Color Restoration of Heritage: restoration of tone colors and finishes of the historic tuff architecture. The case of San Domenico in Bari

On the edge of the old city of Bari, after the spanish domination were created, instead of the medioeval walls, a row of monastery. Between them there was the Dominicans’ convent. In the nineteenth century, after the national unification, this one passed in the public property as police department. with great demolition and reconstruction (mostly on the side of the modern city). It was saved the baroque church of “San Domenico” that occupied the North-West corner of the complex, facing the old city on the sight of the castle fifteenth century entrance. The church is now lead by the Confraternity of the Blessed Virgin Mary of the Rosary and is now completely unapproachable from the near building, on the East and South side even if it was once its own monastery. The condition of rising groundwater of the historical center and some specific condition of the building led to an important state of decay on the west wall of the church that face on a very narrow street. Now the Confraternity decided to restore the church, the first part of the work (just concluded) have to be started from the most critical area: the external face of this wall. At the moment of the work the lower part of the facade was covered by a encrustation of concrete-plaster, and the most of the upper surface, in square blocks of tuff, was very deteriorated by black crust and joints filled in concrete mortar, over a very diffuse state of tartar, alveolization and erosion of the stone surface. The operation of restoration started with the research of the original condition, first trough the archive documentation, and immediately after on the monument itself. Unfortunately the large amount of work that the church has undergone erased many traces In this condition we tried to preserve all the surviving traces and rebuild the lost image of the church so all the phases of the work were conducted like in antiquity. The mortar was constitued in place in calck mixed whith grinded tuff and pozzolan to have the correct base for the further finishing intervention. We cared to the chromatic balance of the mortar within the tuff blocks because of their continuous variation, in order to preserve a material and chromatic homogeneity of the façade , even when, over the time, the protective layers will be disaggregated and missing. After this phase, different solutions have been proposed for a kind of bland-plaster (“scialbo”) more or less greasy in order to find the right balance between the issue of the protection of the materials and the preservation of the historical image of the church that in the popular sight have lost the plaster. In the opinion of the authors, in this case, it was possible to oppose the fashion of the "stone face view" dangerous for the conservation return for a finish that is testimony of his time, faithful in material and function