In class 3 (_a_), or vases with figures on white ground, we have to deal with the process of covering the naturally pale clay with a white slip of more or less thick and creamy consistency, on which the designs were painted. In the archaic period this process is fairly common, especially in the earliest vases of Corinth and of Ionia, and at Kyrene and Naukratis. It was revived at Athens about the end of the sixth century (see pp. 385, 455). But when once the white slip was laid on, the technical process differed little from that in use on ordinary red-ground vases, except for the general avoidance of white as an accessory; it merely results that instead of a contrast of black and red, one of black and cream is obtained. The method was one also largely practised in early painting, as we see in the Corinthian pinakes and the sarcophagi of Clazomenae (pp. 316, 362). But there is another class of white-ground vases to which we must devote more special attention, namely, those on which the figures are painted either in outline or with polychrome washes on the same white slip. The earliest instance of such a method is in the series of fragments found at Naukratis, dating from the beginning of the sixth century (see p. 348), which technically and artistically are of remarkably advanced character, and combine the two methods of painting in outline and in washes of colour. In the fifth century the practice was revived at Athens as a means of obtaining effective results with small vases, and became especially characteristic of one class, the funeral lekythi, which are elsewhere described (Chapter XI.). This, however, must serve as the most convenient place for a few remarks on their technique. The vases, after they had left the wheel and were fitted with handle, etc., were covered with a coating of white flaky pigment, in consistency resembling liquid plaster of Paris, or, when dry, pipeclay. They received this coat of white while still on the wheel, and then a second coating, of the usual black varnish, was applied to such parts as were not required for decoration. Usually the white covered the cylindrical part of the body, and the shoulder up to the neck; black was applied to the mouth, neck, handle, base of body, and stem. The clay, it should be noted, is of the ordinary kind, but two varieties have been distinguished, one of pale red, for light thin vases, the other of a blackish-grey, for thicker and heavier ware. The natural colour appears on the inside of the lip and foot. Before being removed from the wheel the vases were finely polished, which gave to the white coating a sort of lustrous sheen; they were then fired at a low temperature.