António Candeias
HERCULES Laboratory – University of Évora, Portugal

The range of analytical instrumentation currently available for heritage research and conservation is broad and encompasses both in-situ non-invasive techniques and micro-analytical and high-resolution laboratory techniques. Since each technique gives its own type of information and has its own suitability strengths and weaknesses, a previous assessment is essential to avoid a disorientated and useless examination. One of the problems is the use of a limited analytical methodology or tendency to focus on specific research details that result in incomplete information that can be problematic for carrying out conservation interventions or historical studies. Furthermore, in most cases, no single analytical technique can determine the full composition and/or structure of an object and provide valuable conclusions. In most cases a compliance of the results from several complementary techniques must be employed. Sampling is often carried out to allow the analysis of art/heritage objects but recent advances in imaging and non-invasive point and mapping techniques are changing this situation and allowing the development of comprehensive non-invasive studies and integrated conservation projects. In this talk we will explore new non-invasive and imaging techniques and their introduction and application in conservation and heritage science projects at HERCULES Laboratory.

Francesca Rosi
“Giulio Natta” Institute of Chemical Sciences and Technologies (CNR-SCITEC), Perugia, Italy

The identification of chemical compositions whilst fully respecting the object’s integrity are all intrinsic and well consolidated aspects of the state-of-the-art Heritage Science. If the available single point analytical investigations can lead to powerful diagnostic results, the most comprehensive answer to the complex and challenging questions of heritage professionals requires acquisition of a knowledge which generally goes beyond the chemical composition of the localized area/point. To give comprehensive answers to heritage professionals questions, it is essential to integrate the chemical identification of materials with their macro-scale semi-quantitative spatial distribution associating molecular information to colours, hues, brushstrokes and more generally to what is visible to the naked eye. In other word, analytical chemistry must provide the image of the distribution of the chemical composition, information that can be more easily interpreted and more profitably discussed/evaluated by experts of the CH field.
Driven by this, in the last years Heritage Science efforts have been directed through the development and application of analytical hyperspectral imaging/scanning techniques experiencing a wide diffusion as new powerful tools. In the same way, the European Research Infrastructure for Heritage Science (E-RIHS- considered key the strengthening of the analytical hyperspectral imaging/scanning facilities of the mobile laboratory hy-MOLAB through the development and application of advanced technologies able to inform about the chemical composition and distribution at the macro-scale.
More traditional and consolidated imaging techniques as well as new imaging possibilities offered by E-RIHS probing different chemical properties, probing unexplored spectral ranges, and based on multimodal/integrated systems will be presented. Developments and tests on laboratory mock-ups as well as in situ case studies will be discussed. Hints on data processing and chemical images reconstruction will be also done.

Matthias Alfeld
Delft University of Technology, Nederland

The last years have seen a significant development in the imaging techniques used for the investigation of cultural heritage objects. Commonly the imaging techniques are evaluated in parallel and their results are interpreted to obtain an insight into the material character of an object. In this talk recent approaches to the evaluation of fused imaging data, such as XRF photography, RIS (VNIR&SWIR), will be presented, their potential illustrated in case studies and their perspective will be discussed.

Victor Gonzalez
École Normale Supérieure Paris-Saclay, CNRS, PPSM, France

This communication will present chemical research carried out at the multi-scale to coherently probe the production, formulation and reactivity of ancient pictorial matter. Results obtained both on model systems and on historical paintings and samples will be presented. Special focus will be placed on inorganic pigments used by painters in different historical periods, from the Italian Renaissance to the Dutch 17th c. and finally the early 20th c.

Diego Tamburini
The British Museum, London, UK

The invention of early synthetic dyes in 1856 marks a pivotal point in economic, societal and art history. The development and spread of these new commercial products were so fast that in a few decades the European textile-making industry was completely revolutionised, and these new colours were exported from Europe to every corner of the world. However, the driving forces that guided the import/export and the introduction of these materials into millenary traditional dyeing practices are complex and require cross-disciplinary expertise to explore them.

With a focus on 19th century Central Asian and Southeast Asian textiles, this talk addresses the challenges related to the identification of early synthetic dyes in historic objects from an analytical point of view and provides examples of how to use this information to refine the dating and enhance our knowledge of museums’ textile collections as well as of the changes in traditional dyeing and textile-making practices that occurred in the 19th century.

Stamatis C. Boyatzis
Department of Conservation of Antiquities and Works of Art
University of West Attica, Athens, Greece

Non-invasive identification of natural resins used in varnished artwork surfaces has been made easy by applying reflection infrared spectroscopy. However, varnish formulations, developed by mixing various resins, and occasionally, heated siccative oils, induce molecular changes depending on composition, heating conditions, and often on the underlying layers that hamper the certainty of identification. Additionally, various physical phenomena, such as irregularly reflected infrared beams on uneven surfaces, and varnish transparency, are among the factors that add to the complexity of the spectroscopic information. Results from the research in our lab will be presented, where the strengths and limitations of reflection infrared spectroscopy applied on varnished surfaces will be discussed. Comparisons with spectra from standard sampling techniques, such as scraped powder samples and solvent-extracted organics directly from the varnish layers, highlights the impact of chemical and physical complexity of coated surfaces and its influence on the final spectra.

Francesco Grazzi
Consiglio Nazionale delle Ricerche Istituto di Fisica Applicata “N. Carrara” (CNR-IFAC), Tuscany, Italy & Istituto Nazionale di Fisica Nucleare, Laboratorio di tecniche nucleari per l’Ambiente e i Beni Culturali, Florence, Italy

In recent years, neutron imaging and neutron diffraction affirmed as reliable and meaningful methods of investigation for non-invasive analysis of metal artefacts. Several important questions related to manufacturing technology of historical and archaeological metal artefacts were solved thanks to these techniques: choice of the composition of the alloys, thermal and mechanical treatments, optimization of the technological process. This presentation shows a brief overview of the method and some of these results.

Isabel Tissot
Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys), NOVA School of Science and Technology, Caparica, Portugal.

Analytical techniques are used in conservation studies of cultural heritage metallic objects to deepen our knowledge of corrosion processes, highlight marks of use, assess treatments, and define conservation strategies.

In a model of continuous iteration, as new conservation challenges arise, new analytical strategies are developed, and as new technological developments emerge, it is possible to detail the conservation questions still open.

This talk presents the open questions in the conservation of cultural heritage metal objects and how research based on analytical techniques approaches these challenges.