Stefano Della Torre1, and Lorenzo Cantini2
1) Full Professor, Dept. ABC – Architecture, Built environment, Construction engineering,
Politecnico di Milano, piazza Leonardo da Vinci 32, 20133 Milano (Italy)
e-mail: stefano.dellatorre@polimi.it
2) Contract Professor, Dept. ABC – Architecture, Built environment, Construction Engineering,
Politecnico di Milano, piazza Leonardo da Vinci 32, 20133 Milano (Italy)
e-mail: lorenzo.cantini@polimi.it

Keywords: Cathedral of Milan; historical archives, Ferrari da Passano, stone durability, special resins.

Abstract. Since the long collaboration between Veneranda Fabbrica del Duomo and Politecnico di Milano (VFD) was renewed, the Duomo Cathedral has been investigated from different points of view in order to enhance the continuous care procedures, which can be understood in the theoretical frame of preventive and planned conservation [1].
Among the different study approaches, the collaboration with the historical archive of the VFD showed the potentialities for recording the main pathologies afflicting the building during different periods and for classifying the intervention criteria set for facing specific problems affecting the main loadbearing structures and their materials.
The archive documents provided precious indications concerning the restoration works and strategical measures adopted for the common decay problems presented by the building materials [2], [3]. A turning point in the intervention philosophy, observed in the archives documents, occurred in the beginning of the 1960s, when the Cathedral was concluded, and the VFD had to move from construction and maintenance activities to the conservation issues [4]. On behalf of the large amount of interventions that became a constant care for the building, from the second half of the last century, the VFD promoted interesting efforts in the maintenance policy by experimenting new technological solutions [5]. With the aim to protect the different features of the Cathedral, new special mixtures were introduced in the common intervention criteria, experimenting on site new resins for repairing. At an impressive extension, these practices produced new systems made up of different materials, namely marble and stones, iron, mortars and resins, whose compatibility on the long run is still to be evaluated. This work focuses on the consequences observed after the development of a clear common practice for the care requested by such a complex building.