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 non-linear 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.

中文翻译：

---

油漆粘合剂的核磁共振弛豫

移动核磁共振 (NMR) 是一种灵活的技术，可通过弛豫测量对植物中的水分、聚合物的物理特性、多孔壁中的水分或绘画中的粘合剂进行无损表征。核磁共振弛豫数据报告材料特性，因此也有助于表征有形文化遗产的状态。在这项工作中，我们讨论了两个系列自然老化油漆模型样品的松弛行为。首先，制备了具有不同颜料浓度的涂料，并研究了纵向和横向弛豫时间分布。我们记录了初始干燥阶段两种弛豫时间分布的演变，并证明了横向和纵向弛豫测量的重要性。第二，我们观察到松弛时间对典型油性粘合剂中颜料浓度的非线性依赖性。第三，在对 1914 年至 1951 年间制备并随后在受控条件下老化的自然老化油漆样品的研究中，我们探索了使用偏最小二乘回归 (PLS) 通过拟合 T1 -T2 数据与样本年龄。我们的结果表明存在一些相关性，尽管具有显着的分散性。因此，根据 NMR 弛豫数据估计在未知条件下存储的绘画的年龄是不可行的，因为光照射、湿度和生物降解的累积效应进一步模糊了老化对弛豫时间的化学和物理影响，以及影响色素浓度。