during a study and conservation project in 2002–03, scientists at the getty conservation institute examined the photograph using x-ray fluorescence spectroscopy, reflectance fourier transform infrared spectroscopy, and other techniques. they confirmed that the image consists of bitumen and that the metal plate is pewter (tin alloyed with lead, as well as trace amounts of iron, copper, and nickel). the institute also designed and built the elaborate display case system that now houses the artifact in a continuously monitored, stabilized, oxygen-free environment.