Differences in palette
The Betrayal and Arrest of Christ is the only one of the three miniatures to contain an arsenic-sulphide pigment, used in the dark yellow folds of Judas’ robe and in Christ’s hair, as well as pure azurite, identified in St Peter’s blue drapery. In the other two miniatures, the yellow areas contain lead-tin yellow and the dominant blue is ultramarine, often mixed with small amounts of azurite, while pure azurite is found only in border details.
St Peter’s reddish-pink robe was painted with an earth pigment, possibly mixed with small amounts of an organic red. The lighter pink robe of the apostle facing the Virgin in the Pentecost scene does not contain a red earth. This difference may reflect the desire to vary the pink hues.
An organic red was also mixed with azurite to paint Christ’s purple drapery, yielding a hue not found in the two other miniatures.