In pressing clay into moulds each part of the mould is used separately, except where only one mould is required, as in the case of an open bowl or tile. When the clay has been carefully pressed into every part of the mould, it is left to harden, and then, upon shrinkage, can be easily separated. If the vase has been pressed in several pieces, the parts must be carefully joined and the seams effaced as neatly as possible.
The Greek potter did not use moulding as a labor-saving device. He employed it only where the work demanded it, as in the Athenian plastic ware. Here we sometimes even find the same mould used several times, as in the group of a negro and a crocodile of which chance has preserved us at least five replicas[12]; but the number of such repetitions is not great and certainly would not indicate mass production.
Fig. 37. Inside of moulded vase
Met. Mus. Acc. No. 06.1021.205
The material of Greek moulds was burnt clay. That the Athenian plastic vases were pressed into moulds rather than poured can be seen from the fact that the insides of these vases are rough and show finger-marks (cf. fig. [37]). The joints of the two parts are clearly visible on many examples (cf. fig. [38]). Often the lip was thrown separately on the wheel and attached.
Fig. 38. Vase showing joint of two parts of mould
Met. Mus. Acc. No. 06.1021.203