AIC's 41st Annual Meeting

Carlo Serino, Founder, Equilibrarte; and Antonio Iaccarino Idelson, Conservation of Canvas paintings Professor, University of Urbino

This talk presents an intervention of the large painting and the counterweight machine designed to allow its movement during special celebrations, on the altar of St. Ignazio, in the church of Gesù in Rome.

The chapel and its altar are conceived as a “theater” displaying the life and sanctity of St. Ignazio, the founder of the Jesuits. It represents the triumph and glory of the apex of Roman baroque culture. Designed and executed by Andrea Pozzo in 1695-9, it is well preserved and is one of the few remaining important altar machines in Catholic Europe.

Central to the altar is a large canvas painting depicting St. Ignazio. Painted by Pozzo it measures 6.5 x 3 meters. Working as a theater curtain the painting can be lowered to reveal a monumental statue of the Saint originally made in silver, gilt bronze and precious stones. He stands in full glory, housed in the niche behind the painting.

The chapel, completely renovated when Pozzo won a competition held in 1695 for reshaping the left transept, is among the most important creations of the late baroque. It is also decorated with frescoes by Giovanni Battista Gaulli (1639-1709), marble and gilt bronze sculptures by Pierre II Le Gros (1666-1719) and J.P. Théodon (1646-1713), and the splendid bronze balustrade designed by Pozzo. An earlier gilt bronze urn by Alessandro Algardi (1595-1654) conserves the body of the Saint.

The treatment of the painting and altar mechanism had to be addressed on several levels of complexity. Though repaired on numerous occasions much of the original mechanism had survived and all of its elements were still recognizable. But it had been “lost” to use in a lowered position during the last decades. The goal was to conserve and repair as much as possible, replacing only what was necessary to bring it into working order. Most of the damage derived from natural degradation of materials, but some from problems in the original design. Therefore, a deep understanding of the original structure was crucial, as it was necessary to make some difficult decisions in order to assure future safe and efficient movement of the painting.

The original wood stretcher was conserved with some of the original metal fittings. Only those parts that were too deteriorated to assure safe use were replaced. The same has been done with the counter-weight, pulley and guide rails. Regrettably the main rails, originally in chestnut wood and steel, and the brass wheels that guided the painting through a narrow slit in the stone structure, had to be replaced. Deformation of the rails had pushed the painting against the wall causing severe tears in the canvas during decades of improper use. New stainless steel rails with runners fitted into the rails with sealed ball bearings have replaced the old rails and wheels.

The painting has been restored, relined and reattached to the original stretcher; however it is now attached only with a spring system placed on the back of the stretcher. This keeps the painting under constant elastic tension with only the minimum amount of force that was considered necessary to hold it in plane. In this case, 2.4 N/cm was the force that assured continuous planar stability of the lined painting. Teflon profiles were added to the edges of the stretcher to allow the movement of the canvas along the entire perimeter, and the painting is now free to expand and contract following environmental variations, avoiding all stress concentrations.

Working within the requirements of the modern church, the movement of the counterweight is now produced with an electric winch. A priest’s push of a button on a hand-held remote control has replaced manpower in raising and lowering the painting, and sensors located at key points assure its safety.