The "PICUS" system in the detection of defects on panel paintings and wooden boards

The technique of panel painting played a particularly significant role in Italian art, especially between the thirteenth and sixteenth centuries, before canvas came into general use. The conservation of panel paintings, however, is complex and largely depends on the original materials and techniques used to create the support and the many layers of preparation for painting. The state of conservation is influenced also by the history of stress/deformation that the painting has undergone and the microclimatic conditions in which it is exposed. The large thermo-hygrometric variation induces changes in the structure of the wood and can create cracks even for the gypsum which is more rigid than the wood and can develop dangerous detachments. Recently, a low-cost, portable test system for the measurement of detachments between layers of architectural coatings, called PICUS, inspired by the method used by restorers during diagnosis and conservation interventions, has been successfully developed. The same system was then tested to acquire information about the execution technique, the state of conservation and previous interventions of stratified structures such as paintings on wood.