As already described in our article of 14 December 2012, Room 41 immediately seemed a particularly representative example of the numerous problems affecting the Neronian complex of the Domus.
A careful study of the structure of the vault, at a height of 12 m, showed the seriously compromised state of its constituent materials, due especially to a cut high up, caused in the Trajanic period by a sewer, and to percolation through the tree roots from the gardens above. All these factors have led to water seeping in over time, sometimes in great abundance, compromising the resistance of the materials making up the mortar.
The decorations of the vault are preserved only at the sides of the room, covering a total area of about 30 m2.
The preparatory layers have lost cohesion and are often detached from the vault structure;
we also noted the worrying presence of root systems emerging between the structure and the plaster.
The surviving paint layers present localized bio-deterioration phenomena, and extensive cohesion and adhesion defects.
The severely compromised state of conservation of the wall structure and the decorations of the vault led us to make the difficult, but necessary, decision to detach the two portions of decoration at either end of the vault in order to consolidate the wall structure more effectively whilst simultaneously ensuring the conservation of the paint layers.
With a view to starting this intervention, we therefore proceeded to carry out the necessary alterations to the scaffolding to allow us to set up the equipment needed for the detachment and to position a series of props for the vault.
Work then began with the preliminary phases of biocide treatment and the reduction of surface encrustations with dry methods. We then carried out consolidation work to repair cohesion defects with a series of spray applications of nanolime, appropriately diluted in isopropyl alcohol.
After completing consolidation operations with further applications of nanolime, at the necessary time intervals for it to set, the operation was judged to have been a success.
As the cohesion of the paint layers had been restored, we undertook some preliminary coating tests with cyclodecane and micropores and with cyclodecane and acrylic resin in solution. This was followed by the detachment phase; we decided to start from a marginal area of the decoration preserved at the southern edge of the room, the most severely compromised.
After applying an isolating layer of cyclodecane, the area to be detached was coated with cotton gauze and micropores.
The coated area was reinforced with a double net of plastic-coated metal, fortified by the insertion of a semi-rigid plastic-coated metal tube.
A counter-form was applied and the area was detached following the line of a pre-existing fracture.
The detached portion was levelled on the back before being lowered to the ground onto the platform that had been prepared in Room 40, where subsequent consolidation treatments will be carried out before it is put back in place.
The next phases will involve the application of cyclodecane over the whole decorated surface to be detached as an isolating interface and a coating of reinforcing gauze applied with acrylic resin in solution. We will then prepare the support structure needed for the detachment and for lowering the plasterwork onto the platform.
In order to determine the impact of these works on the microclimate we are recording presences on the scaffolding, the number of people and the treatments carried out on a daily basis so that we can compare these data with variations in microclimatic parameters.
The works, still underway, are being carried out by the company DART owned by Alessandro Danesi.