Micro-Mapping of Defect Structural Micro-Morphology in the Documentation of Fresco Wallpaintings

Abstract

This study proves the defect micro-morphology as a crucial parameter in conservation approaches. The study was performed on mural paintings and fresco samples which are considered as a major piece of European Cultural Heritage (CH). Nowadays the atmospheric pollution and various other extreme events provoke, more often than in the past, abrupt changes of environmental conditions, affecting negatively the murals state. Random contraction and expansion of the painting's complex structure is an important cause of extra load in its mechanical condition. This may eventually lead to the propagation of cracks within the layers, and expansion of the detachments. Furthermore, the sudden changes in the heterogeneous materials of the support can potentially trigger further damage to the multilayered painted surface. These subsurface damages may lead to unpredictable evolution of detachments and cracks, crucially affecting the painted surface. It is well known that a variety of techniques are employed to detect the location and the dimensions of the various detachments, hidden under the surface. In the present study emphasis is given on the importance of the detection and exact knowledge of the structural micro-morphology as a key factor to monitor the hidden, but ongoing, detachment processes. The precise monitoring of the detachments' micro-deformation will enhance the knowledge of the defect structure and help to visualize the interactions undergoing with the rest of the structure and thus will facilitate the choice of materials that will be used in the consolidation interventions, as well as their application guidelines. Hence, high resolution is of prior importance in monitoring the detection processes and as such laser metrology is implemented in this study.