What can we learn from medieval craftspeople to help preserve our cultural heritage in an uncertain future? The Sticking Stones project investigates the use of wood tar as stone adhesive in cathedral construction and repair. The complex technology hidden within 800-year-old adhesives will be uncovered to develop more sustainable materials for the conservation of architectural stone heritage.
Project
STICKING STONES: Rediscovering medieval wood tar adhesives for stone conservation
Leader
Dr. Bettina Ebert
Researchers
8 researchers from 5 institutions
Funding
Research Council of Norway
Project number 344868
Duration
2024 - 2028
Collaboration Partners
Updates from the project
Get an overview of the latest activities and news from the Sticking Stones research project.
Presentation for NIKU
In March, Silas presented his research plan at the Norwegian Institute for Cultural Heritage Research (NIKU) in Oslo. NIKU is an independent institute for applied R&D and services within the wider field of Cultural Heritage in Norway and beyond.
The aim of this get-together was to present his planned PhD research as part of the Sticking Stones project, to benefit from all the assembled knowledge and experience of colleagues working in neighbouring fields, and to make new contacts.
Having representatives from NIKU, Riksantikvaren, Fortidsminneforeningen, NordicTarNetwork, NorskHåndverksinstitutt, Nasjonalmuseet and restoration companies present shows the great and diverse interest in the topic. Thank you all for participating and sharing your knowledge!
Visit from Trondheim
In January, we held our second successful collaboration meeting with our colleagues from Nidaros Cathedral Restoration Workshop (NDR) in Trondheim. This time the meeting took place in Stavanger at the Museum of Archaeology.
We presented the Sticking Stones project in detail and then went for a site visit to take a close look at Stavanger Cathedral. Our aim was to exchange ideas with other stonemasons at a professional level. Did they make similar observations in Trondheim? How would they approach historic stone carvings today? Would Nidaros Cathedral be a suitable case study?
Thank you very much for the valuable insights and the friendly visit. See you soon!
Participation at a conservation congress in Lima
The Museum of Archaeology recently had the privilege of being represented (for the first time in its history!) with a paper presentation at the International Institute for Conservation’s (IIC) Congress in Lima, Peru. This takes place every other year, and is globally one of the most important events in conservation.
The IIC Congress is a global arena for intellectual exchange and dissemination within the wider conservation discipline. The theme was 'Sustainable Solutions for Conservation: New Strategies for New Times'. Therefore, this was an apt venue for Bettina to present her ongoing research project Sticking Stones. Bettina received a dissemination grant from the EU COST Action POTARCH to travel to Peru and present her paper in-person in Lima.
At the much-anticipated global event that is the IIC Congress, thousands of conservation practitioners, academics, researchers and policy makers gather to address challenges and solutions for the discipline. The scientific program is curated by an international committee that selects circa 40 of the most promising abstracts from many hundred submissions. Selected paper presenters are invited to write a peer-reviewed publication that is published in a special issue of the discipline’s most important and respected journal, Studies in Conservation.
Bettina’s open access publication in Studies in Conservation has proven to be very popular, as it is currently the most read paper in the special issue, with over 1000 reads after such a short time! It was a real privilege to represent the University of Stavanger and the Sticking Stones project on this important stage.
Startup meeting in Stavanger
The research group gathered in Stavanger in November 2024 for the kickoff meeting. Exciting times ahead!
About STICKING STONES
The research project runs from April 2024 until March 2028. The project is led by the Museum of Archaeology at the University of Stavanger, with international collaboration partners based in Norway, the Netherlands and the USA.
Medieval northern European stone churches are at increased risk of damage due to climate change, and forgotten historic materials and techniques may provide the key to saving our architectural stone heritage. The recent discovery of hundreds of medieval wood tar adhesive repairs on Stavanger cathedral in Norway has shed light on a lost historic craft tradition. The STICKING STONES project will rediscover forgotten medieval techniques of construction using wood tar adhesives.
STICKING STONES takes as starting point Stavanger cathedral as case study. This will be combined with extensive fieldwork in Northern Europe to map the broader medieval European context of architectural adhesive use. Intangible heritage and embodied knowledge are key to understanding the craft skills of wood tar repairs across medieval northern Europe, in conjunction with comprehensive material characterization of historic samples. Subsequently, we will test the performance of reengineered wood tar adhesives as sustainable alternatives to synthetic adhesives currently used in stone conservation.
STICKING STONES consists of a multidisciplinary project team with experts from conservation, archaeology, art history, materials science and geology. The team includes a PhD candidate based at the Museum of Archaeology, and a postdoctoral researcher at Delft University of Technology.
