Giacomo Chiari

Abstract

This lecture will begin by providing a definition of Cultural Heritage from the perspective of Conservation Science, considering the radical challenge that the advent of new materials in contemporary art has posed for the field of conservation. This lecture will showcase a series of methods applied in the field of conservation science. Examples presented will be: the structure of Maya Blue, the paintings of Tutankhamen’s tomb, Michelangelo censure panels in the Sistine chapel, a hidden face under a Rembrandt painting and the mapping of Egyptian blue in medieval churches. New procedures contributing to conservation science in the areas of archaeometry and conservation are presented below.

  • Use of X-ray CT-scan for large bronze statues
  • XRF scanners: A new very powerful tool for mapping the composition of painting
  • A new program (SmARTscan) making use of hand held XRF, portable XRD and Raman to simulate the results of the XRF-scanners
  • New noninvasive portable XRD/ XRF: this technique differs from the usual X-ray diffraction by analyzing the whole object rather than just the material
  • Revisiting old techniques: Electron Emission for the characterization of thin layers of paintings independently from the substrate
  • PiRM, Pictorial remanent magnetization: a promising way of dating mural paintings based on the orientation of hematite particles. Being too invasive had to be abandoned
  • Laser Speckle Interferometry: a new noninvasive method to detect loose dangerous fragments of plaster
  • Development of imaging techniques: VIL, Visible Induced Luminescence to map Egyptian blue in paintings

CV

Academic career: 1967-2003 University of Turin, lastly as Full Professor.

During this period, he worked as a crystallographer, specializing in both single crystal and powder X-ray diffractometry. In this field, he produced more than 60 publications in national and international magazines.

At the same time, he engaged in research and practical activities concerning the safeguard of cultural heritage. More than 70 papers were published in this field.

Field experience has included several consulting projects (mostly for UNESCO, but also for the Italian Ministry of Foreign Affairs, the National Geographic Society and the Ford Foundation, beside private firms) in Iraq, Turkey, Peru, Thailand, Saudi Arabia, Ecuador, Tajikistan, Cyprus, Spain, France, Cuba, England and obviously Italy.

Major achievements include:

  • The formation of many students through all the courses (university and international) that Giacomo held in his life. The teaching and the direct interaction with students and colleagues has always been a high priority in Giacomo’s activity.
  • Bridging the gap between the highly technically sophisticated discipline of x-ray crystallography and the domain of cultural heritage conservation.
  • Introducing ethyl silicate in the field of adobe conservation.
  • Envisaging a very simple noninvasive technique of establishing the provenance Neolithic jade axes (most them, even those found in Scotland, come from Alba, in Piedmont, Italy), based on the position of two diffraction peaks.
  • Proposing and demonstrating the feasibility of dating frescoes based on the preferential orientation of hematite grains toward the earth Magnetic field at the moment of their painting.

 

At the GCI:

  • Brought to the Getty the CT-scan technique for bronzes and fostered the development of laser speckle interferometry that allows detecting at distance loose pieces of plaster, dangerous for visitors.
  • Envisioned and helped to design and produce the noninvasive portable XRD/XRF instrument named DUETTO, a tool that substantially changed the way of identifying compounds, not just elements, in works of art.
  • Introduced, in the early stages of its development, an imaging technique called Reflectance Texture Imaging (RTI), which, by taking many pictures from different direction of the light, allows moving on the computer screen, with a touch of the mouse, the light direction on the object.
  • Perfected the Visible Induced Luminescence, VIL, of Egyptian Blue that he discovered in 1995 and Giovanni Verri adapted to imaging in 2006. He made the technique completely portable, adding flashes and filters, and making it possible to image paintings in the presence of day light.
  • His interest in imaging brought another technique of great interest: Electron Emission. Similar to x-ray radiography but working in reflection mode, it gives information of the first 40-50 microns of surface only, independently from what there is behind.
  • He optimized a simple procedure to rectify, superpose and cross-fade images of various kind, thus making very simple the visual comparison of images derived by different techniques.
  • In strict collaboration with a professor from Granada University, he developed a procedure, SmART_scan, that simulates the imaging of an XRF-scanner, based on a much smaller number of point analysis. This program works well using XRD or Raman data, thus mapping substances rather than just elements.

 

Since retiring in 2013, he represented GCI at the ICCROM Forum. He lectured at ArchMat and for a two year masters program in Thessaloniki and Fes.

He also conducted workshops at the Pratt Institute of New York and the University and Museums in Puerto Rico on the noninvasive x-ray diffraction technique he helped develop.