To elucidate the compositions and chromogenic mechanisms of overglaze red pigment produced in the Jingdezhen kiln during the Ming dynasty, we employed energy-dispersive X-ray fluorescence spectrometry, Raman microspectroscopy, scanning electron microscopy, and single-factor simulations to analyse 16 specimens of overglaze pigment porcelain fired in the Jingdezhen kiln during the Ming dynasty. Results indicated that α-Fe₂O₃ crystals are the chromogenic agent in overglaze red pigments. However, the composition and crystallinity of the α-Fe₂O₃ crystals varied among specimens. Overglaze red pigment produced before the Chenghua era had a low Fe₂O₃ content and mostly exhibited a bright red hue, whereas those produced from the Chenghua era onwards had more diverse compositions and appeared bright red or dark red. The overglaze red pigment produced during the Jiajing era had high Fe₂O₃ and PbO content and were generally found to have a deep red hue. Simulation experiments indicated that increasing the calcination temperature of FeSO₄·7H₂O results in greater disruption of the long-range order of α-Fe₂O₃ crystals, thereby producing deeper hues of red. The results of the study will be of great significance for the conservation and identification of overglaze red pigment porcelain in the Jingdezhen kiln.

Keywords: Jingdezhen kiln, Overglaze red pigment, Chemical composition, Phase structure, Chromogenic mechanism.