STATE OF PRESERVATION
The walls of the monumental staircase (walls, stucco, architectural stone elements, sculptures and ceilings) were carefully analyzed during the planning phase of the restoration. Stratigraphic tests revealed two layers of repainting on the original surface, of which the outermost (the visible and most recent one) presented a non-uniform grainy texture.
Removal of the overlying layers uncovered ancient fractures that were previously not visible or only partially visible. Some material losses were detected on the most protruding parts of the stuccoes, revealing under the mortar the supporting metal structure inside the figures.
The evident fracture on the dome, even after the removal of the layers of paint, was very solid to the structure. There were several stains of chromatic alteration which occurred as a result of old infiltrations. The moldings of the mirrors and the capitals were in a good state of preservation and on the whole the material losses are well contained.
The wall decoration, present in the false doors on the left side of the stairwell, presented a thin deposit of dust and incoherent dirt, which partly hid a thick repainting.
The cleaning intervention also involved the white marble sculpture representing Pope Clement XII, born Lorenzo Corsini. This was carved by Carlo Monaldi, a sculptor from Rome between the end of the 17th and the beginning of the 18th century.
The removal of the scialbo (i.e. the overlapping layers of paint) was carried out from the bottom upwards, by means of the mechanical action of a scalpel. As revealed by the visual analysis, the original layer shows a very finished surface, smooth and treated externally with a thin layer of wax, which allowed an easy detachment of the scialbo. Most likely due to their location, the removal of the colors in the upper part of the decorative stucco system was easier than that of the lower part.
The careful superficial finishing, more accurate of the stuccoes in relief of the putti, coats of arms and festoons, allowed greater ease of the removal of the layers of repainting, bringing the material back to its original layer and also in some areas allowing the preservation of the slightly amber tone, conferred by the presence of natural wax applied as a final finish at the end of the realization of the artifacts. The work on the wall paintings was carried out according to a precise timetable:
- Preparation and painting of windows
- Plastering and integration of stucco and flat parts
- Color lime plastering
- Color matching with lime glaze
- Soap protection
- Removal of surface deposits on stucco and flat surfaces
- Stucco cleaning
- Thinning/cleaning of glazes on flat surfaces
- Pre-consolidation and material consolidation of stucco and flat surfaces