Non-invasive characterisation of varnished modern paintings: comparative insights and conservation implications

Year: 2026

Authors: Homer L., Targowski P., Kowalska M., Iwanicka M., Rosi F., Cartechini L., Buti D., Liang HD., Cheung CS., Liggins F., Atkinson P., Fontana R., Vannini E., Lunghi I., Karagiannis G., Karagiannis T., Bartoletti A., Ormsby B.

Autors Affiliation: Natl Museum Art Architecture & Design, POB 7014, N-7014 Oslo, Oslo, Norway; Nicolaus Copernicus Univ Torun, Inst Phys, Ul Grudziadzka 5, PL-87100 Torun, Poland; Nicolaus Copernicus Univ Torun, Fac Fine Arts, Ul Sienkiewicza 30-32, PL-87100 Torun, Poland; Inst Chem Sci & Technol SCITEC CNR, Via Elce di Sotto 8, I-06123 Perugia, Italy; CNR, Inst Heritage Sci ISPC, Area Ric Firenze, Via Madonna del Piano 10, I-50019 Florence, Italy; Nottingham Trent Univ, Sch Sci & Technol, ISAAC Lab, Nottingham NG11 8NS, England; CNR, INO Natl Inst Opt, Largo Enrico Fermi 6, I-50125 Florence, Italy; Univ Florence, Dept Phys & Astron, Via G Sansone 1, I-50019 Florence, Italy; Univ Florence, Dept Chem Ugo Schiff, Via Lastruccia 3-13, I-50019 Sesto Fiorentino, FI, Italy; ORMYLIA Fdn Art Diag Ctr, GR-63071 Ormylia, Chalkidiki, Greece; Diag Multisyst, GR-63200 Nea Moudania, Chalkidiki, Greece; Tate Britain, Conservat Dept, Millbank, London SW1P 4RG, England.

Abstract: This study presents the results of a non-invasive analytical investigation into eight varnished modern paintings from the Norwegian National Museum, dating from 1966 to 1982. These works, executed in either waterborne acrylic dispersion resin or polyvinyl acetate (PVAc) media, have not been examined before. They form part of a broader research initiative aimed at documenting the use and degradation of synthetic, waterborne varnishes over acrylic and vinyl paints in the context of Norwegian modern art, and the implications for conservation treatments. The eight paintings were examined through the mobile laboratory (MOLAB) platform of the European infrastructure for Heritage Science (E-RIHS). Multiple complementary techniques, including optical coherence tomography (OCT), external reflection infrared spectroscopy (ERIRS), x-ray fluorescence (XRF) mapping and optical micro-profilometry, were employed to identify binders and pigments, assess varnish thickness and distribution and document the layer structure without sampling. The results of a central case study, Winter Sun , 1966, by Gunnar S. Gundersen (1921-1983) (MS-02579-2988, acrylic on canvas, 165 x110 cm), are presented including characterisation of the layer structure, and identification of the paint and varnish compositions. Comparative analysis between the case study paintings highlights both prevalences and differences within the materials used, informing material history and artistic practices within the mid-century Norwegian context. This in turn informs conservation approaches to the as-yet unresolved challenge of varnish removal from waterborne modern paints. The findings have the potential to inform the future design of representative mock-ups to test potential varnish removal systems. This multimodal, non-invasive approach offers new tools for understanding artist materials and supports conservation decision-making by clarifying when and how varnish removal may be appropriate. (c) 2025 The Author(s). Published by Elsevier Masson SAS. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Journal/Review: JOURNAL OF CULTURAL HERITAGE

Volume: 77      Pages from: 127  to: 139

More Information: The mobile, non-invasive analytical research was supported by IPERION HS-Integrating Platforms for the European Research Infrastructure ON Heritage Science Project Horizon 2020 Programme of the EU (Grant Agreement n.871034). The contents reflect only the authors’ view, and the European Commission is not responsible for any use that may be made of the information it contains. The PhD research project is funded by The National Museum of Norway.
KeyWords: Acrylic dispersion resin; Vinyl resin; Waterborne varnish; Norwegian modern art; MOLAB
DOI: 10.1016/j.culher.2025.11.007