New perspectives on colours in medieval Umbrian architecture

Romanesque and Gothic architecture was polychrome and - in most cases - the appearance of medieval cities had to be much more 'colourful' than it looks today. From 20th century, in Umbria, high seismic risk has strongly shifted the attention on structural aspects of buildings to the detriment of formal authenticity of historical construction elements causing serious losses of material of high documentary value, especially regarding mural finishes, which are the most vulnerable part of the architectural apparatus. Present study deals with the problem of colour in the medieval Umbrian wall facings in order to deepen the history of architecture to increase awareness in conservation and greater the enhancement by also offering ideas for possible reconstructions of the decorations. The aim is to investigate conservation and restoration issues of architectural surfaces, focusing on the value of the authenticity of matter. Recent studies on the use of bi-chromatic decoration in medieval building techniques in Umbria and on the chromatic alteration of local stone have drawn attention to new research perspectives about the exterior layers of architectural surfaces and on the characteristics of their pigmentations. It has been demonstrate that some types of stone such as the Scaglia Rossa - well known as the 'pink stone of Assisi' - can change colour in a non-reversible way from red to yellow (this variation is perceived by the human eye as a passage from dark pink to light pink and/or to white) in relation to weather phenomena. Based on these considerations, the still visible traces of possible chromatic transformations of this building material and of historical finishes (e.g. painted plaster) were examined, especially where they were used in bi-chromatic patterns (white-rose). Differences between shades of colour of the stone according to the exposure to sunlight and rainfall in relation to its position on the structures have been observed, highlighting the importance of a reinterpretation of Middle Ages Umbrian architectural surfaces. In particular, it is possible that the decoration obtained with the juxtaposition of pink and white limestone elements, typical of the villages of the Umbrian-Marche Apennines, could have been characterized by much more vibrant colours, with contrasts similar to those obtained in the decorations of the contemporary Tuscan buildings. This theory is also validated by the comparison with interior pictorial decorations and with the painted architecture of some of the greatest coeval artists.