NMR relaxometry of oil paint binders

Abstract

Mobile nuclear magnetic resonance (NMR) is a flexible technique for nondestructive characterization of water in plants, the physical properties of polymers, moisture in porous walls, or the binder in paintings by relaxation measurements. NMR relaxation data report material properties and therefore can also help to characterize the state of tangible cultural heritage. In this work, we discuss the relaxation behavior in two series of naturally aged paint mock‐up samples. First, paints with different pigment concentrations were prepared and investigated in terms of the longitudinal and transverse relaxation‐time distributions. We document the evolution of both relaxation‐time distributions during the initial drying stage and demonstrate the heightened importance of transverse over longitudinal relaxation measurements. Second, we observe nonlinear dependences of the relaxation times on the pigment concentration in a typical oil binder. Third, in a study of naturally aged paint samples prepared in the years between 1914 and 1951 and subsequently aged under controlled conditions, we explore the possibility of determining the age of paintings using partial least square regression (PLS) by fitting T1–T2 data with the sample age. Our results suggest some correlation, albeit with significant scatter. Estimating the age of a painting stored under unknown conditions from NMR relaxation data is therefore not feasible, as the cumulative effects of light irradiation, humidity, and biological degradation further obfuscate the chemical and physical impact of aging on the relaxation times in addition to the impact of pigment concentration.

“1984”: What Orwell could not predict. Proteomic analysis of his scripts

“…Busse et al. [21] devised an NMR relaxometry method for monitoring oil paint binders. They observed nonlinear dependences of the relaxation times on the pigment concentration in a typical oil binder.…”

Connecting Rheological Properties and Molecular Dynamics of Egg‐Tempera Paints based on Egg Yolk

“…At this frequency, the relaxation rate R 1 of the dispersion of green earth, which contains paramagnetic species, increases with the pigment concentration (Figure 3). The presence of a paramagnetic center is indeed supposed to increase the relaxation and thus R 1 [19] . Conversely R 1 seems approximately constant for the tempera paint meaning that these protons are not directly in interaction with the mineral surface we can thus assign them to the lipoproteins of the yolk.…”

After the paint has dried: a review of testing techniques for studying the mechanical properties of artists’ paint

“…Model systems of traditional oil paints, water-miscible oil paints, and acrylic paints with varying PVC values were studied to determine if the comparative results could be quantified as a function of increasing PVC [14,[129][130][131][132]. One of these studies looked to extend their findings with young model systems to see if they could develop a protocol for determining the age of paint materials based on the response of the relaxations times, which was unfortunately inconclusive [131]. Single-sided NMR has also been used to study the effects of solvent exposure on the stiffness of paints.…”