Optical Methods for the Assessment of Transport and Age Induced Defects of Artwork

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

“…The use of strain maps to show the potential areas of concern and highlight areas of potential degradation in the paintings have been optimized for ease of interpretation by conservators [111]. Shearography has also been paired with other imaging techniques such as terahertz imaging, fringe projections to observe 3D topographic maps, and reflectance transformation imaging to provide more complete datasets for diagnosing defects and changes in a painting after environmental fluctuations or transport [107,112,113]. Some optimization of strain maps from the displacement gradients was also performed on a test painting to quantify the strain experienced by a painting as a result of cycling lights in a museum setting [107,114].…”

The Noninvasive Analysis of Painted Surfaces: Scientific Impact and Conservation Practice

“…This optical phase sampling method assumes that during the capturing of the required four interferograms at each deformation state, the object and the surrounding environment are steady and do not induce a significant phase change on their own. The adequacy of this assumption has been verified through pilot tests in the museum environment based on the test setup described later in this chapter, as well as based on the literature (Kalms and Jueptner, 2005;Morawitz et al, 2013). This optical phase sampling method was chosen because of its superior spatial resolution, allowing for a quantification of the phase sampling at each pixel individually.…”

“…This optical phase sampling method was chosen because of its superior spatial resolution, allowing for a quantification of the phase sampling at each pixel individually. The specific choice of the number of phase shifts and phase step size was defined on the basis of pilot studies of shearographic measurements on oil-on-canvas paintings in our laboratory settings Khaleghi et al, 2014) as well as literature (Kalms and Jueptner, 2005;Morawitz et al, 2013). Further work might be needed to find an optimal phase sampling technique and corresponding acquisition parameters; however, the ones used in this work were deemed sufficient for our preliminary work.…”

“…As a highly sensitive technique for measuring gradients of displacement, shearography also has great potential for applications in art conservation (Groves et al, 2009a(Groves et al, , 2009bSfarra et al, 2011;Meybodi et al, 2012;Morawitz et al, 2013). In recent years, the majority of shearography-based research into art conservation applications has taken place in Europe, with the Institute for Technical Optics at Stuttgart University and the Foundation for Research and Technology-Hellas (FORTH) in Crete, Greece, each being research hotbeds.…”

“…In recent years, the majority of shearography-based research into art conservation applications has taken place in Europe, with the Institute for Technical Optics at Stuttgart University and the Foundation for Research and Technology-Hellas (FORTH) in Crete, Greece, each being research hotbeds. Most of the research has focused on detecting delamination or structural flaws in panel or wall paintings (Kalms and Jueptner, 2005;Morawitz et al, 2013). Tornari and her group at the Institute of Electronic Structure and Laser-FORTH spearheaded the development of a hybrid portable interferometry-shearography system entitled "MultiEncode: Multifunctional Encoding System for Assessment of Movable Cultural Heritage," in which a shearography-based system was developed to monitor the condition of paintings before and after transport (Groves et al, 2007;Tornari et al, 2009).…”