Raking light, the illumination of objects from a light source at an oblique angle or almost parallel to the surface, provides information on the surface topography and relief of the artefact thus lit.
[1] In some instances, raking light may help reveal pentimenti (changes in an artist's intention).
[2] In the case of wall paintings, raking light helps show preparatory techniques such as incisions in the plaster support.
[3] Conservators examine objects under raking light during a visual inspection and for condition recording.
[4] In the examination of wall paintings, raking light can help document surface deterioration phenomena such as the efflorescence of salts and micro-delamination, and may be used for monitoring the effects of conservation interventions.