Baij Lambert, Buijs Jesse, Hermans Joen J, Raven Laura, Iedema Piet D, Keune Katrien, Sprakel Joris
University of Amsterdam, Van 't Hoff Institute for Molecular Sciences, PO box 94720, 1090GD, Amsterdam, The Netherlands.
Rijksmuseum, Conservation and Science, PO box 74888, 1070DN, Amsterdam, The Netherlands.
Sci Rep. 2020 Jun 29;10(1):10574. doi: 10.1038/s41598-020-67115-1.
The exposure of oil paintings to organic solvents for varnish removal or to water for the removal of surface dirt can affect the chemical and physical properties of oil paint in an undesired way. Solvents can temporarily plasticise and swell the polymerised oil paint binding medium, enhancing both the thermal mobility and mechanical displacement of pigments embedded in this film. The enhancement of these microscopic motions can affect both the chemical and physical stability of the object as a whole. In order to minimise solvent exposure during cleaning, an analytical method that can quantitatively measure the microscopic motions induced by solvent uptake, is required first. In this study, we use Fourier Transform Laser Speckle Imaging (FT-LSI) and a newly developed portable FT-LSI setup as highly resolved motion detection instruments. We employ FT-LSI to probe pigment motion, with high spatiotemporal resolution, as a proxy for the destabilising effects of cleaning solvents. In this way, we can study solvent diffusion and evaporation rates and the total solvent retention time. In addition, qualitative spatial information on the spreading and homogeneity of the applied solvent is obtained. We study mobility in paint films caused by air humidity, spreading of solvents as a result of several cleaning methods and the protective capabilities of varnish. Our results show that FT-LSI is a powerful technique for the study of solvent penetration during oil paint cleaning and has a high potential for future use in the conservation studio.
油画接触用于去除清漆的有机溶剂或用于去除表面污垢的水，可能会以不良方式影响油画的化学和物理性质。溶剂可使聚合的油画粘结介质暂时增塑并膨胀，增强嵌入该漆膜中的颜料的热迁移率和机械位移。这些微观运动的增强会影响整个物体的化学和物理稳定性。为了在清洁过程中尽量减少溶剂暴露，首先需要一种能够定量测量溶剂吸收引起的微观运动的分析方法。在本研究中，我们使用傅里叶变换激光散斑成像（FT-LSI）和新开发的便携式FT-LSI装置作为高分辨率运动检测仪器。我们采用FT-LSI以高时空分辨率探测颜料运动，作为清洁溶剂去稳定化作用的替代指标。通过这种方式，我们可以研究溶剂扩散和蒸发速率以及总溶剂保留时间。此外，还可获得关于所施加溶剂的扩散和均匀性的定性空间信息。我们研究了由空气湿度引起的漆膜中的迁移率、几种清洁方法导致的溶剂扩散以及清漆的保护能力。我们的结果表明，FT-LSI是研究油画清洁过程中溶剂渗透的有力技术，在未来的保护工作室中有很高的应用潜力。
