Examination Report: The Polychromy of the Arch of Titus Menorah Relief

Abstract Between June 5 and 7, 2012, the menorah relief of the Arch of Titus in Rome was subjected to UV-VIS spectrometry analysis by the Arch of Titus Digital Restoration Project. This technical report details the methods by which UV-VIS-spectrometry of the menorah relief revealed traces of yellow ochre as a paint layer applied directly to the stone surface of a menorah arm and the front of the menorah base. UV-VIS spectrometry is a non-destructive technique used to identify colorants. The surface to be examined is briefly illuminated by white light. From the reflected light this produces, the portion of white light that has been absorbed by the surface is calculated. The absorbed spectra are then compared with those in a special data library comprising about six thousand spectra of different art objects. Analysis of this data, and the characteristics of the spectra, show that the yellow pigment must have been cleaned and prepared thoroughly before use, and that it was applied as a first coat. Together this suggests that the menorah was originally painted yellow.