Netherlands Institute for Conservation, Art and Science

The cleaning of paintings

A molecular perspective

The focus of this project is degradation phenomena related to the cleaning of paintings. In order to be exposed to the public in pristine condition, paintings in collections all over the world are repeatedly exposed to organic solvents for the removal of varnishes and to aqueous solutions for surface cleaning.

In addition, keeping the relative humidity constant and relatively low in both museum conditions and during storage of paintings is accepted to be a good strategy for limiting degradation phenomena in paints.

Although also based on scientific research, these measures and methodologies are often based on practical experience and risk limitation. On a molecular level, reactions inside aging oil paints are not yet well-understood.

Questions that are dealt with in this project include for example: can the exposure of a paint surface to solvents trigger new reactions inside the paint? How do reactions inside paint layers, such as metal soap crystallization, depend on varying conditions? What is the role of water on a molecular level?

Due to the inherent multidisciplinary nature of these questions, the use of various analytical techniques is required.  This project therefore combines many sub-disciplines of chemistry such as inorganic-, organic-, polymer-, analytical chemistry and spectroscopy.


The synthesis of a zinc carboxylate complex for the study of zinc oxide related degradation in oil paints.

Principal researcher

Lambert Baij (University of Amsterdam, Rijksmuseum)

Type of project


Participating researchers

  • Piet Iedema (supervisor)
  • Katrien Keune (supervisor)
  • Joen Hermans

Institutions involved

  • University of Amsterdam
  • Rijksmuseum


Expected completion date

March 2020.

Carried out within the framework of the NANORESTART project (EUHorizon 2020 agreement No 646063).

Published by  NICAS

14 November 2017