Etruscan earthenware pottery common in pre-Roman Italy chiefly between about the 7th and early 5th century BC. Characteristically, the ware is black, sometimes gray, and often shiny from polishing. The colour was achieved by firing in an atmosphere charged with carbon monoxide instead of oxygen. This is known as a reducing firing, and it converts the red of the clay, due to the presence of iron oxide, to the typical bucchero colours. Although opinions vary about the precise times at which certain features of bucchero appeared, there is a scholarly consensus about the overall development of the ware. The finest products, the light, thin-walled bucchero sottile, appear to have been made in the 7th and early 6th centuries. In these wares technique is excellent, form tends to be refined and controlled, and decoration, usually incised or in relief, is generally subordinate to form. The shapes and motifs of the mid- to late 7th century are derived largely from Oriental models, especially metalwork imported from Phoenicia and Cyprus. In the 6th century the influence of the Greeks emerges and forms change: alabastrums, amphoras, kraters, kylikes, etc., decorated with incised, modelled, or applied birds and animals in friezes or in association with geometric schemes appear. Decoration is sometimes limited to continuous bands of narrative figure reliefs, like those on painted Greek vessels. These were produced by rolling a cylinder with a recessed design over the soft clay. Eventually the Greek black pigment came to be used. Stylized human and animal figures were painted on the surface of bucchero in black, red, and white; and the black-figure style was expertly copied. Technique and workmanship declined from about the mid-6th century onward, when bucchero sottile was replaced by bucchero pasantë, a heavy, thick-walled ware, overly complex in form and ostentatiously decorated with reliefs.