Egg yolk is present in areas painted with red lead, and probably also with vermilion, in the two initials painted by Don Silvestro dei Gherarducci (see Artists).
The image of St Laurence also contains small amounts of egg yolk in orange and red areas, but the same binder was also employed in the initial and border ornament, irrespective of the pigments used. In all three cases, the spectral signature which identifies the binder is not as intense as would be expected if egg yolk had been used alone. It is possible that whole egg was used, or else that a small amount of egg yolk was added to another type of binder, perhaps to improve the handling properties of the paint.
The spectral signature is stronger in the fourth initial, where only the figure of Christ was painted with egg yolk. Egg yolk was not used in the initial and its ornamentation. This paradigm is consistent with the results of technical analyses carried out on other contemporary books from the Santa Maria degli Angeli set and on the Acciaiuoli Missal (MS 30). These are all linked to the work of the later generation of Florentine artists led by the celebrated panel painter and illuminator Lorenzo Monaco.
