We observe the sustainability of technical ceramics: the three operations which are essential for the production of a plastic clay remained roughly the same over the ages.
The washing and kneading of the earth are intended to provide uniformity necessary to expel foreign bodies, air bubbles. The simplest means is to trample the earth (marchage) or the fight.
The finishing first became entirely by hand from a flange land (colombin). The invention of the potter’s wheel driven by a rotational movement, which dates back at least to the first dynasty of pharaohs of Egypt (without being able to fix its exact date), can obtain objects plane circular perfect. The operation is more developed in two phases: ebauchage, which gives the form by the pressure of hands, and tournassage which refines and clarifies with a few tools. For parts of asymmetric shape or angular, it is necessary to deform after the shooting or return to the primitive method of colombin or proceed by casting. The parties annexes bottlenecks such as creeks, and so on. Are carried out separately and set out raw, the slip (clay delayee). The shaping by casting appears in the last years of the eighteenth century, this technique is to make the dough in the fluid in a plaster mold with a hollow shape of the piece to obtain. On contact plaster, water is absorbed by capillary it happens then filtered and the dough is deposited on the wall acquiring embracing all sinuosities plaster. The manufacture of plates and dishes is now in series with mechanical calibration.
The cooking ranges from simple drying in the sun, or over a wood fire in the open air, heated in ovens or earthen brick refractory. The temperature of cooking tends to rise, not exceeding 800 to 900 oC pottery tender for the sixteenth, seventeenth and eighteenth centuries, it may reach today for pasta hard over 1 400 oC. The first wood fuel, is still traditionally preferred by some manufacturers. However, the use of coal was introduced from the eighteenth century and heating coal became the nineteenth century. It will in turn gradually supplanted by heating gas, electricity, propane or oil. The cooking time, once set in a very empirical, is now adjustable. The ovens modern provisions varied depending on whether the furnace is intermittent derived from the old furnace globe, four cell, continuous or four ovens-tunnels. Through the latter, the trucks pass shaped parts for twenty-four to thirty-six hours or more.
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