Using X-ray images
X-ray images are often used for the conservation and restoration of paintings. X-rays can reveal damage that is not visible to the naked eye such as damage that happened in the past to paint layers and their supports (canvases or panels).
X-ray images can tell us more about the artist’s working methods and the restoration history of a painting. It can also give us clues about the dating and authenticity of particular paintings and reveal any underlying images. It is a known fact, for example, that Van Gogh regularly painted over his previous works.
Anatomy of a canvas
X-ray images are essential for analysing the specific anatomical properties of canvases. Many nineteenth-century paintings were mounted on a supporting canvas (doubling). This hides the original back of the painting from view, so that the individual attributes of the original canvas, such as the fabric density, cannot be determined with the naked eye.
Many paintings from the nineteenth century and the early twentieth century were prepared with a layer of primer. This layer usually consists of components that can be clearly photographed using X-rays because of their basic composition, such as lead or zinc compounds. The contrast between the thicker and thinner parts of the primer reveals the specific canvas structure.