Radiography
The radiography of artworks is based on the same principles as the radiography of the human body. When a work is examined under X-rays produced by specific sources, it is possible to detect the different behavior of materials (absorption or passage of radiation) and record it in a black and white x-ray film (plate). Due to their penetrating power, X-rays are able to penetrate the entire mass of the work, whether it is painting or a sculpture. The different amount of radiation absorbed by the various layers is determined by many factors, such as the nature of the materials with which they are made, their thickness, the radiation energy, etc. This method gives a variety of information about the internal structure of the project, e.g. whether there's been damage by wood eating insects, the existence of internal metal components, etc., or even the existence of over-paintings or losses on the surface.