Ughill
The fire brick company Thomas Wragg & Sons owned a Pot Clay mine immediately to the south east of the hamlet. Pot Clay is the impure version of Ganister and was in demand in the Sheffield steel industry to make bricks for the lining of furnaces. In the early 1970s the mine was producing 15,000 tons of clay per year, with the company quoting, “The mine can be worked at the present rate for 100 years”. A refractory brick works stood at the entrance to the mine. However the Ughill mine had drainage problems and although powerful pumps had been installed in the 1950s to pump between 600 and 800 gallons per minute from the mine, the mine closed on 17 November 1977. It had become uneconomic to mine the clay due to water problems and the owners found it more profitable to bring in clay from the Midlands. The site of the mine has been landscaped and returned to agricultural use. J&J Dyson mined fireclay at their open cast quarry at Wheatshire between Ughill and Sugworth. The quarry is closed but can still be seen from the nearby road. Thos. Wragg had small firebrick works at Load Brook (closed 1957) and Brookside (Stopes Road, Stannington, closed 1960) the former previously owned by the Trickett family, the latter by the Drabble family and a major works (Old Wheel Brick Works) in the nearby Loxley Valley. Wraggs along with its local competitors, J&J Dyson of Griffs Works, Stannington and Thos. Marshall of Storrs Bridge Works, Loxley, mined the Stannington Pot Clay seam and manufactured fireclay-based casting pit holloware refractories for use in steel making worldwide. All three plants closed following a collapse in demand for casting pit refractories of the type made locally mainly because of the introduction of continuous casting of steel worldwide and the general demise of the British steel industry.
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.