Raking light, the illumination of objects from a

light source Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terah ...

at an oblique angle or almost parallel to the surface, provides information on the surface topography and relief of the artefact thus lit. It is widely used in the examination of works of art.

Examination of paintings

Using raking light, the effects of

impasto ''Impasto'' is a technique used in painting, where paint is laid on an area of the surface thickly, usually thick enough that the brush or painting-knife strokes are visible. Paint can also be mixed right on the canvas. When dry, impasto provides ...

and the surface texture of a

painting Painting is the practice of applying paint, pigment, color or other medium to a solid surface (called the "matrix" or "support"). The medium is commonly applied to the base with a brush, but other implements, such as knives, sponges, and ai ...

are accentuated by the increased illumination of surfaces facing the light source and the exaggeration of shadows on surfaces facing away from the light source. In some instances raking light may help reveal

pentimenti A pentimento (plural pentimenti), in painting, is "the presence or emergence of earlier images, forms, or strokes that have been changed and painted over". The word is , from the verb , meaning 'to repent'. Significance Pentimenti may show that ...

(changes in an artist's intention). In the case of wall paintings, raking light helps show preparatory techniques such as incisions in the plaster support.

Conservation

Conservators In certain areas of England, Conservators are statutory bodies which manage areas of countryside for the use of the public. Establishment, Role and Powers Conservators are bodies corporate generally established, and granted their powers, by a ...

examine objects under raking light during

visual inspection Visual inspection is a common method of quality control, data acquisition, and data analysis. Visual Inspection, used in maintenance of facilities, mean inspection of equipment and structures using either or all of raw human senses such as vision ...

and for condition recording. In the examination of easel paintings, raking light may help document

craquelure Craquelure (french: craquelé; it, crettatura) is a fine pattern of dense cracking formed on the surface of materials. It can be a result of drying, aging, intentional patterning, or a combination of all three. The term is most often used to ref ...

, paint cupping, uneven tension in a

canvas Canvas is an extremely durable plain-woven fabric used for making sails, tents, marquees, backpacks, shelters, as a support for oil painting and for other items for which sturdiness is required, as well as in such fashion objects as handb ...

, or

warp Warp, warped or warping may refer to: Arts and entertainment Books and comics * WaRP Graphics, an alternative comics publisher * ''Warp'' (First Comics), comic book series published by First Comics based on the play ''Warp!'' * Warp (comics), a ...

in a

panel Panel may refer to: Arts and media Visual arts *Panel (comics), a single image in a comic book, comic strip or cartoon; also, a comic strip containing one such image * Panel painting, in art, either one element of a multi-element piece of art ...

. In the examination of wall paintings, raking light can help document surface deterioration phenomena such as the

efflorescence In chemistry, efflorescence (which means "to flower out" in French) is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water, or ...

salts In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively ...

and micro-

delamination Delamination is a mode of failure where a material fractures into layers. A variety of materials including laminate composites and concrete can fail by delamination. Processing can create layers in materials such as steel formed by rolling an ...

, and may be used for monitoring the effects of conservation interventions.

References

{{Reflist Imaging 3D imaging Painting Conservation and restoration of cultural heritage

Examination of paintings

Conservation

See also

References