Door Yu Han Hsu, intern at Restauratieatelier Marjan de Visser
The annual NICAS Project Day was hosted and organised by the Netherlands Institute for Conservation, Art and Science (NICAS) and took place december 11th at the Rijksmuseum. During the dayvarious ongoing research projects were presented, including multi-year full research plans and exploratory seed money projects, which have been supported by the Netherlands Organisation for Scientific Research (NWO). The 18 lectures presented on the project day can be divided into two categories: 1) updates on projects funded in 2015 and 2) introductions on projects funded in 2018. All the projects, which are carried out in collaboration between various academic institutions, are devoted to fostering the quality of art interpretation, preservation, and presentation through the multidisciplinary framework of humanities and the sciences.
Six full projects and five seed money projects were funded by NWO after the first call for proposals by NICAS in 2015. These projects explored the potential of various aspects of art materials, for instance by challenging historical reconstructions or developing patterns to examine and reflect the ways in which researchers evaluate and manipulate research materials.
Recipes and Realities, a full project led by Professor J.F.J.H. Stumpel, aimed to reconstruct how 17th-century painters achieved ideal and lifelike visual effects in still life paintings. The recipes for creating surface textures of different objects, described in the book “De Groote Waereld in’t Kleen Geschildert” (1692), written by Willem Beurs (1656–1700), were used as the main source for gaining a better understanding of painters’ techniques used in this period. Furthermore, a scientific examination of pigment layers in 17th-century still life paintings was carried out to precisely reconstruct painting procedures and to reveal the secrets of the masters using computer models. This project combines different human perceptual experiences. It provides a link between art history and physicochemical studies, exploring how painters’ techniques make connections in the human perceptual system to create pictorial credibility, by using different materials and objects in paintings.
Professor G.R. Davies, Professor M. Tromp, and Dr. P. Taheri’s projects also aimed to reconstruct aspects of art history by paying attention to the different characteristics of metal objects. Multi-isotopic Analysis of Early Modern Art: Linking Origin, Trade, and Production of Raw Materials with Provenance Research, a full project led by Professor Davies, aimed to establish the geochronology of metals (raw materials) to determine when and where works of art were produced. With an emphasis on isotopic techniques and data to determine the age and origin of the raw material, this project adopted laser systems to minimize the size of the sample extracted from objects. Statistical methods were used to construct isotopic patterns as references for provenance research. This data further elaborated on the global history of the trading and manufacturing of raw materials. In addition, the data sheds light on how, when, and where the raw material was used to create the artwork.
Professor Tromp’s In-situ and Conservation on Metal-containing Works of Art studied the aging process of metals under different environmental conditions to reflect the original appearance and appropriate future conservation treatments of artworks. In addition to using X-ray imaging techniques, Professor Tromp’s team developed an instrument to detect subtle changes in metal properties in order to predict whether the structure of an artwork will remain stable.
Another project on metals was directed by Dr. Taheri. It focused on examining and characterising the degradation mechanisms of organic polymers on metal objects, which were often used to decorate or coat items. As the layer of organic polymers easily decays over time, understanding its degradation process is essential for the conservation of the objects.
The Delftware Ceramic Glaze by Dr. J. van Campen and The Gilt Leather Artefacts by Dr. R.M. Grove, both used historical reconstructions to research ceramic and gilt leather. Dr. van Campen focused on different types of glaze used on Delftware ceramic and the relationships between the original colors of glazes and their elemental composition. With the aid of laser techniques, the composition of different glazes can be analysed systematically. The current challenge of this project is metamerism, a phenomenon resulting from a mismatch between the pigments used by conservators for retouching and the original glaze. In order to improve the conservation treatment of Delftware ceramic, this project developed a computer program to calculate the original color from a database of pigment reflectance spectra. The result is expected to assist conservators in selecting the right pigments for their treatments and aid art historians in distinguishing between metamerism and the original appearance of objects.
Dr. Grove’s research deals with the aging processes of gilt leather, which was a form of fashionable and fancy interior wall-hanging in the early modern period. The aging processes of gilt leather have been a challenging issue due to the complex composition of organic and inorganic materials, such as leather, animal glue, silver-leaf, varnish, and oil paint. In early conservation treatments of gilt leather, oils and waxes were used without sufficient consideration of their composition. This often caused negative outcomes, such as the darkening of color and changes in gloss, as well as the stiffening of the leather. In this project, a 3D hyperspectral imaging system, a non-destructive method for examining paintings, proved to be a useful tool for revealing the original features of gilt leather, in particular, in the case of the gilt leather panel housed in the Maastricht town hall. Specifically, the system detects the condition of different components and compounds, such as thin varnish and paint layers. This data is analysed using a software analysis platform (TIPP), which provides a mapping of the used pigments and predicts the possible degradation of paint layers in the future. The recent results have been published in Lasers in the Conservation of Artworks XI, Proceedings of the 2016 International Conference LACONA XI.
