The stability of paintings and the molecular structure of the oil paint polymeric network

Francesca Nardelli,Ilaria Bonaduce,Marco Geppi,Francesca Martini,Jacopo La Nasa,Celia Duce,Bronwyn Ormsby,Anna Lluvears-Tenorio,Judith Lee

doi:10.1038/s41598-021-93268-8

Francesca Nardelli, Ilaria Bonaduce + Show 7 more

Open Access

https://doi.org/10.1038/s41598-021-93268-8

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Abstract

A molecular-level understanding of the structure of the polymeric network formed upon the curing of air-drying artists’ oil paints still represents a challenge. In this study we used a set of analytical methodologies classically employed for the characterisation of a paint film—based on infrared spectroscopy and mass spectrometry—in combination with solid state NMR (SSNMR), to characterise model paint layers which present different behaviours towards surface cleaning with water, a commonly applied procedure in art conservation. The study demonstrates, with the fundamental contribution of SSNMR, a relationship between the painting stability and the chemical structure of the polymeric network. In particular, it is demonstrated for the first time that a low degree of cross-linking in combination with a high degree of oxidation of the polymeric network render the oil paint layer sensitive to water.

Highlights

A molecular-level understanding of the structure of the polymeric network formed upon the curing of air-drying artists’ oil paints still represents a challenge
Free fatty and dicarboxylic acids can be determined qualitatively and quantitatively by GC-MS based techniques[11,13,31,32], HPLC-MS14 and flow injection analysis coupled with ESI-MS33
HPLC-MS based methods are the methods of choice for glyceride profiling in p aintings[29], and flow injection analysis coupled with ESI–MS can help visualise the distribution of glycerides and more abundant oligomers in a paint layer[33,42]

Summary

Introduction

A molecular-level understanding of the structure of the polymeric network formed upon the curing of air-drying artists’ oil paints still represents a challenge. The study demonstrates, with the fundamental contribution of SSNMR, a relationship between the painting stability and the chemical structure of the polymeric network. It is demonstrated for the first time that a low degree of cross-linking in combination with a high degree of oxidation of the polymeric network render the oil paint layer sensitive to water. Free fatty and dicarboxylic acids can be determined qualitatively and quantitatively by GC-MS based techniques[11,13,31,32], HPLC-MS14 and flow injection analysis coupled with ESI-MS33. Analytical pyrolysis is the Scientific Reports | (2021) 11:14202

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