Terra Cotta, California
Coal, along with clay deposits, was found on the site by John D. Huff in the late 1880s, and the Southern California Coal and Clay Company was formed to mine them. The town site of Terra Cotta was laid out and was given a post office on October 26, 1887. In May 1893 its post office was closed and moved to Lake Elsinore. A plant for the manufacture of sewer and water pipes was built using the coal to fire ceramic pipes in the four kilns. The finished product had to be shipped by wagon six miles through Lake Elsinore to the La Laguna rail station at the mouth of Railroad Canyon until 1896 when a spur line was built through Lake Elsinore and Terra Cotta to the new clay deposits in Alberhill. The coal mined was also used locally as fuel for the stamping mill at the Good Hope Mine and was shipped elsewhere in the state.
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.