result of the color mixing of the top and bottom layer. A thicker green body thickness (>1 mm) could be propitious for copper glaze to present a superior color performance. This work provides a new and an easily overlooked perspective for the investigation of copper glaze.