Welcome to the Research Group "New Techniques for Ancient Materials"
We study physico-chemical processes in natural and cultural materials, with a focus on materials degradation and the development of innovative methods for investigating of composite, multiscale materials.
We are developing various
synchrotron and simulation techniques, from X
(X-ray absorption spectroscopy, X-ray diffraction, X-ray
tomography) ... to A (Algorithms for image processing
and Monte Carlo simulations).
2-Year Postdoctoral Fellowship in image processing!We are looking for applicants with strong computer skills and expertise in image processing to develop and further strengthen our tomography work. A complete description can be found on the HKB website. Applications must be made online before September 20th. We are looking for your application!
SNF professorship in Heritage Sciences prolongated.The request for a two-year prolongation of the professorship has been approved by the Swiss National Science Foundation. Following our previous work, it will focus on the development of microimaging techniques for the study of photochemical pigments and the development of tomography-based methodologies for porous archaeological materials. A summary for the layman can be found here (en Français)
Blue Horizons.The Swiss National Science Foundation has highlighted our research on Prussian blue in the Research magazine Horizons of December 2015.
ODE bleue. The synchrotron SOLEIL has highlighted our research on the photochemistry of Prussian blue done with energy-dispersive X-ray absorption spectroscopy at the ODE beamline.
Our proceedings about anoxia and light fading of Prussian blue by time-resolved XAS is accepted for the open source journal of IOP Physics.
C. Gervais, M.A. Languille, G. Moretti, S. Reguer, "Time resolved XANES illustrates a substrate-mediated redox process in Prussian blue cultural heritage materials", 16th International Conference on X-ray Absorption Fine Structure (XAFS16), Germany, in press. See Publications.
Our study on radiation damages in the microspectroscopic analyses of historic paintings is accepted in Applied Physics A.
C. Gervais, M. Thoury, S. Reguer, P. Gueriau and J. Mass, "Radiation damages during synchrotron X-ray micro-analyses of Prussian blue and zinc white historic paintings : detection, mitigation and integration", Applied Physics A, in press. See Publications.
Our study on the redox chemistry of Prussian blue in cellulose investigated by time resolved XANES is in Langmuir.
C. Gervais, M.A. Languille, G. Moretti, S. Reguer, "X-ray Photochemistry of Prussian Blue Cellulosic Materials: Evidence for a Substrate-Mediated Redox Process", Langmuir, 31:8168, 2015.See Publications.
But what is actually heritage science...?
There is often the misconception that scientific investigation of cultural heritage materials is as old as the objects themselves and does not deserve to be considered as a research field for itself. Here a short answer recently sent to a reviewer about the publication of cultural heritage studies in general chemistry or physics journals:
"The application of standard analytical techniques to the characterization of cultural heritage artefacts is called art technology and exists since decades. The study of those same artefacts to understand their physico-chemistry has developed only recently but is now becoming accepted as a research domain for itself, with the name of heritage science. Like any other research domain, some studies focus on original artefacts or on aspects specific to those artefacts. Those studies are indeed better suited for a journal specific to heritage science. But like in any other research domain, some studies deal with more general, universal aspects of material sciences that may be of interest to a broader readership. [...] I believe that heritage materials have their own existence and should be recognized as they are: fascinating for the broad, topic of research for a few, but and especially, promoters of refreshing views and ideas through their intrinsic transdisciplinarity."
Our paper on corrosion makes the front cover of JAAS.
The issue 30 of Journal of Analytical Atomic Spectrometry features our paper dedicated to the role of the porosity on the corrosion of archaological artefacts.