Two other full projects led by Professor P.D. Iedema and Dr. J.A. Poulis related to the restoration of artworks. Professor Iedema concentrated, in particular, on binding media for pigments. 3D imaging techniques were used to visualize degradation patterns of binding media and their effect on colour. The final goal of the project was to create a typological model to predict future aging of oil paintings. This data can assist conservators in determining appropriate conservation treatments. Dr. Poulis focused on the chemical and physical aging of adhesives, also aiming to improve conservation strategies, particularly when choosing adhesives to consolidate flaking parts of artworks.
In addition to conservation science, Scientific Reasoning in Art by Dr. M.J.N. Stols-Witlox and A Visual Analytics Approach for Stylistic History of Paintings by Professor M. Worring explored new ways to improve art history research methods and tools. Dr. Stols-Witlox used Bayesian networks, a model used in mathematics, to quantify the actual value of different pieces of evidence adopted by art historians through archival research and scientific examination. This measurement intends to decode in what way the supposed authenticity and age of artworks are affected when a researcher is faced with abundant or insufficient information. Professor Worring has developed software that allows art historians to use a convenient and detailed analytical tool to understand the evolution of art styles overtime. The software can also assist art historians in easily finding and categorising similar artworks within a huge collection.
With a focus on data science in 2018, four full projects and four seed projects were awarded funds to develop multiple research strategies and seek optimal preservation of cultural heritage.
Dr. K. Keune’s 3D Understanding of Degradation Products in Paintings concentrates on the degradation of arsenic and lead-containing pigments. Like Professor Iedema’s 2015 project, Dr. Keune adopts 3D imaging techniques to visualize degradation and migration processes in the paint layers. Data fusion technology is used to determine and improve the 3D model. The generated model is expected to give a better understanding of how different painters’ layer build-up influences the style and condition of paintings.
Two other projects are also related to the degradation and condition of artworks: Irradiation Passport for Art by Professor Dr. M. Tromp and A Multi-scale and Uncertainty Approach for the Analysis of the Aging of Timber Art Objects Adhesively Bonded by Animal Glues by Professor Ir. A.S.J. Suiker. The former explores the effects of radiation on art, which are not yet fully understood. The latter focuses on the influence of degrading glue on wooden objects.
Beeldvorming: A Non-invasive Look Inside Statues by Dr. L. van Eijck, and CT for Art: From Images to Patterns by Professordr. K.J. Batenburg both intend to test new technologies. Dr. van Eijck addresses three non-invasive methods: neutron tomography, gamma tomography and gamma spectroscopy, to reveal the interior structures of metal art objects, such as bronze sculptures. In addition to these examination techniques, dr. L. van Eijck also intends to transform data into a 3D model to represent a sculptor’s approach to constructing his work. In the second study, Professor Batenburg aims to apply 3D scanning techniques, especially computerized tomography (CT) scanning, to see the inside of objects. Moreover, CT scanning is expected to trace the finger prints and tool marks of artists, and the wood growth rings inside wooden objects. On the one hand, the outcomes give information on the making process and the tools that were used. On the other hand, the hidden rings inside the wood are useful for dating. This is the first time that CT scanning has been applied in the scientific examination of art. Furthermore, during this project software was developed to create 3D images and automatically analyse information about the origin and condition of the object.
Another project employing CT scanning is led by Professor dr. ing. M.R. van Bommel, Automated Interpretation of X-radiographs and CT Scans to Assess Islamic Carpet Construction. This project examines 16th– and 17th-century Islamic knotted-pile carpets with a focus on the woven structures.
The last two projects are Imaging, Identification, and Interpretation of Glass in Paint by Professor dr. H.H.M. Hermens and 21st Century Connoisseurship: Developing Smart Tools for the Analysis of 17th-century Paintings by professor dr. R.G. Erdmann. Professor Hermens intends to address the question: Why did early modern painters add glass to paint layers? Through interdisciplinary collaboration amongst art historians, data scientists, and conservation scientists, 17th-century painters’ recipes and the painting collections in the Rijksmuseum are analysed in order to answer the above question. The result is expected to show whether the glass component plays a role in improving transparency or simply demonstrates the painter’s desire to achieve a glassy effect. Professor Erdmann challenges the method of determining the authenticity of paintings by old masters through the development of digital tools. The tools should enable art historians to compare scientific evidence and original paintings in an easier and quicker way. More importantly, the tools allow tracking and analysis of similarities and differences between paintings, without taking into account the painted surface or deeper layers. In this way, new insights are gained into controversial paintings, aiding the researcher in questions of coöperation between artists, dating and authenticity.