A Study of the Techniques Used to Make Laohudong Guan Ware in China in the Southern Song Dynasty

摘要

Through a combination of analysis and synthesis of Laohudong Guan ware shards from Hangzhou City in southern China, some new hypotheses concerning Guan ware manufacture can be proposed. These suggest that the complex microstructures seen in Guan ware glazes, and which contribute significantly to their jade-like qualities, may owe much to layers of fine bubbles trapped during the glazing process. It is also proposed that the multi-layer glazing methods used at the Guan ware kilns at Hangzhou may have helped initially to disguise the relatively coarse and ferruginous clays used for Guan ware manufacture. Once established, the layered glazing technique was used for its own sakeeventually yielding wares that could comprise more glaze than clay. Raw materials and firing temperatures were also explored for this study, and these suggest the use of porcelain-stone/wood ash mixtures for glaze-making, with 20-30% calcareous wood ash being the usual amounts. The average heat-work for the glaze firing seems to have been equivalent to Orton Cone 7, giving a typical finishing temperature of approximate to 1215 degrees C. A single biscuit firing and a single glaze firing seem likely for most Laohudong Guan wares. Studies of the losses that occur in the preparation of calcareous wood ashes suggest that very large quantities of botanic material must have been burned to provide ash for glaze-making at the Laohudong kiln. From the environmental perspective, a combination of thick glazes and heavy wood-ash usage would have placed great demands on local fuel supplies.