Chinese Porcelain Collection
If you look carefully at this picture you will see all the stages in the clay preparation. Up front there are several basins with clay in different stages. Further back are the white porcelain clay bricks - the "Petunste", in most older litterature mistaken for the secret Chinese porcelain material itself.
Photo: © Jan-Erik Nilsson, 1992
The crushed stone powder then get watered down in rectangular water basins, about four by eight feet and some four feet deep. The finest clay powder settles on top of the cruder, and is floated over to another basin. The process is then repeated until all rocks are turned into fine clay which is then shovelled up and dried. While still plastic it is cut by a string and bow, and shaped into bricks in a simple four-sided boxlike wooden frame without bottom. The clay bricks are the dried in the shadow of the straw roof.
Modern standard clay is mixed in the proportions 1:4 of kaolin and porcelain stone. For higher quality they use a larger proportion of Kaolin. The "handmade" clays from the water mills are especially sought after for sculptures and hand throwing thanks to its higher plasticity. For this I take their word since I had no means to check this up. For future references I took samples of all the clays I saw, which are still in my possession.
Good supplies of raw materials are available at several places in the area. The basic idea of the porcelain clay is to mix one clay that melts around the particles of another clay, which does not melt at the firing temperature. Depending of the desired quality of the piece, glaze, decoration, hardness and the plasticity of the clay, and how the firing will be made (wood, coal or crude oil) the proportions are varied.
Text & Photos © Jan-Erik Nilsson, 1991, 1992, 2010
During 1991 and 1992 I had the privilege to visit the city of Jingdezhen and its surroundings as a participant in a small research delegation consisiting of Professor Bo Gyllensvärd, former head and founder of The Museum of Far Eastern Antiquities in Stockholm, two of the curators of Ulricehamn Museum of Oriental Art and the Carl Kempe Collection, and myself. All pictures illustrating this article are taken by me during those visits.