79 The sculpture of the crucified Christ of the quatrefoils is defined by the thin white overall paint layer and an additional blue contour (Fig. 123). The thorncrown was painted in green (Fig. 124). Pigment analysis revealed a palette of pigments used in different quantities and mixtures to obtain different hues: lead white, minium, red lake, copper green, azurite60, ochre, umbra. The binding medium contains oil.61 Particular attention was paid to the analysis of the blue pigment, as the colour of the blue did not appear to be typical of azurite. However, the detection of azurite was confirmed by a powder diffraction analysis. The presence of calcium oxalate detected in the pigment analysis and the particular colour of the azurite could well be pigment variants attributable to the Mexican origin of the material. Fig. 124: Thorncrown with traces of original green colour
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