Stiacciato

Donatello's schiacciato work Herod's Banquet, Siena Baptistery.

Stiacciato is a technique which allows a sculptor to create a recessed or relief sculpture with carving only millimetres deep and mere scribing. To give the illusion of greater depth, the thickness gradually decreases from the foreground to the background. In some ways it is more similar to a 2D image than a 3D sculpture and so the relief can use perspective. Vasari writes of the technique:

The third types are called bas- and stiacciati-relief, which have nothing in them but drawing the figure with dents and schiacciato relief. They are very difficult if there is a large amount of drawing and invention involved, because it is hard to give these things grace thanks to the mode's love of contours. And Donato [ie Donatello] worked best of all sculptors in this genre, with art, drawing and invention. We see many of this kind [of sculpture in the form of] highly-figured ancient Aretine vases, masks and other ancient works; and similarly in ancient cameos and in bronze-stamping cones for medals and coins.

The technique was mainly used in the 15th and 16th centuries, begun and dominated by Donatello. The earliest surviving example is his St George Freeing the Princess (1416-1417) and his other works in the genre include the Pazzi Madonna (1430), The Assumption of the Virgin (Sant'Angelo a Nilo, Naples, 1426-1428) and the background of Herod's Banquet (Siena Baptistery, 1423-1427), along with The Virgin and Child (1426) by his studio.