DESIGN THE RECONSTRUCTION OF VENERANDA FABBRICA DEL DUOMO DI MILANO. HISTORIC BUILDING RESTORATION OF THE SPIRE GUGLIOTTO AMADEO Cores4n

Anne Shari Napoli

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anneshari.napoli@cores4n.com www.cores4n.com

Veneranda Fabbrica del Duomo di Milano. Restoration of the spire Gugliotto Amadeo

The “Gugliotto Amadeo” (Amadeo Spire), built (1507 – 1518) during the Sforza period by the architect Giovanni Antonio Amadeo is in correspondence of the “Guglia del tiburio”, one of the pylons of the lantern that supports the “Guglia Maggiore” (Greater Spire). The spikes were born as counterforts but over the years they were transformed and got enriched by many decorations, especially statues. The “Gugliotto Amadeo” in particular, executed in the greater part in Candoglia marble, shows many decorations and geometrical patterns in Verona red marble and slate and has a passage that links it directly to the lantern. Its state of conservation was mediocre: the typical colour of the Candoglia marble was completely covered by a layer of dark substances caused by the deposit of particulate and pollution and has been influenced by the exposure to atmospheric agents. Especially in correspondence with the ornaments, the statues, the pinnacles and the projecting decora tions the spire has been affected by cracks. This led to a total or partial loss of the volumetric plasticity of the artefacts. The remaining part of the deterioration encountered is to be assigned to the aging of pre vious interventions dated back to the 60’s: in fact, the mortar used to fill the joints of the marble blocks appeared yellowed and detached from its support.

The whole restoration intervention was realised with the collaboration of the craftsmen of the Veneranda Fabbrica del Duomo di Milano. In general, the main restoration operations performed were pre-consolidation, cleaning, biocide treat ment, consolidation, grouting and they affected the whole Gugliotto. The last part of the intervention is still in the making and consists in the final protection of the marble surfaces. Before starting with the cleaning operations, a superficial pre-consolidation has been made; it made the protection of the decorated architectural surfaces pos sible, which had been weakened by the pollution. Otherwise these surfaces would have been majorly affected by the mechanical cleaning. After the pre-consolidation there was the cleaning phase, one of the most chal lenging of the entire intervention: its goal was to remove the layer of polluted substances without negatively affecting the structural and volumetrically integ rity of the marble. To avoid the decohesion of the marble another consolidation was done through nanosilica particles. At the end of this preparatory phase a biocide treatment was carried out. Once those interventions were concluded, it was necessary to reintegrate the concrete joints of the marble blocks previously left below the level by the Duomo craftsmen. In the meanwhile a different treatment was studied and designed for the grouting of the marble block joints which were replaced with new ones. Due to the fact that the restoration process is still ongoing, at the moment we can only preview the final results of the intervention: we are now proceeding with the final protection of the marbles and, after that, the “Gugliotto Amadeo” will be ready to get back to its original splendour.