Raking light means a band of light running parallel to the surface, or in a very narrow angle to the surface. It is necessary that this band be condensed by lenses and be well defined in order to obtain a contrast between the illuminated areas and those remaining in shadow. In addition, it is important to avoid the diffusion of the light because it cancels the effect sought after. Under these light conditions, all the defects on the surface are accentuated to the point that the resulting image of the painting is almost unrecognisable. The raking light makes even the minute flaking of the pictorial film and the ground preparation visible. This information guides the restorer in the execution of localised interventions and in the verification of the results.