The intervention involved the restoration of the internal façade of the Milan Cathedral characterized by an area of about 1500 square meters of Candoglia marble. The counter-façade was extremely blackened by large quantities of black smoke deposits due to the exposure of candle smoke and the presence of the main openings of the church, from which fine dust and smog present outside the building can reach the surface stone. The stone ashlars were intact, with no particular problems except punctual saline efflorescence positioned at the top of the central arch, where an infiltration affected the roof. The pink granite used for the portals appeared to have the same problems as marble, mostly related to the chromatic interference of the seals. The bases and the capitals of the columns, made of black marble, appeared graying and had some cracks.
Careful dusting of all surfaces with vacuum cleaners and brushes to remove surface deposits, extraction of soluble salts carried out with a cellulose pulp and deionized water pack until the surface is completely dry.
The statues in Candoglia marble, the windows of the upper order and the bases of the columns were cleaned with a compress of saturated solution of ammonium carbonate and cellulose pulp.
The black marble elements were cleaned with gel and then protected with microcrystalline wax applied with a brush and swab.
The chromatic balancing was performed with the aim of returning the correct reading of the whole. So we opted for a mimetic retouching of the toned seals, matching them one by one with the different shades of the ashlars and recreating the appearance of the original stylings, with subtle light lines.
The bronze letters that make up the inscriptions above the main portal have been treated with a specific cleaner for metals and the gilded patina integrated with gold in wax.