Ebert, B. (2024). Learning from the Past: Rediscovering Traditional Medieval Wood Tar Adhesives for Sustainable Stone Conservation and Built Heritage. Studies in Conservation, 69 (sup1), 63–71. https://doi.org/10.1080/00393630.2024.2339728
Ebert, B. and T. Bjelland. (2023). Stuck like glue: Wood tar as a medieval stone adhesive. In Working Towards a Sustainable Past, ed. J. Bridgland. Paris: International Council of Museums, 1-9. https://www.icom-cc-publications-online.org/5601/Stuck-like-glue--Wood-tar-as-a-medieval-stone-adhesive
Knutsen, K. A. (04.06.2025) New discoveries in the cathedral: The choir survived the city fire of 1272, Stavanger Aftenblad.
Larsen, F. Revealing unknown histories about the medieval cathedral, Aftenposten Historie issue 5, 2025, pp.14-21.
NRK TV Distriktsnyheter Rogaland (06.06.2025) Showing the finds from the cathedral in Stavanger.
Søndeland, G. (04.06.2025) Secret revealed: Stavanger's history must be rewritten, RA Stavanger.
Stenslad, K. (29.12.2024) The year of archaeology - incredibly exciting, Stavanger Aftenblad.
Knutsen, K. A. (11.06.2024) Researching the glue that holds the cathedral together, Stavanger Aftenblad.
THE STICKING STONES TEAM
Bettina Ebert is a conservator and associate professor in the conservation of cultural heritage at the Museum of Archaeology, UiS.
She specialises in medieval art and material culture, and undertakes interdisciplinary research that bridges scientific and humanistic approaches to cultural heritage. Currently working with built heritage and medieval material culture, Bettina also has expertise in the conservation of modern and contemporary art.
Bettina has always been interested in natural resins, adhesives and consolidants. This project combines her passion for historic material technology with her desire for contributing research that is relevant to conservation practice.
Silas Ploner studied restoration & conservation of stone at the Universities of Applied Sciences in Erfurt and Potsdam.
After graduating, he worked as a freelancer on various restoration projects before taking up a permanent position with the Bavarian Palace Administration in Munich. The last years, he was responsible for the planning, supervision and management of all restoration campaigns in the state-owned palaces, castles and historic sites.
Silas specialises in the theoretical and practical conservation of built heritage and has a passion for translating theory into practical concepts. He is pursuing his PhD in the Sticking Stones Project.
Kjartan Hauglid is an art historian and researcher at the Norwegian Institute for Cultural Heritage Research.
His main fields of interests are medieval art and architecture, building archaeology, iconography, and patronage. Hauglid has published several articles on medieval churches in Norway. He is an experienced photographer and has contributed to numerous publications as a photographer and copyeditor.
Torbjørg Bjelland is associate professor at the Museum of Archaeology, University of Stavanger. She is a botanist and lichenologist with expertise in stone deterioration.
Torbjørg has experience with a range of analytical methods and statistical data analysis, contributing with expertise in biological deterioration of cultural heritage in stone and data interpretation.
Paul Kozowyk's research is at the intersection of archaeology and materials science. He uses experimental archaeology to reconstruct lost ancient and traditional technologies. By identifying archaeological remains, recreating production processes, and testing the materials using modern adhesive testing standards, he provides new insight into the behaviour and technology of ancient humans.
Paul's current aim is to apply the experience he gained researching and testing ancient plant-derived adhesives towards a modern functional role. This involves reconstructing wood tars used as masonry adhesives during the Middle Ages and developing a modern equivalent to use in conservation efforts.
Wido Quist is Associate Professor in Heritage & Technology at the Faculty of Architecture and the Built Environment, TU Delft.
His research and teaching centres around the preservation and adaptive re-use of the built legacy of the 20th century, connecting the specialist disciplines.
Intertwining values, design and technology, he is an expert on the crossing between historical knowledge of building materials and strategies for conservation and re-use. He has specific expertise in natural stone and historic concrete.
Joy Mazurek specialises in the identification of natural and synthetic organic materials by gas chromatography/mass spectrometry.
She obtained her master's degree in biology and currently works at the Getty Conservation institute, Los Angeles.
Ingunn Thorseth is professor emeritus at the Department of Earth Sciences, University of Bergen.
She is a geologist with significant expertise in inorganic material identification. Her principal research interests are geochemistry and geomicrobiology.
ADVISORY PANEL
Dr. Michael Schilling, Getty Conservation Institute
Head of Materials Characterization research at the GCI, which focuses on development of analytical methods for studying classes of materials used by artists and conservators. He specializes in gas chromatography, mass spectrometry and thermal analysis applications.
Ann Meeks, stone conservation team, Museum of Archaeology, UiS
Stone conservator and stakeholder representative. She has worked on Stavanger cathedral since the late 1990s, and knows the cathedral and its conservation history in depth. She is an experienced stone conservator and has interest in methods of joining and repair.
Hege S. Eilertsen and Henrik Smit, Norwegian Directorate for Cultural Heritage
Cultural heritage management advisors
Ivan Piñerez Torrijos and Kari Birgitte Melvær Wiig, Validé, the technology transfer office of UiS
Innovation and intellectual property advisors
