In 1629, Pope Urban VIII Barberini, commissioned Bernini to build an altar dedicated to the Blessed Sacrament, but which was completed only in 1673-1674 under Pope Clement X Altieri.
Bernini completed an altar with a tabernacle, flanked by two kneeling and adoring angels, of these two angels produced for the bronze castes, we still have one surviving model.
Materials and Implements
The materials used for these models are mainly clay combined with straw. The straw was used in the impasto in order to prevent the formation of cracks during the drying process.
This impasto, made of clay and straw, is shaped on a wrought iron structure fixed to a vertical wooden support.
In some areas, the internal structure is covered with bundles of vine branches tied with twine used to increase the thickness where necessary.
The mixture of clay was applied layer upon layer with different compositions and thicknesses. The final polished surface is the result of the spreading of a thin layer of fine clay painted with clay-water over the various strata which produce variable thicknesses.
Some documents of the time which refer to the construction of these models evidence the use of materials like bundles of sticks, hay, cart delivered clay, as well as tortori which were braids of straw or hay generally used for cleaning horses.
These materials can be easily seen in those areas where the molded surface is lost, leaving exposed the lower layers also called superfici di frattura.
Preparatory models for the bronze angels of the Chair of St. Peter
These Bernini Angels are very important works because they illustrate how a masterpiece is born, while their high quality gives evidence of Bernini’s direct intervention in their creation.
The purpose of these bronze sculptures was to guard the venerated relic of the Cathedra in wood and ivory, on which, according to medieval tradition, St. Peter sat to instruct the early Christians (however, the throne was given to Pope John VII by the Emperor Charles the Bald in 875 AD).
The Bernini models testify Bernini’s hard work on this project which lasted ten years and was modified several times over this period. The angels, in fact, have different sizes and attest two stages of work. The final Cathedra which is now visible in St. Peter’s, is more than double the original design.
In 1658-1660, a natural size model of the Cathedra was completed in wood and plaster and then placed in the apse of St. Peter to check the proportions of the whole. Right afterward the first models of the angels were placed in their position but they appeared too small to Bernini’s friend and painter Andrea Sacchi who said: “These statues should be a good hand width bigger … and Bernini who had already realized on his own that the statues were too small, decided to remake them” (L. Pascoli, Vite, 1730). With the help of sculptors Ercole Ferrata and Antonio Raggi, Bernini decided to enlarge the models, and performed a second version of the Angels used for casting in bronze.