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.
Conservation and restoration of ceramic objects
Additionally the type of ceramic will affect how it will break down. Unfired clay, like mud and clay adobe, is clay that is fired under 1000 °C or 1832 °F. This type of clay is water-soluble and unstable. Earthenware is clay that has been fired between 1000-1200 °C or 1832°-2192 °F. The firing makes the clay water insoluble but does not allow the formation of an extensive glassy or vitreous within the body. Although water-insoluble, the porous body of earthenware allows water to penetrate. A glaze can be applied that will protect the vessel from water. Due to its porosity, earthenware is susceptible to moisture and creates problems including cracks, breaks and mold growth. Porcelain and stoneware is fired at the highest temperatures between 1200-1400 °C or 2192-2552 °F. Porcelain clay mixtures are fired to create a non-porous and very hard surface. However, the materials also create a very brittle surface which increases the potential for chips, cracks and breaks.