The cleaning process is a very delicate phase of the conservation work. In fact, it is an irreversible activity, which, if not carefully calibrated, can cause irreparable damages to the monument to be restored. Therefore, it is not possible to work with standard techniques, as every monument is a unique case on which it is necessary to calibrate the intervention mode specifically.
This awareness is the root of the cleaning method proposed by IBIX; the structure of the equipment, their functions and adjustments, are specially designed to ensure the greatest control over the process, preserving the quality of the result.
Effectiveness and potential damages are the two parameters that lead the cleaning result. The effects of the cleaning should therefore be evaluated considering the future outlook, in order to monitor the cleaning effects in the long term.
The cleaning of Trevi fountain, carried out partially with IBIX technologies, is an excellent example for the intervention process described above. The importance of the monument - which is perhaps one of the most famous architectural works in the world - requires the utmost care in defining the operating mode and it is an outstanding test for the cleaning level guaranteed by IBIX equipment.
Describing the stages of the fountain cleaning (those concerning the use of IBIX technologies) is therefore a great way to explain the IBIX method. The intervention project consists of three phases: materials analysis, cleaning tests, results analysis. The correct execution of the sequence leads to the best cleaning process, which will be developed in the specific case of intervention.
The cleaning of the fountain was carried out in order to remove the thick deposits of limestone - which had been uplifting over the years - ensuring the utmost respect of the underlying marbles.
Through various samplings, it is possible to define accurately the layer of material on which stopping the abrasion. The work is carried out at low pressure, starting from 0.2 bar. On the Trevi Fountain, the equipment were used in the dry mode (without water). The material selected for the intervention was the almandite exrafine 200 mesh. It consists of sub-angular shaped grains of mineral stone: it is an all-natural, chemically inert mineral abrasive containing no toxic metals, silica, ferrite and/or carcinogenic substances. It is a very tough and effective material, but at the same time it allows an optimum selectivity of the cleaning process and enables to use very low operating pressure values.
The media cleaning operations were performed with the HELIX gun, which is another important parameter of intervention. The Patented HELIX® system consists in a special operating gun equipped with an original helical vortex nozzle design: this guarantees not only the maximum protection of the valuable surface patinas and historic coatings of precious artefacts, but also optimum worksite performance. This system exploits a combination of the Venturi effect, generated by the special conformation of the outlet cone, with a device that induces a helical rotary movement, in order to reduce considerably the air capacity required to operate the machine. The wider tangential contact area generated by any same working pressure guarantees up to 30% more in productivity.
HELIX is a tool created specifically for the IBIX intervention project. Its particular features perfectly fit with the scientific approach described above.
The application gun increases the distance of the operator from the surface minimizing invasiveness without losing the evenness and effectiveness of the cleaning and avoiding that the operator needs to make constant corrections, which can result in the definitive loss of the layers to be conserved.
Thanks to the IBIX technologies, it has been possible, in the case of the Trevi Fountain as in other important historical and architectural contexts, to satisfy completely the project requirements.
The results achieved thanks to the conservators’ know-how and to the IBIX technologies have now come back to the public view: the restored Trevi fountain was inaugurated last November.
[by Caterina Giovannini]
Lazzarini L., Laurenzi Tabasso M. , Il restauro della pietra, Utet 2010.
Alessandrini G., Feltrami C., Cordaro M., Torraca G., Patine, pellicole e patinature, in Diagnosi e progetto per la conservazione dei materiali dell’architettura, De Luca Editore, 1998, Roma.
UNI Beni Culturali, Materiali lapidei naturali ed artificiali. Descrizione della forma di alterazione - Termini e definizioni, UNI Standard 11182:2006.