An overall view of the painting and a detail showing the discoloured, degraded, and uneven layer of varnish.
Gunnar S. Gundersen, “Winter Sun”, 1966. © Gundersen, Gunnar S./BONO
Photo: Nasjonalmuseet / Børre Høstland

This PhD research project examines new cleaning methods for the removal of artist-applied commercial synthetic varnishes from sensitive modern paintings. Ten varnished acrylic paintings will be used as case studies to test the removability of varnishes. These paintings were made in the period of 1966–1982 by prominent Norwegian artists represented in the collection of the National Museum.  

Examining methods to safely remove degraded varnishes

Acrylic varnishes can become discoloured over time, getting cloudy and milky, and affecting the clarity of the colours and the composition of a painting. This can negate the impact and meaning of the artwork. The research will review a range of synthetic varnishes produced by several leading commercial paint manufacturers used by Norwegian artists. The project aims to find an appropriate and sustainable cleaning method to safely remove degraded acrylic varnishes without affecting the underlying acrylic and PVA (polyvinyl acetate) paint films. Removing these varnishes is challenging due to the chemical similarity of the paint and the varnish.  

A selection of commercially available varnishes from various manufacturers, designed for use over acrylic paint.
Photo: Laura Homer

Collaboration with a mobile laboratory

The project has received scientific support from the mobile laboratory MOLAB, which is financed by the EU-funded IPERION HS programme. Nine scientists visited the National Museum in the summer of 2023, and carried out non-invasive scientific analysis of the case-study paintings, using six different analytical instruments. The results of these analyses will be used to select materials for artificially aged mock-up test paintings, in order to test the removability of the varnishes in a safe way. New cleaning methods, such as the use of nanogels, nanostructured fluids, and PVA-Borax gels, will be tested and evaluated.  

An overall view of the painting and a detail showing the discoloured, degraded, and uneven layer of varnish.
Dag Skedsmo, “Untitled”, 1980. © Skedsmo, Dag/BONO
Photo: Laura Homer

Research institutions

The research is fully funded by the National Museum and is carried out in affiliation with the University of Oslo. The research will be presented at relevant international conferences, as well as through peer-reviewed articles and publications. A unique feature of this research is the ongoing, open dialogue with living artists about their choices of materials and use of varnishes.  

Project advisors

  • Professor Noëlle Streeton, University of Oslo
  • Senior conservation scientist Bronwyn Ormsby, Tate, London 
  • Professor Gunnar Heydenreich, Cologne Institute of Conservation Sciences 

Further reading 

  • The text “Laura Homer: Hvordan nanoteknologi kan redde ikoniske akrylmalerier” (2024) by Monica Høyer, about the use of nanotechnology in the conservation of paintings (article in Norwegian).
  • The chapter “Varnishing of acrylic paintings by artists” by Mark Golden in the book Conservation of Easel Paintings (2021), edited by Joyce Hill Stoner and Rebecca Rushfield, published by Routledge. 
  • The text “A preliminary evaluation of artists’ and conservation varnishes for acrylic emulsion paint films” (2011) by Bronwyn Ormsby et al., published as a postprint for the ICOM Committee for Conservation 16th Triennial Conference in Lisbon.