Recently, conservation and preservation of our cultural heritage has become a topic of major concern within Europe. Except in countries such as Italy and Greece where care for the cultural heritage is part of the scientific establishment, only a very limited number of research groups that have large experience in the use and development of state-of-the-art scientific methods of analysis spent considerable research efforts on cultural heritage-related problems. On the other hand, there is an increasing need for non-destructive investigation of cultural heritage materials, as sampling is often restricted because of the value or the uniqueness of the artefact. Even when sampling is allowed, non-destructive testing offers the possibility of obtaining more information from a sample, as complementary techniques may be applied on the same sample.

This research program will have two main fields of research:

- 3D imaging of the painting support and paint multilayers

- elemental and molecular analysis on the different layers composing the art object.

3D imaging allows to obtain information of the pictorial layers and varnish without requiring to sample, enabling the identification of modifications(restoration, falsification...) and the influence of various external factors degrading the state of the pictorial layer (moisture, developments of moulds,...).

Studies by physicochemical spectroscopic methods provide information on the composition of the pigments and the dyes, the varnishes, the binders and the metal sheets. This allows the characterization of discolorations and degradations of the pictorial layer on the surface and in depth. The techniques on which we want to focus have a great potential to carry out non-destructive analyses and to provide three-dimensional information:

- micro X-ray fluorescence (-XRF) and nuclear microprobe for elemental analyses,

- micro X-ray diffraction (µ-XRD) and X-ray absorption spectroscopy (XAS) on the one hand and micro IR and micro Raman spectroscopies on the other hand for structural and molecular analyses, respectively,

- micro X-ray tomography (µ-CT) for obtaining information on the three-dimensional structure.

The validation of these non-destructive techniques will be achieved by comparison with micro-sampling techniques. The main objectives of this project are:

WP1. Virtual sectioning and 3D imaging by µ-CT

WP2. The development of elemental and molecular analytical techniques

WP3. The development of mobile analytical tools

WP4. The identification and characterization of the support and of paint layers

WP5. Transformation and degradation of paint layers

WP6. Improving access to state-of-the-art analytical tools for cultural heritage researchers

All the objects studied in the NACHO's project can be analyzed by the following techniques :

- micro samples : XRD, SEM-EDX, FT-IR, GC-MS, HPLC, Raman Spectroscopy, Micro-CT, XAS.

- Direct and in situ analysis: PIXE, XRF, RBS, Raman Spectroscopy, Micro-CT, XRD, XAS