The polyptych became part of the collection of the Savoy Gallery at the beginning of the last century and depicts the Christ of Pietà crowned with thorns flanked by a pair of cherubs in high relief. In the register below is the Madonna seated with the baby in her lap. The work was never subjected to conservative interventions.
WOODEN TRYPTYC SCULPTED IN THE CENTRAL PART, PIEDMONTESE SCULPTOR, XVI CENTURY
THE PROBLEMS OF RESTORATION
From diagnostic investigations, the presence of many repainting layers on an original underlying gilding was found in some areas. The traditional cleaning methods, both chemical and mechanical, were not satisfactory in removing the repaintings as the final layers were still tenaciously adhered to the surface of the gold leaf. It was therefore decided to carry out removal tests of the different color samples in order to evaluate the effectiveness of the laser technique on the different stratigraphies of materials and evaluate their non-interference with the underlying gilding.
The most suitable laser instrumentation for this work was an EOS 1000 LQS system with different operating parameters depending on the different types of stratigraphy. In some cases it was necessary to proceed at frequencies of 1Hz, sometimes surface wetting with ethyl alcohol was necessary. The cleaning allowed to highlight the external gilding while the presence of the first and most ancient gold foil on the Armenian bole was documented only in limited areas of the surface of the work. The removal of the repainting by laser has not interfered with the stability and the state of conservation of the work already quite critical reducing considerably the risks related to the use of solvents and those induced by stress due to mechanical removal.
Conservative and responsible body for restoration: Venaria Reale Conservation and Restoration Center, Turin