The three-tone system in Sant Climent de Taüll wall paintings: An imprint of medieval treatises

A groundbreaking analysis of the wall paintings in Sant Climent de Taüll, a UNESCO-listed Catalan Romanesque church, reveals the meticulous use of the three-tone system—a defining technique of Romanesque art. The study identified up to eight pigments mixed with precision, matching medieval treatises like Theophilus’ De diversis Artibus and Hermeneia, which specified colors such as 'membrana' (mid-tone), 'rosa,' 'posc' (darker), and 'lumen' (lighter). Advanced microanalytical techniques, including synchrotron-based X-ray diffraction and scanning electron microscopy, uncovered the layered application of pigments: inner layers on wet lime mortar, typical of fresco, while surface layers for contours were applied al secco. This finding bridges medieval art theory with practical execution, offering a rare glimpse into Romanesque artistic practices.

Oriols, N., Salvadó, N., Pradell, T., Jiménez, N., Juanhuix, J., & Butí, S. (2023). The three-tone system in Sant Climent de Taüll wall paintings: An imprint of medieval treatises. Journal of Cultural Heritage, 62, 114–123. https://doi.org/10.1016/j.culher.2023.05.021