Black clay

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Black Clay, or "Barro Negro" is a traditional technique used in Oaxaca, Mexico for the production of pottery. Each pot or dish is hand-turned on inverted plates, dried in the sun and burnished with a stone or shard. The characteristic engravings and cutouts are carved at this stage. Next, the piece is fired in a smoky, low-oxygen kiln that imparts the distinctive black color to the naturally reddish clay.

Oaxacan black pottery is a traditional, indigenous, Zapotec art form principally practiced in Coyotepec, a village about twelve kilometers southeast of the town of Oaxaca. Black pottery varies widely in quality from slip-cast, mass-produced tourist goods to museum-class, detailed and finely finished objects. The raw clay is mined from a vein that the artisans say is chemically unique. They also say that at current rates of exploitation this vein will be exhausted in about fifty years. The prepared clay is a smooth, almost greasy material, very plastic and tan in color. The better articles are first thrown on traditional Zapotec pottery wheel, a pair of spherical, bowl-shaped plates, one balanced on the other without a pivot. The goods are embellished with intricate patterns, burnished smooth, then fired in a reducing atmosphere until the correct temperature is reached when normal, oxygen-containing air is admitted for a critical period of about five minutes. This produces the black coloration. Precise temperature and time definition is difficult because this process is an intuitive one, dependent on the skill of the Zapotec potters.