Purbeck Mineral and Mining Museum
After the closure of Eldon sidings all clay exports were via lorry. For several years the clay was carried from the mines across the A351 by trains to the "Lorry Drop". It was realised that the lorries could take the clay directly from the mines and the cost of maintaining a railway system avoided. The transhipment buildings were raised to accommodate the lorries beneath them and in the early 1970s the railway system sold partly into preservation and the rest scrapped. Use of narrow gauge railways continued underground at Norden No 6 & 7 mines until all mining operations ceased in 1999.
Japanese pottery and porcelain
Clay is chosen largely based on local materials available. There is an abundance of most basic types of clay in Japan. Due to naturally occurring kaolin deposits, many porcelain clays are found in Kyushu. Kilns were traditionally built at the sites of clay deposits, and most potters still use local clays, having developed a range of glazes and decoration techniques especially suited to that clay. The pottery clays found in the Japanese archipelago range from fusible earthenwares to refractory kaolins. From the Jōmon period to the Yayoi period, Japanese potters relied on high plastic iron-bearing shale and alluvial clays. Organic materials appear in much of the early Jōmon period work, but sand or crushed stone predominates thereafter. Further refinements came about under the Chinese influence in the 8th and 9th centuries AD, when creators of Nara three-color wares and Heian ash glazed wares sought out white, refractory clays and enhanced their fineness through levigation. In Kyoto, where demand makes it both practical and profitable, the clay is crushed, blunged (made into slip), and filtered commercially. To use the clay, you must first break it up into small pieces, pour a small amount of water over it, and beat it with a "kine", a wooden mallet, until you obtain the plasticity and uniformity of texture you want. Then you put it through an "aramomi" or "rough wedging" process, a kneading movement, after which the clay is stored for two or three days, or sometimes up to a week. Before the clay is ready to be thrown, it must pass through the "nejimomi" ("screw-wedge") process, which produces a bullet-shaped mass from which all air bubbles have been removed and in which the granular structure is arranged so that it radiates outwards from the center of the mass.