Yixing: The Clay Pt. 4

The drive way of the big pot museum was lined with mill stones stacked on their sides. From the pictures above you can see how massive the stones are. Their circumference varied based on how long each was in use. The older method of mill stone grinding involved a horizontal rotary system. Mule or human power would have been used to turn small mill stones that lay on top of each other. A more recent method involved a mechanical dual stone system. In this method two vertical stones roll slowly around a lower horizontal stone. The compression crushes the parent rock into a fine dust. After the stone is pulverized it would be soaked in settling ponds for many years before it could be worked to a plastic state.

I am fascinated by the geologic time it takes for clay to become workable. The parent rock for Yixing clay is a sedimentary stone local to the Yixing area (the striated rock pictured above). Over hundreds of thousands of years igneous rocks from local mountain ranges were eroded by wind, rain, and the freeze/thaw cycle. Over thousands more years this erosion collected in low lying areas where it rehardened. In total we are talking about a process that stretches over millions of years. This is mind boggling to me. I touch clay everyday but I rarely consider the time it took to come into being.

Over the process of erosion and sedimentation the Yixing clay picked up large amounts of Iron. This coupled with trace amounts of Manganese give the clay it's unusual purple color. Their are many clays in the world but few have the same purple mixture of colorants. For my fellow tech nerds I have included a chemical analysis and a list of comparable terracotta clays in China.

Seeing the process of preparing the clay was a fitting end for my trip to Yixing. We saw so much in one day but I left feeling like I saw so little. Every studio had a new technique or piece of history that I want to absorb. I will try to visit the area again before I leave China.

This post is the final in a series about Yixing teapots. They are produced in the town of Dingshan, which borders the city of Yixing in Jiangsu Province. 

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