The Study Of The Provenance Of Bohai Glazed Pottery

The glazed pottery of Bohai,which was produced in the eighth century,is mostly monochrome but sometimes polychrome.At present,no kiln has been found for firing such glazed pottery in the territory of the Bohai state.Owing to the fact that the glazed pottery of Bohai is similar to that of the Tang empire,commonly known as Sancai,in the Central Plain in shape,glaze and production technology,it is frequently compared with the latter.It is well known that the Bohai state maintained cultural and economic interaction with the Tang empire.In this historical context,whether Bohai glazed pottery was a local product or a goods imported from the Tang empire has provoked heated debate among scholars.The author collected samples of glazed pottery daily wares and building materials from the Shangjing and Zhongjing cities of the Bohai state.For comparative analysis,the author collected polychrome daily wares from the Tang production sites of Huangye in Gongyi,near the Luoyang city,and Huangbao in Tongchuan,near the Chang'an city.Samples of glazed pottery building materials and daily wares were collected from the Ximing Monastery,Taiye Pond,Sanqing Hall,in the Daminggong Complex and Bai Juyi's house,the Shangyang palace and Jiuzhouchi palace Site in Luoyang city.The author analyzed the composition of the body clay and the glaze and lead isotope of these samples at the Archaemetric Laboratory of School of Archaeology and Museology of Peking University.In addition,the author included the data of samples from the Tang production site of polychrome glazed pottery at Liquanfang,at the Chang'an city,and the data of samples from the Kraskino city of the Bohai state.As a whole,the samples of the Bohai state and the Tang empire occur in two types:daily wares and building materials;the question of the provenance of the glazed pottery of the Bohai state was approached from three angles:composition of the body clay,the glazing technique,and the lead isotope.From the analysis of the composition of the body clay,the source material of the glazed building materials of the Bohai state and the Tang empire is different.The clay of the samples of the Tang empire is mostly kaolin;only that of samples from Liquanfang is local high-iron and high-calcium clay.The glazed building materials are all made of high-iron clay,but the samples from the Shangjing and Zhongjing cities of the Bohai state are made of local sources of clay.The samples of daily wares from the Tang production sites at Huangye and Huangbao are made of kaolin,but those from Liquanfang are of local high-iron and high-calcium clay.Those of the Bohai state are mostly made of high-aluminum and high-iron clay,but some from Kraskino is made of high-altitude low-iron kaolin.It is likely that the cities of the Bohai state had their own production sites,which could mass produce building materials.However,the most demanding products such as daily wares are likely to be produced at certain sites with specific raw materials.From the perspective of the glazing technique,the Bohai glaze pottery may imitate Tang products,whose glaze is made by adding lead-silicon compound to kaolin and colorant.But for the daily wares and building materials,the glazing technique can be different.The glazing technique of the building materials is adding lead powder to the clay,but the composition ratios of the samples from the two cities of Shangjing and Zhongjing are different from each other.The Shangjing samples contain high percentages of lead,whereas the Zhongjing samples contain high percentages of silicon.The green glaze of the glazed pottery building materials in the Shangjing and Zhongjing is involved in color development by Fe element,and the Fe element comes from the local high-iron lava clay in Bohai.At the same time,in the glaze composition of Bohai State building materials,CuO is also contained.CuO also plays a partial coloring effect through the yellow-green glaze color of the building materials of the two city sites.The glazing technique of the daily ware samples is different,and that of the samples from the cities is likewise different.The glazing technique of the Shangjing samples is adding a lead-silicon compound to the local clay(the coloring with Fe in the clay).The Kraskino samples are glazed in two ways.Those of the samples with the local high-aluminum high-iron clay and the content of Al2O3 less than 24%is the addition of lead-silicon compound to the local clay.Those of the samples with body clay material similar to the Tang polychrome pottery and the Al2O3 content higher than 24%is the addition of a lead silicon compound to kaolin and a colorant(Fe2O3 or CuO).The glazed glaze is a glaze techniques in which a lead-silicon compound is added to kaolin and a colorant.The coloring agent Fe2O3 is an iron oxide having a high iron content.As the lead isotope data indicate,the sources of lead for the Bohai state samples are diverse.The lead materials of the Shangjing glazed pottery and building materials are likely to have come from the Tang production sites of Huangye and Huangbao.The lead material of the building materials from Zhongjing is believed to have come from Japan The lead of the Kraskino samples is acquired from multiple sources:Japan,Huangye,and Huangbao.The results indicate that Bohai may not have had access to the lead materials Consequently,it is surmised that the lead materials of the Bohai state are obtained through trade.In general,Bohai state should have the technology to produce lead glaze.The clay materials of Bohai pottery use local high-iron smelting clay or high-iron high-alumina clay.From the perspective of the glazing technique,the Bohai glaze pottery may imitate Tang products.The lead material comes from the Central Plains region or Japan,and finally is processed locally to form Bohai glaze pottery.At the same time,among the glazed pottery samples of the Bohai state and the Tang empire,some high-radiation lead was found,which provide new data for searching the source of high-radioactive lead in the Shang Dynasty bronzes.