Pigment layers and precious metal sheets by energy-dispersive x-ray fluorescence analysis

A portable energy-dispersive x-ray fluorescence (EDXRF) equipment was used to measure pigments and precious metal composition. From the x-ray spectra it was also possible to assign each pigment to the correct pigment layer, and in the case of metal sheets (e.g. gildings) to identify the correct layer distribution. Several methods have also been developed to determine the thickness of pigment layers and metal sheets. They were specifically applied to measure gold thickness in Giotto's halos in the Chapel of the Scrovegni in Padua, and in gilded copper objects from the Royal Tombs of Sipán and from the Museum of Sicán.