The Art Museum of Estonia launched a large scale-project in the autumn 2013, the objective of which was to complete the conservation work on the retable of the high altar of St. Nicholas’ Church that was discontinued some twenty years ago. The work was accompanied by a comprehensive programme of technical and art historical analysis.
Coordinator: Hilkka Hiiop
Team: Hedi Kard, Merike Kurisoo, Grete Nilp, Kaisa-Piia Pedajas, Tarmo Saaret
Research team: Alar Läänelaid, Hembo Pagi, Riin Rebane, Andres Uueni, Signe Vahur
Designer: Villu Plink
Koostööpartnerid: Estonian Academy of Arts, Estonian Open Air Museum Conservation and Digitization Centre Kanut, Estonian Enviromental Research Centre, Archaeovison R&D, University of Southampton, University of Tartu, Chair of Analytical Chemistry, University of Tartu, Department of Geography, Estonian Tax and Custmos Board.
1970 Beginning of large-scale conservation work
Several of Estonia’s most important objects of art were sent to restoration centres in Russia to be conserved in the 1970s, among them the altarpiece of the high altar of St. Nicholas’ Church. Nikolai Bregman, who was then still a young conservator, supervised the work. In parallel with conservation work, extensive material-technical analyses were carried out using state-of-the-art technology in Russian laboratories. For instance, the composition of the pigments and the type of binder used in the painting was determined. Infrared photography was also partially carried out. The restoration work supervised by specialists from Moscow was discontinued in the early 1990s in connection with the restoration of Estonia’s independence. By that time, the wings of the altarpiece and about half of the large polychromatic sculptures of saints had been restored.
2013 Research and conservation project The Rode Altarpiece in Close-Up
In the autumn of 2013, the Art Museum of Estonia initiated a large-scale project focusing on investigating and conserving the retable of the high altar of St. Nicholas’ Church. The double-winged retable is one of the most impressive and better-preserved examples of late medieval Hanseatic art in Europe. It was completed in 1481 in the workshop of the wellknown Lübeck master Hermen Rode. The objective of the work begun by conservators from the Art Museum of Estonia in the autumn of 2013 was to bring to completion the conservation of the sculptures situated within the corpus of the altarpiece and the elaborate décor surrounding them, and to restore the appearance of the altarpiece’s most festive view in its entirety.
The Use of Imaging Methods in Documenting Heritage
Various methods were used as documentation solutions in the course of this project, including photogrammetry, 3D scanning, multispectral examinations (near-infrared, ultraviolet and X-ray) and animated photography using side lighting.
- Base drawings containing carbon, such as the pencil, charcoal or ink that are beneath the layer of paint, created using various techniques, can be stored by way of near-infrared photography (720–1060 nm).
- The display of ultraviolet fluorescence (360–400 nm) makes it possible to gather information on changes later made to the painting layer and different materials.
- In conducting roentgenographic examinations, we used the Estonian Tax and Customs Board’s portable X-ray apparatus and the stationary X-ray apparatus belonging to the University of Tallinn Institute of History. With the help of X-rays, it was possible to see through parts of the altarpiece and wooden figures of interest, which made it possible to obtain further information on the methods of work used in Hermen Rode’s workshop and to look at the internal structure of different parts of the work of art.
- RTI (Reflectance Transformation Imaging) is a method of photography that uses reflected side lighting to reveal surface changes in the object under examination. This method is useful for the detailed examination and presentation of different objects, such as sculptures.
The Sciences in the Service of Art Research
- Through exact scientific research, it was determined which materials and techniques Hermen Rode used in making this altarpiece. One branch of analytical chemistry is instrumental analysis, in other words the use of different instruments for several examinations, including the identification of the composition of complicated materials (paints, varnishes, adhesives etc.).
- Chemical research on Hermen Rode’s altarpiece began with non-destructive analyses conducted using portable equipment in situ at the works of art and, thereafter, analyses continued using (semi-)destructive methods, for which tiny pieces of original material had to be removed from the work of art. These analyses were carried out in the University of Tartu chemistry laboratories.
- Among the portable instruments, the hand-held X-ray fluorescence (XRF) apparatus is being used more and more. This method identifies the composition of elements at a selected point on an object using X-rays.
- Dendrochronology is a science of studying tree rings with the aim of determining the age of trees and wood as well as identifying connections with various ecological, including meteorological factors, and solving corresponding problems. The wooden sculptures of the altarpiece are made of oak wood. Some sculptures were removed from the corpus of the altarpiece for dendrochronological examination.
Science and Practice
To ensure that the information created within the framework of this project does not remain oriented towards only one object and that it can be applied in researching different types of heritage, broadbased educational work integrating knowledge in the humanities and the natural sciences has developed into an important part of this project.A series of international workshops associated with the project are intended for students and specialists in related professions from institutions of higher learning.
- The programme Question of Conservation. Polychrome Wooden Sculptures of the High Altar retable of St. Nicholas’ Church (11-15 November 2013), led by Dr. Arnulf von Ulmann from Germany and Nikolai Bregman from Russia and dealing with methods for conserving polychromy, opened the series of workshops and the entire project.
- The focus of the second workshop, Rode Imaging Event (15-18 May 2014), was the points of interaction between information, communication and imaging technologies and cultural heritage. This event brought together 10 top-level experts from Europe, who shared their knowledge and experience with each other and with people involved in the speciality in Estonia.
- The Rode Investigation Workshop (20-23 October 2014) dealt with instrumental analytical methodology connected with the fields of chemistry and physics, and with its role in heritage studies (investigation of pigments, binders, coating layers and other such matters).
- The workshop Wood and Art (16-18 February 2015) dealt with the possibilities of researching the historic uses of wood in heritage objects, involving dendrochronology and its various applications, the interpretation of tool marks and types of wood, etc.