X-rays were first discovered in 1895 by a physicist x-ray, who a few years later in Munich and made the first x-ray picture. In France, such experiments were carried out only during the First world war, in 1915, by Dr. Ledoux-Lebard and his assistant Gulin. The work was continued at the Louvre in 1919 by Dr. Sharon. Systematic research began in museums only a few years later: in the Louvre - in 1924 (Celery and Gulina), later in the art Museum Fogg (Burroughs), in England (Christian Walters) and Portugal (Santos). After world war II, radiography became the most commonly used method of analysis. The laboratories use weak x-rays. Generators - most often anti-cathode tungsten lamps, similar to those used in medicine. There are also devices for very low radiation lamps with beryllium window and water cooling. X-ray films are placed in an envelope of black paper and can come into contact with the picture without risk. The clarity of the resulting image depends in part on the degree of contact of the film with the surface of the picture. X-rays recreate the invisible appearance of the picture. However, if the basis of the picture is thick, and the soil of high density, the internal structure of the picture may be poorly understood, but if the radiation passes through the canvas and the soil easily, the paints used for the preparatory drawing are usually based, easily identified and thus revives the invisible state of the picture, the stage of creativity, previously inaccessible to perception. The x-ray does not always show the first stage of work. For example, in the picture of E. Lesuer "Muse" revealed a complex combination of the first and second stages of the work face can be seen simultaneously in profile and in FAS. If, on the contrary, the picture was painted with paints of low intensity, and then covered with wide glazes, we will not see this first stage. The painting is subjected to x-ray analysis in order to draw a conclusion about the state of the painting on the eve of restoration or for the purposes of interest to art historians. But the most accurate results from radiography can be expected in determining the composition and condition of the base. Basis. The basis is called a wooden or copper Board or canvas, which is applied to the paint layer. When you need to examine a picture written on copper, which, however, is rare, radiography can not help, since the weak x-rays used in the analysis are not able to pass through the metal. However, if you use the rays of greater penetrating power, they will not give any information about the most colorful layer. In this case, some clarity can make only the study of the pattern in infrared and ultraviolet rays. When we are talking about the picture, painted on wood (and there are paintings up to the XVII century were the majority), only it may be useful to study the properties and structure of wooden framework, visual examination which is often difficult. The wooden base is hidden on one side with a colorful layer, and the other side of the artist himself sometimes covers the ground to avoid moisture. This soil is usually monochrome or decorated with marble. When the colorful layers and soil are permeable x-rays, you can get a radiograph of the wooden base. Often the initial basis of the studied picture has damages (wood parasites, looseness of boards) and needs strengthening, support ("parquet"), formed by vertical and horizontal crossbars, superimposed on the basis. Thus, it is quite difficult to study the initial basis, as it is visible only a few millimeters from the edge. With the help of x-rays, it is possible to establish the structure of the original wooden base and the wood species, which varies depending on the geographical origin of the picture; based on this information, you can get accurate information about the work. When the picture is painted on a thick wooden base of soft wood, the base is often struck by wood parasites, which make it whole moves; they can be identified on the x-ray. It is necessary to know the true state of the Foundation. Radiography allows you to trace the result of actions taken with the picture, and to find the technical means and techniques used by primitive artists. So, on the x-ray you can see the pieces of rough canvas included in the ground to the joints of the boards did not appear on the most colorful layer. A fiber-raw, mixed with lime mortar, used in many paintings of the XIV century In the XVII and XVIII centuries, paintings generally were painted on canvas, which is then duplicated, that is further strengthened by another canvas; this canvas (usually late XVIII or XIX century) does not allow to see the original basis. Dubbed canvas, provided that the primer he was not imbued with whitewash, does not submit to x-ray much of a problem. Characteristics of the canvas depend on the country and the era where and when the work was created. Thus, Venetian paintings often have a woven pattern; Rembrandt used simple canvases. Thanks to x-ray images can determine all the features of the tissues. X-rays detect not only the type of canvas, but also inserts into them. X-ray allows you to assess the degree of change (inserted or cropped picture). According to the materials of the encyclopedia of art ArtWiki