The restoration of the south and north walls, organized by the IVBC as part of the three-year training course for ‘Restorers Collaborators”, was realized, in cooperation and under the technical direction of the restorers and teachers, by students of the second academic year during the period between February 2005 and November 2006.
The south and north walls were painted, fresco technique representing allegorical figures and an architectural perspective with mirrors and candelabra, by Jacopo Guarana and Gerolamo Mengozzi Colonna and Agostino around 1766. In the middle of the north wall is painted one of the seven gifts of the Holy Spirit, the Consilum, faced the opposite wall by Prudentia. To the right and left of the figures there are two double windows on the north, and fake windows on the south, moldings and Istrian stone.
The phases of the introduction project had the following steps:
a) identification of the artistic techniques used by a direct observation of the artifact, diffused light and grazing, which highlighted the “giornate”, traces of dust and succession of layers of plaster;
b) the preservation status map;
c) diagnostic laboratory;
d) photographic documentation;
e) cleaning tests.
The painting showed a widespread degradation and different conservation conditions. In both walls, the presence of large repainting and a lot of abrasion was noted. In addition to the presence of a white layer (gypsum) superimposed on the original surface, reached the millimeter thick in some area, was observed a protective and / or fixative film. The orientation of the north wall means, because of his exposure to atmospheric events (rain, wind and temperature changes) and the outside plaster’s wall falling down leaving the brick exposed, an increased degradation. The bad status of the four windows of the wall are also a source of many rainwater’s infiltration.
A series of laboratory investigations has been devoted to the knowledge of the composition materials and the identification of degradation products. The artistic technique was identified with bright stratigraphic sections. Salt efflorescence samples were collected for identification and quantification by petrographic thin sections, stratigraphic polished sections and analysis in ion chromatography. The presence of a protective substances or in any case, a surface treatments, has been investigated by spectrophotometry and stratigraphic glossy section infrared Fourier transform (FT-IR).
The restoration work was structure by the following phases:
The cleaning phase was aimed to remove the foreign superficial film composed by vinyl resin, polyvinyl acetate.
Removing polyvinyl acetate
Removing chalky layer surface
b) pre-consolidation and consolidation plaster detachments
c) Removal and replacement fillings and gaps
d) Pictorial retouches
The 2007 saw the conclusion of the restoration of the Ducal Chapel, by the intervention on the ceiling and the eastern and the western walls, performed by three-year training students for Collaborator-Restorer of Cultural Heritage.
The ceiling is a work of great interest for its compositional complexity and sophistication. The middle figurative representation was painted by Jacopo Guarana in 1766 and an illusory architectural frame made by James and Gerolamo Mengozzi Colonna. The central part represents the triumph of Venice, represented by a female figure on a throne, surrounded by allegorical figures such as Commerce, Navigation and Agriculture; groups of angels and cherubs overlook the figures. The figurative part of the ceiling is surrounded by an fake architectural frame that mimics a wood paneled ceiling, with its gilding, and fake stucco reliefs.
The artistic technique is the fresco and “mezzo-fresco”, excluding some few parts realized “a secco” to correct the setting of some “giornate”, on two layers of plaster applied over the wood “cantinelle” support. The middle part of the ceiling, between the central compartment and the frame in fake stucco, has a gilding decoration made of numerous small brush strokes. Latter artistic technique, after a laboratory analysis, was found to be “a conchiglia”, a very thin gold powder applied by brush on a natural resin layer.
The eastern and western walls complete the architectural decoration of the room. On one side, there is the prodigious altar of Jacopo Sansovino, two windows and two doors, one of which allowed the Doge to reach the apartments below. On the other side, a small portal with openings on the next room called “antichiesetta”.
The conservation status of the painting could be considered good from a structural standpoint. The esthetic presentation of the art work was affected by a general colour darkening, not only due to a deposit of dust and fat, but also to a past egg and oil treatment. The northern area, about a meter square dimension, was caracterize by salts efflorescence caused by an old water infiltration from the roof. Small but frequent uprisings of the plaster were present over the nails, holding the”cantinelle” anchored to the beams of the ceiling.
The gold was intact almost everywhere, except for the efflorescence area where the falling gold left a visible blackish preparation.
In the central part of the ceiling, in the Guarana’s figure, were visible lost coloration of the flesh tones of some figures.
The walls facing east and west of the Chapel presented different conservation problematics from those on the ceiling. At west, considerable infiltrations of water, due to the presence of two windows, has produced a consequent loss of pictorial film. In the north-west area, in the top part, the surface appeared scraped and with large retouches gaps and fillings. On almost entire surface were find a thin whitewash, also found on the north and south walls.
In the east wall placed no important decay phenomenon has been founding. A major renovation, probably from the nineteenth century, recover almost half of the area and is related to a structure modification of the entire wall.
The IVBC’s internship began on January 16, 2007 by the realization of a graphic documentation of the ceiling and side walls and a subsequent mapping of its degradation.
We proceeded then to the cleaning tests to define a correct working methodology, setting times and solution’s concentration to be used. At the same time, laboratory analysis has been made.
First of all, we protected the flaking area with Japanese areas to fix and consolidate, then, those parts.
At this point, we started the cleaning, beginning by treating the surface with ammonium carbonate compress.
As regards the area of fake coffered ceiling, with a high numerous gilding, was necessary before applying a protective wraps. The Cyclododecane, aliphatic hydrocarbon which after application, sublimes without residue, has been perfect for our purpose.
The compress with ammonium carbonate has allowed to remove, in addition to deposits of dust, the “mash” that burdened the painting in shades, making the color loading and deaf , thus depriving the ceiling of his brightness and depth.
The efflorescence presents in one area has been removed with a soft brush before cleaning with compress extraction.
Following the removal of the old fillings and the new on done, we did an integration painting with watercolors.
Due to the location of the work it was not considered appropriate to give any kind of final protective surface.
Est and west walls
The west wall has been treated with the same cleaning method of the ceiling following by a treatment with ion exchange resin where was present the thin layer of gypsum, recovered in the north and south walls too. The stone elements, window frames made of Istrian stone, were cleaned with Ammonium carbonate on Japanese paper.
In the intervention on the east wall, after cleaning with a similar methodology to the opposite wall, we took a reflection moment to front the “remade” area. It has been decided, in agreement with Rapresentative of the Cultural Heritage Ministry, to keep it. It was therefore sought to integrate it in the better way with the rest of the wall.