The Polychromy of Baroque and Rococo Sculptures and Retables in Germany

The Polychromy of Baroque and Rococo Sculptures and Retables in Germany
The aim of the project is to study polychroming techniques of the Baroque and Rococo period, i.e. the original appearance of wooden sculptures and retables from the 17th and 18th century. "Polychromy" is the technical expression for surfaces of artworks with a multi-coloured or even a monochrome design. The artists who were responsible for the polychrome or monochrome design of these surfaces on sculptures or retables were usually trained painters who also created wall paintings as well as canvas and panel paintings. These were often paid more than the sculptors themselves. Polychroming techniques were often influenced or had their origin in paintings and are accordingly sophisticated and complex. A great amount of research is still necessary in this field. With an interdisciplinary approach involving restorers, scientists and art historians we hope to acquire more knowledge in this field more effectively. Since the previous research work, which was supported by the Federal Ministry for Education and Research, mainly focused on blue lacquers on silver leaf, the new research will now be directed towards red, green and yellow lacquers (German: Goldlack) on metal leaf gildings as well as colourless transparent coatings on silver.

In order to obtain reliable results for the fields of art history and the conservation/restoration of historic and artistic works this study will be based on three pillars:

Detailed scientific examination of original and securely dated polychromy: artists' materials and layer structure.
Comparison between the results of the scientific examination and the historic documentary sources (e.g. handbooks, workshop notes) with recipes on polychroming and painting techniques of the 17th and 18th century.
Reconstructions of specific polychroming techniques. This practical realisation/ implementation of the examination results and the information obtained in the historical documentary sources serves as a test for the practicability of the execution, which is hardly described in the sources, and helps give an idea of the artistic intention and how the original appearance may have been.
The examination of cross sections with light microscopy gives us insight into the complexity of polychroming techniques and their multi-layered structure. The analytical techniques that are employed on cross sections and loose samples to identify the inorganic and organic artists' materials used for these complex glazes techniques are: optical microscopy, polarised light microscopy (PLM), fluorescent staining techniques, x-ray diffraction (XRD), scanning electron microscopy (SEM) in combination with energy dispersive x-ray spectrometry and wavelength dispersive x-ray spectrometry (EDX, WDX), direct temperature-resolved mass spectrometry (DTMS), high performance liquid chromatography (HPLC), single-point transmission and reflection-absorption spot analysis FTIR, specular reflection imaging FTIR, and time-of-flight secondary ion mass spectrometry (Tof-SIMS). With the aid of these techniques it is possible to analyse extremely thin layers. A complex sequence of layers is especially evident in coloured lacquers, which were almost exclusively applied to silver leaf.

The detailed knowledge of the historical polychroming techniques to be gained with the aid of these analytical techniques will serve as a basis for appropriate conservation / restoration treatment of these works of art. In addition it will also serve as an aid towards a correct assessment of the original artistic effect of these works of art, which today are mostly in an altered and aged condition that often barely corresponds with their originally intended appearance.

Composition of work group:

Prof. Dipl.-Restaurator Erwin Emmerling, Lehrstuhl für Restaurierung, Kunsttechnologie und Konservierungswissenschaft, Technische Universität München

Dr. Michael Kühlenthal, Hauptkonservator i.R., ehem. Leiter der Abteilung Restaurierung, Bayerisches Landesamt für Denkmalpflege: Projektleitung

Dipl.-Restaurator Mark Richter, wissenschaftlicher Mitarbeiter, Lehrstuhl für Restaurierung, Kunsttechnologie und Konservierungswissenschaft, Technische Universität München

Akad. Oberrat Dr. Günter Grundmann, Lehrstuhl für allgemeine, angewandte und Ingenieur-Geologie, Technische Universität München

Dipl.-Restauratorin Cristina Thieme, wissenschaftliche Assistentin am Lehrstuhl für Restaurierung, Kunsttechnologie und Konservierungswissenschaft, Technische Universität München

Other participating scientists and art historians:

Dipl. Mineraloge Klaus Rapp, analytical consultant, München

Dr. Doris Oltrogge, Kunsthistorikerin, Fachhochschule Köln, Institut für Restaurierungs- und Konservierungswissenschaft

Co-operation partners:

Prof. Dr. Jaap J. Boon, Jerre van der Horst, Molecular Paintings Research Group, FOM Institute for Atomic and Molecular Physics [AMOLF], Amsterdam, The Netherlands

Prof. Dipl.-Restaurator Stephan Schäfer, Faculdade de Ciências e Tecnologia,
Departamento de Conservação & Restauro, Universidade Nova de Lisboa, Portugal

Dr. Maarten van Bommel, Research department, Instituut Collectie Nederland, Amsterdam, The Netherlands

Dr. Caroline Tokarski, Universite´ des Sciences et Technologies de Lille 1, Villeneuve d'Ascq Cedex, France

based at: Lehrstuhl für Restaurierung, Kunsttechnologie und Konservierungswissenschaft, Technische Universität München

Funding: Deutsche Forschungsgemeinschaft (Kennedyallee 40, 53175 Bonn), GZ: EM87/2-2

Project term: 2005 - 2009

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