Restoration of a Painting

During the Romantic period of the 19th century, Europeans were fascinated by non-Western cultures. Paintings of these subjects, often fantasized, became popular. The painter Wilhelm Gentz, however, relied on first-hand experience in the harem of Cairo for this painting of Ottoman life.

When the conservation of this painting began, it became apparent there had been very little prior restoration, except that the canvas had been relined (backed with another canvas for support). Time, variations in temperature, and humidity affected both the surface and the structure of the painting and its frame.

We start by looking at these two women, leading the procession. As we can see, the painting had dusty, yellowed varnish. Though the surface had cracked significantly, as is usual for canvases of this age, very few losses of paint had occurred.


To get a better look at the painting, several techniques were used to reveal the artist’s secrets.

Raking light, or light coming from a source shining parallel to the picture plane, is often used to closely examine paintings. It reveals the differing textures of painted areas, with the peaks shown in bright light with cast shadows in lower areas.


In this close up, the raking light reveals a thick edge around the figure’s head, indicating that the artist used a palette knife to remove his first version and replaced it with the current version.

X-radiography reveals density, useful for determining thickness and composition of painting layers. The underlying structure of the painting can reveal much about technique, aging, and previous restoration or conservation.


Here, the x-ray reveals stress cracking of the thickly painted figures, not visible in the thinner-painted background.

In this detail of the conserved state of the painting, the yellowed varnish has been removed and the textures restored to the brushwork.

The unconserved state of the figure of the guard is murky, the yellowed varnish blurring the distinctions between cloth, shadow, and the guard’s dark skin.

Examination under infrared light, a type of light invisible to the human eye, can be used to create an image of layers below the surface of the painting.


Often used to reconstruct underdrawing, which tends to reflect infrared light, it can also give information about changes to the paint layer caused by damage or repainting.


The infrared camera images seen here reveal the drawing below the painted surface of the guard’s head—the crisp outlines are preserved in the finished painting with few alterations.

Comparing the figures to the scenery of the painting shows a marked difference in technique and reveals the artist’s true interest.

The background differs from the figures of the guard and two women in that no underdrawing is visible under the foliage, indicating the artist’s sure method in creating the garden.

Discoveries involving the artist’s working method can inform the conservation process itself: Differing thicknesses of paint, for example, require different techniques to achieve structural stability. When shared among scientists, this information can affect the conservation of other works of art by the same artist or even others of the same period, as it can point toward potential issues in other paintings.

In addition to returning objects as close to their original state as possible, the science of conservation has also revolutionized the field of art history and curatorial practice. Modern examination methods allow us to look below the surface of paintings to reveal underdrawings, information about the artist’s working process, and other information that confirms or denies authenticity.