Diagnosis

Each time the restoration of a monument is undertaken (from an individual piece of art to an entire facade of a building) it is fundamental to obtain a series of data that allow the planners to ensure that the restoration project is as accurate as possible. For this purpose it is necessary to create a study group that includes a diverse range of expertise: humanist, scientific and technical, that should be coordinated by a director (either an architect or an expert in the history of art).

Phases of the diagnostic studies

1.The creation of an architectural relief

It is necessary to carry out an architectural relief of the monument, or a referenced photographic plan, or both, or preferably, to acquire data (including digital images) with a laser scanner, with the aim of creating a base upon which to register the consequent investigations. This can be done either on paper or digitally.

2.Historical–archival research

Historical–archival research can contribute significantly to the restoration team’s knowledge about the events that have taken place during construction and maintenance of the monument since its creation; this principle is of equal value regarding the most ancient works or recent interventions. The data obtained in this phase is of fundamental importance for the formulation of consequent scientific investigations.

1. Phenomenological macroscopic observations

The direct observations, carried out using a trabattello, a mobile crane arm or a specific diagnostic observation structure, are designed to obtain an initial visual characterization of the materials and the conditions of their surfaces. Observations are carried out on the spatial distributions of the materials, of the surface formations, the type of degradation, the traces of previous work on the surfaces etc. This is done in order to allow (with constant reference to the data obtained from the previous phase) the identification of various construction phases and the formulation of hypotheses regarding the presence of the phenomena of current degradation or previous degradation. In this phase sectors are established for the collection of samples. When problems of a structural nature are identified, it may be necessary to consult an engineer.

2. The collection of Samples

The aim of this phase is to collect samples in order to analyse the characteristics of the materials, the typology of degradation and to identify the surface formations. The sampling is carried out using small scalpels to remove minute fragments (the smallest dimensions being 1mmq) and dust. It is also necessary to produce detailed documentation for each sample taken: once signed, these are accompanied by a description of the reason for the selection of that particular sample and its precise location in addition to photographs made of the area from which the sample is removed both before and after its removal.

3. Laboratory Analysis

Biological, chemical, mineralogical and spectrographic analyses are carried out (see the project table of the restoration of the Duomo) in order to establish the character of the stone based materials in the original piece, the typology of their alteration and the surface formations present. The laboratory analysis, with particular reference to microscope analysis of thin and ultra-thin sections, allows the researchers to distinguish between the residue caused by pollution and that remaining from substances applied onto the surface for aesthetic purposes.

6. ‘Mapping’ the materials and the state of conservation

The next step is the verification ‘in situ’ of the correspondence between the data from the laboratory with the macroscopic examination of the materials and the typologies of degradation. The data is then reported onto a detailed and fully referenced photograph of the piece/ monument. The nomenclature used for the typology of degradation is in line with the norms UNI 11182:2006. The data collected is then elaborated using a GIS or a similar IT system.

7. Cleaning trials, consolidation and protection

Trials into the different techniques and products to be used for the cleaning, the consolidation and the protection of the surfaces are then carried out. The results of the analysis are examined in detail in the laboratory. Utmost attention must be placed on the selection of techniques and products to be employed for the cleaning process: the nature of this operation is irreversible; there is a risk of removing pieces of the object that we are working to conserve.

8. Computerized calculation of the estimated cost

Once the techniques and products to be employed have been established for the restoration of the various materials that have undergone different typologies of degradation, the total cost of the intervention is then calculated using IT software.