Cleaning

Cleaning was performed in various phases. Preliminary cleaning was carried out on all the fragments. Mechanical cleaning and chemical cleaning were performed subsequently, depending on the type of material and dirt to be removed.
Preliminary cleaning removed all the gross incoherent deposits (dust, cobwebs, sand) by using a soft brush, while checking the consistence of the dirt. Subsequently, incoherent earthly deposits were eliminated with a solution of water and Desogen (5%).
Mechanical cleaning was carried out after preliminary cleaning by means of scalpels and micro pneumatic hammer. During this phase, earthly strata and biological remains were removed while testing the coherence and thickness of the earthly incrustations. Mechanical cleaning was repeated after chemical cleaning as a finishing treatment.
Chemical cleaning was performed on groups of fragments with the same deterioration on the same material that showed an identical type of decoration. It allowed a homogeneous cleaning of all fragments, independently from their dimensions. The restorers paid great attention to the application procedure and its length. The surface was first moisturized with a watery solution of ammonium bicarbonate (25gr/lt in demineralized water). Then, the restorers applied a sheet of Japanese paper on which they placed a compress of celluloid fiber and micronized silica (3:1 in volume proportion). It contained the same solution of ammonium bicarbonate used during moisturizing. Then, the compress was covered by plastic film and left acting for 20 minutes. After this period of time, the compress was removed and the surface was cleaned by rotating a soft brush, and subsequently with a hard brush and a scalpel. This operation removed all the calcium carbonate residues, which had made insoluble the earthly deposits on the surface.
This procedure was applied on all the marble and plaster fragments showing calcium carbonate incrustations. The application time was slightly increased on the stone finds.
The plaster fragments did not show detachment of the pigments. Thus they were cleaned following the same procedure of chemical cleaning as the stone finds. The pigments were of the common type used during the Roman period, including: red and yellow based on iron minerals, Egyptian blue (calcium copper silicate), and carbon black.