When neutron scattering and rheology aid the restoration of works of art

Objectives

Works of art, particularly old paintings, suffer the ravages of time. Dust, soot, oxidation and free radical attack inevitably alter their appearance. After several decades, a formerly coloured painting can become uniformly brown, black or white, while its protective varnish becomes opaque, cracked and irregular.

To remedy this deterioration, paintings are regularly restored. These restorations, although essential, entail risks. Removing old varnishes and replacing them with fresh coats often involves the use of solvents, which, if left unchecked, can irreparably damage the paint. The 20th century is infamous for the large number of paintings damaged not by natural disasters, but by poorly executed restorations.

Results

The role of neutrons and rheology in restoration

The research work, carried out in collaboration with the Institut Laue-Langevin (ILL), explores the physico-chemical interactions that govern the penetration of solvents into the polymers used in art and the resulting morphologies. These studies combine neutron reflectometry, rheology and the analysis of phase diagrams of ternary systems to understand these complex phenomena. These advances have led to publications in Soft Matter and Langmuir.

More recently, glass ageing and its impact on the physical properties of artistic materials were the subject of an article published in 2024 in the Journal of Polymer Science. This research uses complementary techniques, such as calorimetry, rheology and refractometry, to analyse changes in the mechanical and visual properties of works of art over time. By combining these approaches, this work provides a solid basis for improving restoration methods and preserving artistic heritage over the long term.

Towards safer, automated catering  

The results of these studies pave the way for a review of current restoration practices. By combining advanced techniques such as neutron reflectometry and rheology, the researchers are proposing approaches to better control the interactions of solvents with varnish layers. These advances could lead to safer automated restoration techniques, although human intervention remains essential to supervise the process and guarantee the safety of the works.

This research demonstrates how the combination of neutrons, rheology and other physico-chemical tools can transform art restoration, offering scientific solutions for preserving our cultural heritage while respecting its integrity.

References

• Rharbi, Y., & Hugennel, F. (2024). Physical aging of a glassy polymer in cultural heritage conservation. Journal of Polymer Science, 62(5232). 
• Castel, A., Gutfreund, P., Cabane, B., & Rharbi, Y. (2020). Stability of fluid ultrathin polymer films in contact with solvent-loaded gels for cultural heritage. Langmuir, 36(42), 12607-12619. 
• Castel, A., Gutfreund, P., Cabane, B., & Rharbi, Y. (2020). Swelling, dewetting and breakup in thin polymer films for cultural heritage. Soft Matter, 16(6), 1485-1497. 

Media coverage

• The Telegraph (2020) : Museums warned cleaning products are irreversibly damaging great masterpieces

This article highlights the risks associated with the use of cleaning products in the restoration of works of art, a subject directly linked to our research into the impact of solvents and innovative preservation methods.

• Farbe und Lack (2020) : Schonender Ansatz zur Restaurierung wertvoller Gemälde

The article explores delicate and innovative restoration techniques, including the use of solvent gels studied as part of our research, to protect works while minimising the risk of damage.