We used laboratory and synchroton X-ray tomography to highlight the role of multiscale porosity in the corrosion process of iron rebars from the Cathedral of Orléans. Thanks to a combination of image processing, topological tools and chemistry information, we could demonstrate that the porosity is constantly evolving in this type of highly heterogeneous materials and must be taken into account in the prediction of corrosion.Reference: "Degradation mechanisms of reinforcing iron rebars in monuments: the role of multiscale porosity in the formation of corrosion products investigated by X-ray tomography" Mathieu Jacot-Guillarmod, Olivier Rozenbaum, Valérie L'Hostis, Philippe Dillmann, Delphine Neff and Claire Gervais, J. Anal. At. Spectrom., 2015, 30, 1600-1609580--587 DOI: 10.1039/C4JA00388H
Our study on the redox chemistry of PB textiles is
published in Heritage Science.
"Light and anoxia fading of Prussian blue dyed textiles", C.Gervais, M.A. Languille, S. Reguer, C. Garnier, M. Gillet, Heritage Science 2014, 2:26. See Publications.
On the interest of transdisciplinarity.
The interest in studying ancient materials to understand new ones is gaining ground. A recent review of Gibson et al. in JAAS on "Atomic spectrometry update. Review of advances in the analysis of metals, chemicals and functional materials" cite our work in the following terms: "In an example of the fundamental study of the chemistry of colours and the mechanism of colour fade, Gervais et al.(74) presented a study of Prussian blue (PB), a dye widely employed in various artworks and one which exhibits some interesting magnetic and optical properties. The fading of PB is due to the reduction of FeIII to FeII and is strongly dependent on the substrate. The authors examined the role played by the substrate in affecting the structure of PB and how this modifies the redox process. They employed Fe-K-edge XAS on faded and unfaded samples to show that the structural changes in PB occur by contact with the substrate prior to fading. They proposed a roadmap to investigate further the highly complex processes involved in the fading of PB. This reviewer believes that this application may be of interest to those involved in surface coatings and inks."
Oral presentation at the World Conference on
Neutron Radiography (Grindelwald, Switzerland).
Mathieu Jacot-Guillarmod presented a talk entitled "Neutron tomography as a non-invasive technique to assess dechlorination treatments of archeological iron artefacts"
Oral presentation at the Synchrotron Radiation for
Art and Archaeometry (Paris, France).
Claire Gervais presented a talk entitled "Degradation mechanisms of reinforcement iron rebars in monuments: influence of porosity on the formation of corrosion products studied by X-ray tomography."
The Swiss newspaper "Le Temps" is speaking about our
work on Prussian blue.
The article reviewed some of state-of-the-art techniques (including synchrotron) used to tackle the complex compositions and physico-chemical processes happening in cultural heritage materials. Nice pictures that depict our work on Prussian blue are available here (images 6-8): "Les mystères de la matière"
The inside front cover of JAAS is
The issue 10 of Journal of Analytical Atomic Spectrometry features our paper dedicated to the role of the substrate on Prussian blue photoreduction.
In this work, we discuss the multiple internal and external factors playing a role on the photoreduction of Prussian blue in paper-based artefacts. The study is based on model samples prepared with known materials and controled manufacture. By means of UV-visible, X-ray absorption and Raman spectroscopies, the type of paper substrate, the concentration and dispersion of the pigment within the fibers as well as the influence of additives could be highlighted as major factors responsible for Prussian blue fading.
Reference: "Why does Prussian blue fade? Understanding the role(s) of the substrate" Claire Gervais, Marie-Angélique Languille, Solenn Réguer, Martine Gillet, Sébastien Pelletier, Chantal Garnier, Edward P. Vicenzi and Loïc Bertrand, J. Anal. At. Spectrom., 2013, 28, 1600-1609 DOI: 10.1039/C3JA50025J
Heritage Science: a new journal for scientists working in cultural heritage.
This open-access peer-reviewed journal has been designed to be a platform for all scientists working in/for cultural heritage and covers various research fields, such as understanding physico-chemical and biological degradation processes of cultural artefacts, developing and applying specific analytical and imaging methods, and designing statistical methods and algorithms for data analysis. For a complete scope, see website.