Terracotta, meaning ‘baked earth,’ is clay that has been fired in a kiln. The affordability and durability of terracotta meant it could be used in a wide range of applications. Monastic orders which valued poverty appreciated clay for its humble origins. Popular piety also helped create a market for affordable religious images. Sculptors often made plaster moulds of their sculptures and produced multiples to sell, making custom changes along the way. Despite its affordability, commissions for terracotta sculptures were not always humble projects. Some were painted with expensive, imported pigments, and lined with real gold. A Madonna and Child relief, attributed to Lorenzo Ghiberti, Filippo Brunelleschi, and Nanni di Banco, features extensive use of gold leaf that would have created a glittering, golden surface. To the uninformed viewer, surface treatments such as these meant it was no longer evident whether a sculpture is of clay, wood, or stone. Clay’s physical malleability also made it an ideal medium for modelling hair, skin-like textures and facial expressions. See, for example, the soft skin of the Baby Jesus, and the cascading locks in the Man of Sorrows. Meanwhile, the various, energetic expressions and gestures in the Mocking of Christ help bring the dramatic scene to life.
How were they made?
Tuscany’s numerous river beds were abundant sources of clay for sculptors, potters and brickmakers. Industry professionals could assess the quality of clay from its colour and texture. If needed, they mixed additional substances, like sand, to improve the clay’s workability. Clay naturally dries and hardens in the air; to keep it soft and malleable, sculptors put wet cloths along the surface as they worked. It was essential to ensure the clay had an even thickness throughout to prevent it from cracking during the backing process. In the kiln, clay hardens and shrinks irreversibly, transforming into a resilient material suitable for both indoor and outdoor use. The ideal firing temperature varies according to the type of clay, ranging anywhere from 900 to 1200°C (1652° – 2192°F). Depending on the type of paint, terracotta sculptures were first primed using gesso. The basic components of gesso are a binding medium (e.g. linseed oil, egg whites) and white pigments (e.g. chalk, gypsum, white lead, or lime). For gilding, a popular primer was a greasy clay called Bole, which helped the gold or silver leaf adhere to the surface. Pigments that were purchased as a dry powder could be further refined by grinding on a stone slab made of porphyry or marble.
Daria Melnikov
Selected Bibliography
Boucher, Bruce. “Italian Renaissance Terracotta: Artistic Revival or Technological Innovation?.” In Earth and Fire: Italian Terracotta Sculpture from Donatello to Canova, edited by Bruce Boucher. New Haven and London: Yale University Press, 2002 ; Helms, G.M. “The Materials and Techniques of Italian Renaissance Sculpture.” In Looking at Italian Renaissance Sculpture, edited by Sarah Blake McHam. Cambridge: Cambridge University Press, 1998. ; Korte, Cheryl. “Polychromed Quattrocento sculpture in Florence.” ProQuest Dissertations Publishing, 2011. https://search.proquest.com/docview/885865335?pq-origsite=summon
Locating the Materials of Italian Renaissance Sculpture 