Black coal cinder ceramics: an unusual technological choice in Sichuan Province, China

Abstract

In Sichuan Province, China, many workshops on the historic pottery street of Yingjing and one small one in Gaoxian produce black pottery by adding ground coal cinders to their clay. This unique raw material is fired with a kiln design and process that are also unique. Coarse-grained cooking products are most common, but fine-grained teawares and other new product lines recently emerged in Yingjing to meet new market niches. High-temperature phases such as mullite, cristobalite, and glass seen in thin sections primarily reflect those also seen in the coal cinders. The volume of closed and open pores and the structure of pore systems differ for coarse versus fine wares and are well suited for intended product functions. Variation in pore systems for Yingjing coarse wares indicates subtle differences in raw materials, materials preparation, and firing temperatures between workshops and within each workshop’s numerous production runs and products compared with the sole Gaoxian small workshop with very limited products.