Kiln change refers to the process in which the glaze of porcelain is fired at high temperature and the products obtained after opening the kiln have obvious changes in glaze and enamel due to the oxidation-reduction of various color elements, and it is difficult to tell the reason and repeat the results.
The familiar kiln change began with Jun porcelain. Jun glaze layer is thick. Using 0.5% - 0.9% copper oxide as colorant, it can be reduced to colloidal copper particles and form red glaze in the reduction flame above 1200 ℃. Due to the different sizes of copper particles, or the mixture of cyan and red, sometimes it presents rose purple and Begonia red glaze. Because this is a very complex process of firing porcelain. If the composition of the glaze is uneven, or if two kinds of glaze with different properties are applied to the same porcelain, the kiln will change due to the complexity and unpredictability of the change. In this sense, whether kiln change can occur in a certain firing atmosphere is closely related to pigment molecules, color rendering mechanism and glaze color quality.