The glaze was applied to raw pots, which were then fired in a reduction atmosphere, a term I’ll explain shortly.
Although much pottery was made in the Middle East, Oriental cultures contributed most directly to the refinement of pottery as a craft. Some of the earliest glazes the Chinese used were celadons, which were made from the same clay as the pots, combined with wood ash. The glaze was applied to raw pots, which were then fired in a reduction atmosphere, a term I’ll explain shortly. In the Orient, different regions had unique types of celadons, due entirely to differences in the composition of local clays. Clay that contained trace amounts of lime produced celadons that turned blue—the classic Chinese celadon. Classic Korean celadons were pale green, and classic Japanese celadons were olive green. The clay contained a small amount of iron, and the wood ash contributed lime and silica to the glaze. Combined with the right atmosphere in the kiln, the glaze would turn the translucent, pearl-like blue or green color that Oriental potters are famous for.