Munch and optical coherence tomography: unravelling historical and artist applied varnish layers in painting collections
The National Museum of Art, P.O. Box 7014, St. Olavs Plass, 0130, Oslo, Norway
2 Department of Archaeology, Conservation and History (IAKH), Conservation Studies, University of Oslo (UiO), Postboks 1008 Blindern, 0315, Oslo, Norway
3 Department for Conservation and Restoration of Paintings and Polychromed Sculpture, Faculty of Fine Arts, Nicolaus Copernicus University, ul. Gagarina 7, 87-100, Toruń, Poland
4 Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, Post Box 1033, Blindern, 0315, Oslo, Norway
5 Institute of Physics, Nicolaus Copernicus University. Ul, Grudziadzka 5, 87-100, Toruń, Poland
6 Programme Conservation and Restoration of Cultural Heritage, University of Amsterdam (UvA), Johannes Vermeerplein 1, 1071 DV, Amsterdam, Netherlands
Accepted: 14 July 2021
Published online: 1 September 2021
Effective care of large-scale museum collections requires planning that includes the conservation treatment of specific groups of art works, such as appropriate cleaning strategies. Optical coherence tomography (OCT) has been successfully applied as a non-invasive method for the stratigraphic visualisation of the uppermost transparent and semi-transparent layers in paintings, such as varnishes. Several OCT case study examples have further demonstrated the capabilities of the non-contact interferometric technique to measure the thickness of the various varnish layers, to help monitor cleaning and associated optical changes, and to detect past restorations. OCT was applied for the detection of varnishes to 13 paintings by Edvard Munch (1863–1944) owned by the Norwegian National Museum of Art. The paintings have a controversial and complex varnish history and are displayed as a group according to their acquisition legacy. A prototype high-resolution portable SdOCT instrument was used in combination with complementary imaging techniques. Questions concerning thickness, stratigraphy and the identification/location of the artist’s original varnish layers and/or pigmented glazes were addressed. Findings confirmed the complexity of the historical layers present and provided new evidence for Munch’s use of transparent and semi-transparent layers as part of an occasional, localised varnishing and/or glazing technique.
© The Author(s) 2021
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