Terracotta and glazed terracotta
Clay is a moldable material but it requires great technical skills. Sculptors used it in diverse ways. The first conceptions or sketches of sculptures were often modelled in clay. The statuettes made as models for large-scale sculptures were also designed and fired from clay. This was particularly true in Italy. Painted and fired clay, so-called terracotta, was also used to decorate altars or as architectural ornamentation in Florence. From 1440 onwards, coloured and shiny glazed terracotta became a rival to marble, as it was less expensive.
First, the relief was modelled in clay and air-dried through careful rotation. Then it was fired in a woodstove without the covering glaze. Renaissance ceramics often had a yellow colour, which advantageously affected the colour of the subsequent glaze. Coloured glaze was applied by brush to the fired and cooled relief. Thereafter it was fired once more. During the second firing the glaze melted on the surface of the ceramics and became shiny. This resulted in the final colour of the relief.
(Workshop of Andrea della Robbia or Benedetto Buglioni: Adoration of the Child, inv. no.: 1172)