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This paper gives an overview of research in or associated with the pan-European network COST Action G8, which aims at achieving a better preservation and conservation of our cultural heritage by increasing the knowledge of art and archaeological objects through advanced chemical and physical analyses. The paper is focussed on the use of various analytical techniques for the examination of cultural heritage materials and includes research examples on painted works of art, ceramics, glasses, glazes and metals. In addition attention is drawn to advances in analytical instrumentation, for example the development of portable techniques to perform analyses on site, and to the need for collaboration between people directly involved in the field of cultural heritage and analytical scientists. D

We describe the construction of an electrochemical cell of the Bragg type suitable for in situ synchrotron X-ray measurements on rough, heterogeneous metals such as cultural heritage alloys and simulants with corroding or passivated surfaces. The cell features a working electrode, which may be moved under remote control from a position close to an X-ray window to full immersion in the electrolyte. A pocket of electrolyte in contact with the bulk can be maintained on the working electrode surface at all times. Its thickness (typically 100-200 µm) can be controlled by adjusting the working electrode position and, independently, altering the conformation of the X-ray window with hydrostatic pressure. Alternatively, the electrode may be lowered into the bulk of the electrolyte. Early results from the cell showing a time-resolved study of the reduction of nantokite to cuprite in sodium sesquicarbonate, accompanied by corrosion potential measurements obtained in parallel, are presented here.The application of electrochemical techniques for the stabilization, cleaning, and protection of metallic cultural heritage objects from silverware to battleships 1-6 is proving to be extremely effective, and research in this area has increased significantly in the past 10 years. The value and uniqueness of some of the objects involved, together with other issues such as their location, means that all conservation treatments must be thoroughly understood and tested, preferably before first use. The consequences of failure range from the loss of an irreplaceable museum object to serious environmental damage (e.g., in the case of fuel leakage from a sunken World War 2 battleship). 7 In addition, there is a need for fully qualified but simple in situ monitoring techniques that can be used by conservators, for example, corrosion potential (E corr ) measurements on artifacts stored in stabilizing media (such as marine objects immersed in sodium sesquicarbonate solution). 8,9 There exist many techniques that can be used for the ex situ study of real and simulated surfaces (e.g., analytical electron microscopy, various electron spectroscopies, mass spectrometric techniques 10-13 ). In most cases, these require that the sample is placed in an untypical environment such as a vacuum and the relationship between such measurements and the surface chemistry in the native state is rarely established. Moreover, it is only recently that it has become possible, using these techniques, to observe reactions at the liquid-metal interface as they occur. 10 In 1980, Fleischmann et al. described the first in situ observation of electrochemical reactions at the liquid-solid interface using X-ray diffraction (XRD). 15 A few years later, Fleischmann et al. published some of the earliest designs for electrochemical cells for use with a variety of synchrotron X-ray (SR-X...) techniques. 16 Since then, the use of SR-XRD, synchrotron X-ray absorption spectroscopy (SR-XAS), and electrochemistry has been described by a number of authors, 17-25 many of who...

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The effects of pH and chloride concentration on the electrochemical corrosion of copper in aqueous sodium chloride (NaCl) media were studied at the micro scale using a microcapillary droplet cell and at the macro scale using a conventional large scale cell. Using an experimental design strategy, electrochemical response surface models of copper versus pH and NaCl concentration were constructed with the minimum number of experiments required. Results show that the electrochemical behavior of copper under corrosive media shows significant differences between the micro and macro scale experiments. At the micro scale, the pit initiation of copper occurs at more negative potentials for high NaCl concentrations and alkaline pH values. Also, the micro scale potentiostatic measurements indicate higher stabilised passive currents at high NaCl concentrations and low (acidic) pH values. At the macro scale, the pH is shown to have a greater influence on the corrosion potential. The chloride concentration is the most significant factor in the passive current case while at the micro scale the effect of these two factors on the passive current was found to be the same. The surface morphology of the formed patina on the corroded copper in both micro and macro systems reveal a more significant role of the chloride concentration on the structure and the grain size of the patinas. Finally, micro and macro electrochemical impedance spectroscopy of copper at various NaCl concentrations and pH values demonstrates a different behavior of copper after several potentiodynamic polarization cycles.