Abstract In this study, portable NMR was applied to monitor and evaluate cleaning treatments on the surface of a 16th century Italian wall painting. Due to the complexity of the state of degradation of the wall painting, a campaign of measurements was carried in situ to evaluate the performance of traditional and innovative eco-friendly cleaning systems such as sulphate-reducing bacteria D. vulgaris confined in hydrogels, and to compare two different cleaning systems used to remove a degraded hydrophobic organic layer. Specifically, NMR stratigraphy allowed to determine the thickness of the organic layer covering the surface of the wall painting, its distribution in the wall painting, the presence of residues after applying the cleaning treatment, and to evaluate and compare the effectiveness of applied treatments. A new analytical parameter here named the solubilization degree of the cleaning system permitted the selection of the most performing treatment. 1H NMR depth profiles allowed to evaluate changes in the permeability of the wall painting caused by the presence of organic substances during the application of water-based cleaning systems, and to evaluate the water content and its depth of penetration in the wall painting. Changes in permeability were estimated calculating another new analytical parameter, i.e. the percentage of water saturation before and after the application of the cleaning treatment. Depth profiles also permitted the evaluation of the degree of wettability of the wall painting surface as a function of the time of application, and the obtainment of a detailed information about the interaction between water molecules, the gel network and the surface of the wall painting. Finally, to obtain the chemical characterization of the artefact surface a multi analytical approach was applied using both portable and micro-invasive analytical methodologies.

中文翻译：

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1 H NMR 深度剖面与便携式和显微分析技术相结合，用于评估清洁方法并识别 16 世纪意大利壁画的原始、非原始和降解材料

摘要 在这项研究中，便携式核磁共振被应用于监测和评估 16 世纪意大利壁画表面的清洁处理。由于壁画降解状态的复杂性，在原位进行了一系列测量，以评估传统和创新的环保清洁系统的性能，例如限制在水凝胶中的硫酸盐还原细菌 D. vulgaris，以及比较用于去除降解的疏水有机层的两种不同的清洁系统。具体而言，核磁共振地层学可以确定覆盖墙画表面的有机层的厚度、其在墙画中的分布、应用清洁处理后残留物的存在，并评估和比较应用处理的有效性。此处称为清洁系统溶解度的新分析参数允许选择性能最佳的处理。1H NMR 深度剖面允许评估在应用水性清洁系统期间由有机物质的存在引起的墙漆渗透性变化，并评估水含量及其在墙漆中的渗透深度。渗透率的变化是通过计算另一个新的分析参数来估计的，即在应用清洁处理之前和之后的水饱和百分比。深度剖面还允许评估墙漆表面的润湿程度作为应用时间的函数，并获得有关水分子之间相互作用的详细信息，凝胶网络和壁画表面。最后，为了获得人工制品表面的化学特征，使用便携式和微创分析方法应用了多分析方法。