*4.2. Comparison with Other Works*

There are few diagnostic works in which the hierarchy of colourants is discussed from the analytical point of view. Clark [9] cited the medieval practice of using the most valuable colourants, with particular reference to blue pigments, for the most important subjects inside a painting, but gave no specific information on the items analysed.

Bruni et al. [39] studied the decoration of a 15th century parchment folio kept at Archivio di Stato in Milan, originally commissioned by Francesco Sforza. The work is attributed to the Italian artist Michelino dei Molinari. The hierarchy of the colourants used by the artist was similar to that used by Antoine de Lonhy in the case of red pigments: the Child's vest, the tongue of a green dragon and the red initial capital letters in the text were painted with vermilion, whereas a red flower below the dragons was obtained by a mixture of red lead and vermilion. However, it was different in the case of blue pigments, since ultramarine blue and azurite were used separately for features with different symbolic value: the former was used for the mantle of the Virgin Mary and the Sforza's *Biscione* (the symbol of the Sforza dynasty), while the latter was used only for the initial capital letters in the text.

On the other hand, Bersani et al. [40], in a study on the ms. Pal. 212 (Biblioteca Palatina in Parma, Italy), a *Book of Hours* with 14th century miniatures produced in Bruxelles, found an unusual hierarchy of blue pigments, with azurite used in the central painting to realise the mantle of the Virgin Mary, one of the most important subjects of all illuminated books and lazurite used for the decoration of the frame, a feature undoubtedly less important. The authors attributed this unusual choice to the unavailability of lazurite for the artist who decorated the central painting. In the end, therefore, the choices of the artists follow their decorative schemes, but they are related to the availability of materials.

Of course, the hierarchical use of colourants can be found in other types of paintings. In the study by Edwards et al. [41] on the wall paintings of the Church of SS Cosmo and Damian in Basconcillos del Tozo (Castille y Léon, Spain), the authors highlighted the selective use of the precious cinnabar for the most important biblical figures.
