Mark Richter of the TAHG is currently leading the scientific examination of the monumental polychrome choir screens in the Church of Our Lady in Halberstadt, Germany (dated c.1220) and the St. Nicolai church in Eilenstedt, Germany (dated c.1200). Both works are located in the former Diocese of Halberstadt which comprised large parts of the north-east of the Harzvorland that now belongs to the German state of Saxony-Anhalt. It is striking that in this particular region a unique abundance of medieval plaster works survives, that stand out because of the variety of working techniques and the impressive use of colour for their polychromy. The craftsmanship and artistic skill of the unknown masters were highly developed and resulted in some of the most splendid medieval sculptures, that are outstanding even in a wider European context.
The choir screen in the Church of Our Lady in Halberstadt is exceptional for its artistic quality. The different elements of this work are impressive not just because of the quality of the sculptural decoration but also for the well-preserved medieval polychromy in many areas, which was the main focus of the scientific investigation. The preliminary research has been conducted since 2003 by an interdisciplinary team of conservators, scientists and the State Department for the Conservation of Monuments of Saxony-Anhalt (Landesamt für Denkmalpflege und Archäologie Sachsen-Anhalt, Halle). The main emphasis was placed upon the exploration of the history of the object and earlier restoration efforts. Since 2003 the project has been led by the conservator-restorers Torsten Arnold and Daniela Arnold. Corinna Scherf and Torsten Arnold (Landesamt für Denkmalpflege und Archäologie Sachsen-Anhalt, Halle) are the main partners of the Eilenstedt choir screen project.
The scientific examination of the polychromy of both choir screens is a collaboration involving several partners and international specialists. It includes examination of the polychrome surface with stereomicroscopy and other imaging techniques (raking light photography, ultraviolet light photography), as well as the study and analysis of microscopic paint samples (mounted and unmounted) in the research laboratories of the Technical Art History Group and the Imaging Spectroscopy and Analysis Centre (ISAAC) at the University of Glasgow, using optical microscopy, fluorescent staining and scanning electron microscopy coupled with energy-dispersive X-ray microanalysis (SEM-EDX). Additional advanced analytical techniques are being performed by other external partners. The Doerner Institut, Munich, is undertaking Gas Chromatography Mass Spectrometry (GC-MS) and Amino Acid Analysis (AAA), two techniques that are ideal for providing detailed chemical information on the organic materials found in paint samples, especially binding media. Fourier Transform Infrared imaging (FTIR-imaging) will be carried out at Bern University of Applied Sciences in their Art Technological Laboratory to allow for a more detailed analysis providing layer and site-specific information as well a much more secure interpretation and understanding of the analytical results obtained with GC-MS, AAA and fluorescent staining. The red lake pigments were analysed by the Royal Institute for Cultural Heritage (KIK-IRPA, Brussels) using High Performance Liquid Chromatography coupled with Diode Array Detection (HPLC-DAD).
The project is collaboration between an interdisciplinary team of conservators, scientists and the State Department for the Conservation of Monuments of Saxony-Anhalt (Landesamt für Denkmalpflege und Archäologie Sachsen-Anhalt, Halle).