Congresso congiunto SGI-SIMP 2018 - Geosciences for the environment, natural hazards and cultural heritage

Abstract

A brief introduction will define what Cultural heritage is from the Conservation Science point of view and will explain how the scenario changed with the advent of different materials in contemporary art. Goals of the study (archaeometry and conservation). Impact of rapid technological advances resulting in a flourishing of new instrumentation. Use of large facilities (synchrotron and neutron sources) compared to the proliferation of small portable noninvasive instruments. Composition of the Na-pyroxenes in green stone axes by a noninvasive XRD technique to determine the stone provenance, used for elucidating the trades in Neolithic Europe. Texture of the copper axe of Similaum man shed light to the metallurgy of Eneolithic period. For large facilities: Structure refinement of Maya Blue and identification of indigo in the palygorskite grooves. Use of neutrons for CT-scan of large statues (Robert van Lange), compared to powerful X-ray sources and medical equipment (Casali, Getty). For portable instruments: Ubiquitous use of hand held XRF. Advantages and disadvantages. Portable Raman, FTIR, XRF/XRD noninvasive techniques. Some examples of non-conventional applications of portable XRD. Michelangelo Last Judgment censure panels in the Sistine chapel: problem of dating the interventions with the goal of removing the most recent ones only. XRD proved to be the solution since the three painters used different yellow pigments. Discoloration of the blue sky painted with Lapis Lazuli. It was proved to be a rough partial cleaning performed using ash. Imaging has become very important: Multispectral Imaging, involving different filters and light sources from UV to IR, helps mapping the various substances on the surface. VIL, Visible Induced Luminescence, allows to take pictures of Egyptian blue only. Examples from Roman-Egyptian funerary paintings (Fayum), Herculaneum and X century Lombard church. Reflectance Texture Imaging, combines many pictures taken at different illumination angles, and allows for changing the light direction on the computer at a touch of the mouse. When X-ray Radiography in transmission is not practical, it can be substituted by Electron Emission, which involves the first 50 micrometers of surface only. SmART_scan: a program that simulates XRF scanners, without the expensive equipment.